CN113579229B

CN113579229B - Nano metal 3D printing ink and application thereof

Info

Publication number: CN113579229B
Application number: CN202110680045.8A
Authority: CN
Inventors: 周南嘉; 陈小朋
Original assignee: Xihu Future Intelligent Manufacturing Hangzhou Technology Development Co ltd
Current assignee: Xihu Future Intelligent Manufacturing Hangzhou Technology Development Co ltd
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2023-04-18
Anticipated expiration: 2041-06-18
Also published as: TW202302774A; TWI823429B; WO2022262801A1; CN113579229A

Abstract

The invention provides nano metal 3D printing ink and application thereof. According to the invention, through the synergistic effect of the double reducing agents, a strong reducing agent such as hydrazine hydrate is used for quickly forming metal nanoparticles, and a weak reducing agent such as diethanolamine is used for slowly reducing and agglomerating metal particles on the surfaces of small-particle metal nanoparticles, so that the controllable synthesis of the metal nanoparticles is realized, and the effects of controllable size and monodispersity are achieved. The nano metal particles prepared by the method can be uniformly dispersed in the solution, and the slurry can be used for a high-precision direct-writing 3D printing process with the particle size of less than 10 mu m.

Description

Nano metal 3D printing ink and application thereof

Technical Field

The invention relates to the field of conductive ink manufacturing, in particular to nano metal 3D printing ink and application thereof.

Background

In recent years, with the gradual maturity of the metal 3D printing process, compared with the conventional process, the metal 3D printing process has incomparable advantages in aspects of shortening new product development and implementation periods, efficiently forming more complex structures, implementing integration, lightweight design, implementing excellent mechanical properties, and the like. With the expansion of the industrial scale of metal 3D printing, the problems of few kinds of metal powder materials, low quality, insufficient supply and the like in the market are becoming more and more obvious. For example, the most common commercial silver paste in the market generally adopts micron-level silver sheets, and when a screen printing process is adopted, the line width and the line distance reach 60-70 μm, but the line width and the line distance still reach 30-40 μm by adopting a laser engraving technology. Due to the problems of large particle size, easy agglomeration, difficult dispersion and the like of commercial silver paste, the high-precision direct-writing 3D printing process below 10 mu m cannot be met at present.

Therefore, the application range of the precision direct-writing 3D printing process can be effectively widened by developing the monodisperse metal nanoparticles with the size smaller than 1 mu m.

Disclosure of Invention

Aiming at the problems that the existing metal paste can not meet the requirement of a high-precision direct-writing 3D printing process with the thickness of below 10 mu m, and the nanometer metal paste is easy to agglomerate and difficult to disperse, has poor repeatability of the manufacturing process, can not realize commercialization and the like, the invention develops a novel nanometer metal 3D printing ink and provides a preparation method and application thereof.

The invention has the following conception: the invention realizes the synthesis of the monodisperse metal nanoparticles by the synergistic action of the double reducing agents and by controlling the dosage of the reducing agents, the polymer and the reaction temperature. Wherein, a strong reducing agent such as hydrazine hydrate is used for the metal nano-particles to quickly form crystal nuclei, the metal nano-particles with the particle size of 1-10 nanometers can be obtained by controlling the using amount of the strong reducing agent, and in the process, because the reaction temperature is lower, the weak reducing agent generally does not participate in the reaction and only plays a role in stabilizing the metal nano-particles with the particle size of 1-10 nanometers; then, with the rise of the reaction temperature, the activity of the weak reducing agent is obviously enhanced, so that the metal salt in the reaction system can be further reduced, and the metal particles subsequently reduced can uniformly grow on the surface of the crystal nucleus; in addition, the agglomeration rate of the metal nanoparticles can be slowed down during the reaction. In the reaction process, the polymer can also inhibit the further enlargement of the size of the large-size metal nanoparticles by coating the large-size metal nanoparticles, and can effectively inhibit the appearance of large-particle metal nanoparticles with the particle size of more than 1 mu m under the synergistic action of a weak reducing agent and a high-molecular polymer, so that the controllable synthesis of the metal nanoparticles is finally realized, and the effects of controllable size and monodispersity are achieved.

In order to achieve the object of the present invention, in a first aspect, the present invention provides a metal nanomaterial for nanometal 3D printing, the metal nanomaterial consisting of metal nanoparticles and ligands on the surface thereof; the metal nanoparticles have a particle size distribution interval of X + -Y, wherein X is 50-500nm, Y ≦ 20%.

The ligand may be selected from at least one of polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), triton, polyethylene glycol (PEG), and the like.

The metal nano material can be nano silver, nano copper, nano gold and the like.

In a second aspect, the present invention provides a method for preparing the metal nanomaterial, comprising the steps of:

A. dissolving metal salt in deionized water, adding a reducing agent I and a high molecular polymer, and uniformly mixing;

B. b, dropwise adding a reducing agent II solution into the reaction system obtained in the step A, and after dropwise adding is finished, heating to a specific temperature for reaction;

C. after the reaction is finished, cooling to room temperature, adding a poor solvent into the system to separate out a product, drying the product, redissolving the product in deionized water, and filtering the product for 1 to 5 times by using a filter screen with a proper pore diameter;

D. and drying the product to obtain the product.

The poor solvent may be an alcohol or a ketone having 1 to 6 carbon atoms.

Further, a step of adjusting the pH of the reaction system to 9-10 by using alkali liquor is also included between the step A and the step B.

Preferably, the alkali liquor is ammonia water, and other alkaline substances can also be used.

In the method, the specific temperature in the step B is 50-90 ℃, and the reaction time is 0.5-5 hours.

In the method, a filter screen with the aperture of 1-5 mu m is used in the step C. It should be noted that, for nanoparticle slurries of different sizes, filters of different pore sizes may be selected for filtration, wherein the pore size for filtration is generally 10 times or more the corresponding nanoparticle, for example, 100nm size particles, 1 μm pore size filter, 500nm size particles, or 5 μm pore size filter may be selected.

The metal salt can be a silver salt, a copper salt or a gold salt;

the reducing agent I can be at least one selected from hydramine with the carbon atom number of less than 10, dihydrogen hypophosphite, glucose, ascorbic acid and the like; preferably at least one of diethanolamine, sodium dihydrogen hypophosphite and butanol amine.

The high molecular polymer (ligand) can be selected from at least one of polyacrylic acid, polyvinylpyrrolidone, triton, polyethylene glycol and the like, and the molecular weight of the high molecular polymer is more than or equal to 5000Da. The main function of the method is to control the size of the metal nanoparticles.

The reducing agent II can be at least one selected from hydrazine hydrate, sodium borohydride, potassium borohydride, formaldehyde, formic acid, oxalic acid, citric acid and the like. The reducing agent II solution can be an aqueous or alcoholic solution of reducing agent II.

The mass ratio of the metal salt, the reducing agent I and the reducing agent II is 1 (0.2-1) to 0.5-5.

The mass ratio of the metal salt to the high molecular polymer is (2-10): 1.

In a third aspect, the invention provides nano metal 3D printing ink which is formed by mixing 50-90% of metal nano material and 10-50% of dispersing solvent, wherein the sum of the mass percentages of the metal nano material and the dispersing solvent is 100%.

The metal nano material is the metal nano material for nano metal 3D printing or the metal nano material prepared by the method.

The dispersion solvent may be a mixture of water and an alcohol having 4 carbon atoms, and the volume ratio of water to alcohol is 1.

Preferably, the alcohol is ethylene glycol or glycerol.

The printing ink can be used for processing metal wires with the diameter of more than or equal to 1 mu m, and the resistivity of the wires is less than 100 mu omega cm after the wires are sintered at the temperature of more than or equal to 150 ℃.

In a fourth aspect, the invention provides an application of the nano metal 3D printing ink in the field of conductive materials (printed electronic materials).

In one embodiment of the invention, the preparation method of the nano-silver 3D printing ink with the particle size of 80-120nm comprises the following steps:

(1) Taking 17g of silver nitrate, dissolving the silver nitrate in 50g of deionized water, sequentially adding 40g of diethanolamine and 2.5g of polyacrylic acid, and fully and uniformly stirring; the molecular weight of the polyacrylic acid is 50000Da;

(2) Dropwise adding 6mL of 80% hydrazine hydrate solution at the rate of 10mL/h, heating to 50 ℃ after dropwise adding, and reacting for 1h;

(3) After the reaction is finished, cooling to room temperature, adding about 300mL of ethanol, and separating out a product in a flocculent precipitate;

(4) Removing supernatant, air drying precipitate, re-dissolving in 15mL deionized water, filtering with 1 μm filter screen for 2 times, adding 40mL ethanol, and separating out product as flocculent precipitate;

(5) Discarding the supernatant, vacuumizing and drying the precipitate, and then adding a solvent mixed by water and ethylene glycol according to the volume ratio of 1:1 to obtain the nano-silver 3D printing ink with the particle size of 80-120 nm.

In another embodiment of the present invention, a method for preparing nano silver 3D printing ink with a particle size of 450 to 550nm includes the following steps:

(1) Taking 17g of silver nitrate, dissolving the silver nitrate in 50g of deionized water, sequentially adding 40g of diethanolamine and 5g of polyacrylic acid, and fully and uniformly stirring; the molecular weight of the polyacrylic acid is 5000Da;

(2) Dropwise adding 10mL of 5M sodium borohydride methanol solution at the rate of 10mL/h, heating to 80 ℃ after dropwise adding, and reacting for 30min;

(4) Discarding the supernatant, air-drying the precipitate, redissolving the precipitate in 15mL of deionized water, filtering the precipitate for 2 times by using a 5-micron filter screen, adding 40mL of ethanol, and separating out a product in the form of flocculent precipitate;

(5) And removing the supernatant, vacuumizing and drying the precipitate, and then proportionally adding a solvent mixed by water and ethylene glycol according to the volume ratio of 1:1 to obtain the nano-silver 3D printing ink with the particle size of 450-550 nm.

In another embodiment of the present invention, a method for preparing nano-copper 3D printing ink having a particle size of 45 to 55nm includes the steps of:

(1) Dissolving 25g of blue vitriod in 50g of deionized water, sequentially adding 20g of sodium dihydrogen hypophosphite and 4g of polyvinylpyrrolidone, adjusting the pH value to 9-10 by using ammonia water, and fully stirring and uniformly mixing; the molecular weight of the polyvinylpyrrolidone is 40000Da;

(2) Dropwise adding 10mL of 5M sodium borohydride methanol solution at the rate of 10mL/h, heating to 60 ℃ after dropwise adding, and reacting for 30min;

(3) After the reaction is finished, cooling to room temperature, adding about 300ml of acetone, and separating out a product in a flocculent precipitate;

(4) Removing supernatant, air drying precipitate, re-dissolving in 15mL deionized water, filtering with 1 μm filter screen for 2 times, adding 40mL acetone, and separating out product as flocculent precipitate;

(5) And removing the supernatant, vacuumizing and drying the precipitate, and then proportionally adding a solvent mixed by water and ethylene glycol according to the volume ratio of 1:1 to obtain the nano-copper 3D printing ink with the particle size of 45-55 nm.

In another embodiment of the present invention, a method for preparing nano-copper 3D printing ink with a particle size of 180-220nm comprises the following steps:

(1) Dissolving 25g of blue vitriol in 50g of deionized water, sequentially adding 10g of butanol amine and 4g of polyvinylpyrrolidone, adjusting the pH to 9-10 with ammonia water, and fully stirring and uniformly mixing; the molecular weight of the polyvinylpyrrolidone is 20000Da;

(2) Dropwise adding 10mL of 5M citric acid solution at the rate of 10mL/h, heating to 90 ℃ after dropwise adding, and reacting for 30min;

(4) Discarding the supernatant, drying the precipitate, redissolving the precipitate in 15mL of deionized water, filtering the precipitate for 2 times by using a 2-micron filter screen, adding 40mL of acetone, and separating out a product by using a flocculent precipitate;

(5) And removing supernatant, vacuumizing and drying the precipitate, and then adding a solvent mixed by water and glycol according to the volume ratio of 1:1 to obtain the nano-copper 3D printing ink with the particle size of 180-220 nm.

By the technical scheme, the invention at least has the following advantages and beneficial effects:

the nano metal particles prepared by the method can be uniformly dispersed in the solution, and the slurry can be used for a high-precision direct-writing 3D printing process with the particle size of less than 10 micrometers.

The invention successfully solves a series of technical problems of particle agglomeration, difficult dispersion, uncontrollable metal nanoparticle particle size, poor process repeatability and the like which are often generated in the preparation process of the nano conductive ink.

And thirdly, the nano metal 3D printing ink provided by the invention has the advantages that the average particle size of metal nanoparticles is between 50nm and 500nm, and the single control is realized. The distribution interval of the particle size is X + -Y, wherein X is 50-500nm, and Y is less than or equal to 20 percent.

Drawings

FIG. 1 is a graph showing the particle size distribution of 100nm Ag paste prepared in example 1 of the present invention.

FIG. 2 is a graph showing the particle size distribution of 500nm Ag paste prepared in example 2 of the present invention.

FIG. 3 is a graph showing the particle size distribution of 50nm Cu paste prepared in example 3 of the present invention.

FIG. 4 shows the particle size distribution of 200nm Cu slurry prepared in example 4 of the present invention.

FIG. 5 is a graph showing the particle size distribution of 400nm Ag paste in comparative example 1 of the present invention.

FIG. 6 is a graph showing the particle size distribution of 50nm Cu paste in comparative example 2 of the present invention.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are commercially available products.

The percent in the present invention means mass percent unless otherwise specified; but the percent of the solution, unless otherwise specified, refers to the grams of solute contained in 100mL of the solution.

EXAMPLE 1 preparation of 100nm Ag slurries

(1) Taking 17g of AgNO ₃ (100 mmol) is dissolved in 50g of deionized water, 40g of diethanolamine and 2.5g of PAA (MW 50,000) are added in sequence, and the mixture is fully stirred and mixed evenly;

(2) Dropwise adding 6ml (50 mmol) of hydrazine hydrate with the content of 80% at the speed of 10ml/h, heating to 50 ℃ after dropwise adding is finished, and reacting for 1h;

(3) Cooling to room temperature, adding about 300ml ethanol, and separating out a product in a flocculent precipitate;

(4) Removing supernatant, air drying, re-dissolving in 15ml deionized water, filtering with 1 μm filter screen twice, adding 40ml ethanol, and separating out product as flocculent precipitate;

(5) Vacuumizing and drying, and adding a mixed solvent of water and glycol =1:1 (volume ratio) in different proportions according to requirements to prepare 100nm Ag slurry with different solid contents.

The particle size distribution is 80-120nm, characterized by DLS (dynamic light scattering system, nanotrac NPA 252, microtrac, USA), and no particles with other sizes exist. The results are shown in FIG. 1.

The specific determination method is as follows: preparing a sample into a 10mg/mL solution by using deionized water, collecting data by using a Nanotrac NPA 252 device, and processing the data according to the particle distribution proportion of different size intervals after the test is finished.

EXAMPLE 2 preparation of 500nm Ag slurries

(1) Taking 17g of AgNO ₃ (100 mmol) is dissolved in 50g of deionized water, 40g of diethanolamine and 5g of PAA (MW 5,000) are added in sequence, and the mixture is fully stirred and mixed;

(2) Dropwise adding 10ml (20 mmol) of 5M sodium borohydride methanol solution at the speed of 10ml/h, and after dropwise adding, heating to 80 ℃ for reaction for 30min;

(4) Removing supernatant, air drying, re-dissolving in 15ml deionized water, filtering with 5 μm filter screen twice, adding 40ml ethanol, and separating out product as flocculent precipitate;

(5) Vacuumizing and drying, adding water with different proportions, namely ethylene glycol =1:1 (volume ratio) mixed solvent according to requirements, and preparing into 500nm Ag slurry with different solid contents

The particle size distribution is 450-550nm and no other particle exists by DLS characterization. The results are shown in FIG. 2.

EXAMPLE 3 preparation of 50nm Cu slurry

(1) 25g of CuSO ₄ ·5H ₂ Dissolving O (100 mmol) in 50g of deionized water, sequentially adding 20g of sodium dihydrogen hypophosphite and 4g of PVP (MW 40,000), adjusting the pH value to 9-10 by using ammonia water, and fully stirring and uniformly mixing;

(2) Dropwise adding 10ml (80 mmol) of 5M sodium borohydride methanol solution at the speed of 10ml/h, heating to 60 ℃ after dropwise adding is finished, and reacting for 30min;

(3) Cooling to room temperature, adding about 300ml acetone, and precipitating the product as flocculent precipitate

(4) Removing supernatant, air drying, re-dissolving in 15ml deionized water, filtering with 1 μm filter screen twice, adding 40ml acetone, and separating out product as flocculent precipitate;

(5) Vacuumizing and drying, and adding water with different proportions, namely ethylene glycol =1:1 (volume ratio) mixed solvent according to requirements to prepare 50nm Cu slurry with different solid contents.

The particle size distribution is 45-55nm and no other particles exist by DLS characterization. The results are shown in FIG. 3.

Example 4 preparation of 200nm Cu slurries

(1) 25g of CuSO was taken ₄ ·5H ₂ Dissolving O (100 mmol) in 50g of deionized water, sequentially adding 10g of butanol amine and 4g of PVP (MW 20,000), adjusting the pH value to 9-10 by using ammonia water, and fully stirring and uniformly mixing;

(2) Dropwise adding 10ml (100 mmol) of 5M citric acid solution at the rate of 10ml/h, heating to 90 ℃ after dropwise adding, and reacting for 30min;

(3) Cooling to room temperature, adding about 300ml of acetone, and separating out a product in a flocculent precipitate;

(4) Discarding supernatant, air drying, redissolving in 15ml deionized water, filtering twice with 2 μm filter screen, adding 40ml acetone, and separating out product as flocculent precipitate;

(5) Vacuumizing and drying, and adding water with different proportions, namely ethylene glycol =1:1 (volume ratio) mixed solvent according to requirements to prepare 200nm Cu slurry with different solid contents.

The particle size distribution is 180-220nm and no other particles exist by DLS characterization. The results are shown in FIG. 4.

Comparative example 1:

according to the literature Russo, A.etc., pen-on-Paper Flexible Electronics, adv.Mater.2011,23,3426-3430 (DOI: 10.1002/adma.201101328), 400nm Ag paste was synthesized, and the specific Synthesis steps are referred to in the section "Silver Ink Synthesis" of its Supporting Information.

The particle size distribution of the Ag paste is shown in fig. 5 by DLS characterization.

Comparative example 2:

according to the document Lee, Y.etc., large-scale synthesis of copper nanoparticles by chemical controlled reduction for applications of inkjet-printed electronics, nanotechnology,2008,19,415604 (DOI: 10.1088/0957-4484/19/41/560414), 50nm Cu slurry was synthesized, with specific synthetic steps see the "Materials and synthesis" paragraph of its Experimental details.

The particle size distribution of the Cu slurry is shown in fig. 6 by DLS characterization.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, it is intended that all such modifications and alterations be included within the scope of this invention as defined in the appended claims.

Claims

1. The metal nano material for the nano metal 3D printing is characterized by consisting of metal nano particles and ligands on the surfaces of the metal nano particles; the distribution interval of the particle size of the metal nano-particles is X +/-Y, wherein X is 50-500nm, and Y is less than or equal to 20 percent;

the ligand is at least one selected from polyacrylic acid, polyvinylpyrrolidone, triton and polyethylene glycol;

the metal nano material is nano silver, nano copper or nano gold;

the preparation method of the metal nano material comprises the following steps:

C. after the reaction is finished, cooling to room temperature, adding a poor solvent into the system to separate out a product, drying the product, redissolving the product in deionized water, and filtering the product for 1~5 times by using a filter screen with a proper pore diameter;

D. drying the product to obtain the product;

the poor solvent is alcohol or ketone with the carbon atom number of 1~6;

the specific temperature in the step B is 50-90 DEG C ^o C, the reaction time is 0.5 to 5 hours;

the reducing agent I is at least one selected from alcohol amine with the carbon atom number less than 10, dihydric hypophosphite, glucose and ascorbic acid;

the reducing agent II is at least one selected from hydrazine hydrate, sodium borohydride, potassium borohydride, formaldehyde, formic acid, oxalic acid and citric acid.

2. The metal nanomaterial according to claim 1, wherein the reducing agent I is at least one selected from diethanolamine, sodium dihydrogen hypophosphite and butanolamine.

3. The method for preparing a metal nanomaterial according to claim 1, comprising the steps of:

D. drying the product to obtain the product;

the poor solvent is alcohol or ketone with the carbon atom number of 1~6;

4. The method of claim 3, wherein the step A and the step B further comprise the step of adjusting the pH of the reaction system to 9 to 10 with an alkali solution.

5. The method of claim 4, wherein the base solution is ammonia.

6. The method according to claim 3, wherein a sieve having a pore size of 1 to 5 μm is used in step C.

7. The method according to claim 3, wherein the reducing agent I is at least one selected from diethanolamine, sodium dihydrogen hypophosphite and butanolamine.

8. The method of any one of claims 3-7, wherein the metal salt is a silver, copper or gold salt;

the high molecular polymer is at least one selected from polyacrylic acid, polyvinylpyrrolidone, triton and polyethylene glycol, and the molecular weight of the high molecular polymer is more than or equal to 5000Da.

9. The method according to claim 8, wherein the ratio of the amounts of the metal salt, the reducing agent I and the reducing agent II is 1 (0.2 to 1) to (0.5 to 5);

the mass ratio of the metal salt to the high molecular polymer is (2-10) to 1.

10. The nano metal 3D printing ink is characterized by comprising 50-90% of metal nano material and 10-50% of dispersing solvent, wherein the sum of the mass percentages of the metal nano material and the dispersing solvent is 100%;

wherein the metal nanomaterial is the metal nanomaterial of claim 1 or 2 or the metal nanomaterial prepared by the method of any one of claims 3 to 9;

the dispersion solvent is a mixture of water and an alcohol having a carbon number of <4, and the volume ratio of water to alcohol is 1.

11. The nanometal 3D printing ink according to claim 10, wherein the alcohol in the dispersion solvent is ethylene glycol or glycerol.

12. The nanometal 3D printing ink according to claim 10 or 11, characterized in that the printing ink can be used for processing metal wires of more than or equal to 1 μm, and the processing time is more than or equal to 150 ≥ m ^o Resistivity of the wire after sintering at C<100μΩ·cm。

13. Use of the nanometal 3D printing ink according to any one of claims 10 to 12 in the field of conductive materials.