WO2022262801A1

WO2022262801A1 - Nano-metal 3d printing ink and application thereof

Info

Publication number: WO2022262801A1
Application number: PCT/CN2022/099106
Authority: WO
Inventors: 陈小朋
Original assignee: 芯体素(杭州)科技发展有限公司
Priority date: 2021-06-18
Filing date: 2022-06-16
Publication date: 2022-12-22
Also published as: CN113579229B; TW202302774A; TWI823429B; CN113579229A

Abstract

Nano-metal 3D printing ink and an application thereof. By means of the synergistic effect of dual reducing agents, the present invention achieves the controllable synthesis of metal nano particles and achieve the effects of a controllable size and monodispersity, wherein a strong reducing agent, such as hydrazine hydrate, is used for rapid formation of the metal nano particles, and a weak reducing agent, such as diethanolamine, is used for slow reduction and agglomeration of surface metal particles of small-particle size metal nano particles. The prepared nano metal particles can be uniformly dispersed in a solution, and the slurry can be used for a high-precision direct-writing 3D printing process below 10 μm.

Description

Nano metal 3D printing ink and its application

technical field

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

Background technique

In recent years, with the maturity of metal 3D printing technology, compared with traditional technology, it can shorten the new product development and realization cycle, efficiently form more complex structures, realize integration, lightweight design, and achieve excellent Mechanical properties and other aspects have shown incomparable advantages. With the expansion of the industrialization scale of metal 3D printing, problems such as fewer types of metal powder materials, lower quality, and insufficient supply in the market have become increasingly apparent. For example, the most common commercial silver paste on the market generally uses micron-level silver flakes. When the screen printing process is adopted, the line width and line spacing have reached 60-70 μm, while the laser engraving technology, the line width and line spacing It will still be at 30-40μm. Due to the problems of large particle size, easy agglomeration, and difficult dispersion of commercial silver paste, it is currently unable to meet the high-precision direct writing 3D printing process below 10 μm.

Therefore, the development of monodisperse metal nanoparticles with a size of less than 1 μm can effectively improve the scope of application of the high-precision direct writing 3D printing process.

technical problem

The present invention aims at the problems that the existing metal paste cannot meet the high-precision direct writing 3D printing process below 10 μm, and the nano-metal paste is often easy to agglomerate, difficult to disperse, poor in repeatability of the manufacturing process, and unable to realize commercialization, etc., and develops a new type of nano Metal 3D printing ink, and its preparation method and application are provided.

technical solution

The concept of the present invention is as follows: the present invention realizes the synthesis of monodisperse metal nanoparticles through the synergistic effect of double reducing agents, and controls the dosage of reducing agents, polymers and reaction temperature. Among them, strong reducing agents such as hydrazine hydrate are used to quickly form crystal nuclei on metal nanoparticles. By controlling the amount of strong reducing agents, metal nanoparticles with particle sizes between 1 and 10 nanometers can be obtained. During this process, due to the reaction The temperature is low, and the weak reducing agent generally does not participate in the reaction, and only plays the role of stabilizing the metal nanoparticles of 1-10 nanometers; later, as the reaction temperature increases, the activity of the weak reducing agent will become significantly stronger, so that it can The metal salt in the reaction system is further reduced, so that the subsequently reduced metal particles can grow uniformly on the surface of the crystal nucleus; in addition, the agglomeration rate of the metal nanoparticles can be slowed down during the reaction process. During the reaction process, the polymer can also suppress the further increase in size by coating the large-sized metal nanoparticles. The emergence of granular metal nanoparticles finally realizes the controllable synthesis of metal nanoparticles, and achieves the effect of controllable size and monodispersity.

In order to achieve the purpose of the present invention, in a first aspect, the present invention provides a metal nanomaterial for nano-metal 3D printing, the metal nanomaterial is composed of metal nanoparticles and ligands on their surfaces; the particle size of the metal nanoparticles The distribution interval is X±Y, wherein, X is 50-500nm, Y≤20%X.

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

The metal nanomaterials may 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 following steps:

A. Dissolve metal salt in deionized water, add reducing agent I and polymer, and mix well;

B. Add the reducing agent II solution dropwise to the reaction system obtained in step A. After the dropwise addition, heat up to a specific temperature for reaction;

C. After the reaction is finished, cool down to room temperature, add a poor solvent to the system to precipitate the product, redissolve the product in deionized water after drying, and filter it with a suitable pore size filter for 1 to 5 times;

D. The product is obtained after drying.

The poor solvent may be alcohol or ketone with 1-6 carbon atoms.

Further, between steps A and B, a step of adjusting the pH of the reaction system to 9-10 with lye is also included.

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

In the aforementioned method, the specified temperature in step B is 50°C-90°C, and the reaction time is 0.5-5 hours.

In the aforementioned method, a filter screen with a pore size of 1-5 μm is used in step C. It should be noted that different sizes of nanoparticle slurries can be filtered by filters with different pore sizes. Generally, the pore size of the filter is 10 times or more than that of the corresponding nanoparticles. The filter screen, the particle size of 500nm, can choose the filter screen with pore size of 5μm.

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

The reducing agent I can be selected from at least one of alcoholamines, dihydrogen hypophosphite, glucose, ascorbic acid, etc. with carbon atoms<10; preferably diethanolamine, sodium dihydrogen hypophosphite, butanolamine at least one of .

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

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

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

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

In a third aspect, the present invention provides a nano-metal 3D printing ink, which is composed of 50-90% metal nano-materials and 10-50% dispersing solvent, and the sum of their mass percentages is 100%.

Wherein, the metal nanomaterial is the metal nanomaterial for nanometal 3D printing or the metal nanomaterial prepared according to the above method.

The dispersing solvent may be a mixture of water and an alcohol with a carbon number <4, and the volume ratio of water to alcohol is 1:10˜10:1.

Preferably, the alcohol is ethylene glycol or glycerol.

The printing ink can be used for processing metal wires of ≥1 μm, and after sintering at a temperature of ≥150° C., the resistivity of the wires is less than 100 μΩ·cm.

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

In a specific embodiment of the present invention, the preparation method of the nano-silver 3D printing ink whose particle size is 80-120nm comprises the following steps:

(1) Take 17g of silver nitrate, dissolve it in 50g of deionized water, add 40g of diethanolamine and 2.5g of polyacrylic acid in turn, and stir well; the molecular weight of the polyacrylic acid is 50000Da;

(2) Add 6mL of 80% hydrazine hydrate solution dropwise at a rate of 10mL/h. After the dropwise addition, raise the temperature to 50°C and react for 1h;

(3) After the reaction, cool down to room temperature, add about 300mL of ethanol, and the product precipitates out as floc;

(4) Discard the supernatant, dry the precipitate, redissolve in 15mL of deionized water, filter twice with a 1μm filter, add 40mL of ethanol, and the product precipitates out as a flocculent precipitate;

(5) The supernatant was discarded, the precipitate was vacuum-dried, and then a solvent mixed with water and ethylene glycol at a volume ratio of 1:1 was added in proportion to obtain a nano-silver 3D printing ink with a particle size of 80-120nm.

In another specific embodiment of the present invention, the preparation method of the nano-silver 3D printing ink whose particle size is 450-550nm comprises the following steps:

(1) Get 17g silver nitrate, be dissolved in 50g deionized water, add 40g diethanolamine and 5g polyacrylic acid successively, fully stir and mix; The molecular weight of described polyacrylic acid is 5000Da;

(2) Add 10mL of 5M sodium borohydride methanol solution dropwise at a rate of 10mL/h. After the dropwise addition, raise the temperature to 80°C and react for 30min;

(4) Discard the supernatant, dry the precipitate, redissolve in 15 mL of deionized water, filter twice with a 5 μm filter, add 40 mL of ethanol, and the product precipitates out as flocculent precipitates;

(5) The supernatant was discarded, the precipitate was vacuum-dried, and then a solvent mixed with water and ethylene glycol at a volume ratio of 1:1 was added in proportion to obtain a nano-silver 3D printing ink with a particle size of 450-550nm.

In another specific embodiment of the present invention, the preparation method of nano-copper 3D printing ink with a particle size of 45-55nm comprises the following steps:

(1) Get 25g of copper sulfate pentahydrate, dissolve it in 50g of deionized water, add 20g of sodium dihydrogen hypophosphite and 4g of polyvinylpyrrolidone successively, adjust the pH to 9-10 with ammonia water, and fully stir and mix; the polyvinylpyrrolidone The molecular weight is 40000Da;

(2) Add 10mL of 5M sodium borohydride methanol solution dropwise at a rate of 10mL/h. After the dropwise addition, raise the temperature to 60°C and react for 30min;

(3) After the reaction is finished, cool down to room temperature, add about 300ml of acetone, and the product will be precipitated out in flocculent form;

(4) Discard the supernatant, dry the precipitate, redissolve in 15 mL of deionized water, filter twice with a 1 μm filter, add 40 mL of acetone, and the product precipitates out as flocculent precipitates;

(5) The supernatant was discarded, the precipitate was vacuum-dried, and then a solvent mixed with water and ethylene glycol at a volume ratio of 1:1 was added in proportion to obtain a nano-copper 3D printing ink with a particle size of 45-55nm.

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

the (1) Get 25g copper sulfate pentahydrate, dissolve in 50g deionized water, add 10g butanolamine and 4g polyvinylpyrrolidone successively, adjust the pH to 9-10 with ammonia water, fully stir and mix; the molecular weight of the polyvinylpyrrolidone 20000Da;

(2) Add 10mL of 5M citric acid solution dropwise at a rate of 10mL/h. After the dropwise addition, raise the temperature to 90°C and react for 30min;

the (3) After the reaction is finished, cool down to room temperature, add about 300ml of acetone, and the product will be precipitated out in flocculent form;

(4) Discard the supernatant, dry the precipitate, redissolve in 15 mL of deionized water, filter twice with a 2 μm filter, add 40 mL of acetone, and the product precipitates out as flocculent precipitates;

(5) The supernatant was discarded, the precipitate was vacuum-dried, and then a solvent mixed with water and ethylene glycol at a volume ratio of 1:1 was added in proportion to obtain a nano-copper 3D printing ink with a particle size of 180-220nm.

Beneficial effect

By virtue of the above technical solutions, the present invention has at least the following advantages and beneficial effects:

(1) The nano-metal particles prepared by the present invention can be uniformly dispersed in the solution, and this type of slurry can be used in a high-precision direct-writing 3D printing process below 10 μm.

(2) The present invention successfully solves a series of technical problems such as particle agglomeration, difficulty in dispersion, uncontrollable particle size of metal nanoparticles and poor process repeatability in the preparation process of nano conductive ink. The nano conductive ink prepared by the present invention, metal The size of the nanoparticles is highly controllable and the process repeatability is good, so as to meet the needs of industrial production.

(3) The nano-metal 3D printing ink provided by the present invention, wherein the average particle size of the metal nanoparticles is between 50nm and 500nm, which is single and controllable. The particle size distribution range is X±Y, where X is 50-500nm, and Y≤20%X.

Description of drawings

Fig. 1 is the particle size distribution of the 100nm Ag slurry prepared in Example 1 of the present invention.

Fig. 2 is the particle size distribution of the 500nm Ag slurry prepared in Example 2 of the present invention.

Fig. 3 is the particle size distribution of the 50nm Cu slurry prepared in Example 3 of the present invention.

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

Fig. 5 is the particle size distribution of the 400nm Ag slurry in Comparative Example 1 of the present invention.

FIG. 6 shows the particle size distribution of the 50 nm Cu slurry in Comparative Example 2 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present 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 all commercially available products.

The percentage sign "%" involved in the present invention refers to the mass percentage unless otherwise specified; but the percentage of the solution refers to the grams of solute contained in 100 mL of the solution, unless otherwise specified.

Preparation of Example 1 100nm Ag slurry

(1) Take 17g of AgNO ₃ (100mmol), dissolve it in 50g of deionized water, add 40g of diethanolamine and 2.5g of PAA (MW50,000) in sequence, and stir well;

(2) Add 6 ml (50 mmol) of 80% hydrazine hydrate dropwise at a rate of 10 ml/h. After the addition is completed, heat up to 50° C. and react for 1 h;

(3) drop to room temperature, add about 300ml ethanol, and the product is separated out with flocculent precipitation;

(4) discard the supernatant, after drying, redissolve in 15ml of deionized water, filter twice with a 1 μm filter, add 40ml of ethanol, and the product precipitates out as floc;

(5) Vacuum drying, according to requirements, add different proportions of water: ethylene glycol = 1:1 (volume ratio) mixed solvent, can be configured into 100nm of different solid content Ag slurry.

After DLS (Dynamic Light Scattering System, Nanotrac NPA 252, Microtrac, USA), the particle size distribution is 80-120nm, and no other size particles exist. The results are shown in Figure 1.

The specific determination method is as follows: the sample is prepared into a 10 mg/mL solution with deionized water, and the Nanotrac The NPA252 equipment collects data, and after the test is completed, the data is processed according to the distribution ratio of particles in different size intervals.

Embodiments of the present invention

The preparation of embodiment 2 500nm Ag slurry

(1) Take 17g of AgNO3 (100mmol), dissolve it in 50g of deionized water, add 40g of diethanolamine, 5g of PAA (MW5,000) in turn, stir and mix well;

(2) Add 10ml (20mmol) of 5M sodium borohydride methanol solution dropwise at a rate of 10ml/h. After the dropwise addition, heat up to 80°C and react for 30min;

(4) discard the supernatant, after drying, redissolve in 15ml of deionized water, filter twice with a 5 μm filter, add 40ml of ethanol, and the product precipitates out as floc;

(5) Vacuum drying, according to requirements, add different proportions of water: ethylene glycol = 1:1 (volume ratio) mixed solvent, can be configured into 500nm with different solid content Ag slurry

Characterized by DLS, the particle size distribution is 450-550nm, and no other size particles exist. The results are shown in Figure 2.

Preparation of Example 3 50nm Cu slurry

(1) Take 25g of CuSO ₄ ·5H ₂ O (100mmol), dissolve it in 50g of deionized water, add 20g of sodium dihydrogen hypophosphite, 4g of PVP (MW 40,000) in turn, adjust the pH to 9-10 with ammonia water, and mix well uniform;

(2) Add 10ml (80mmol) of 5M sodium borohydride methanol solution dropwise at a rate of 10ml/h. After the dropwise addition, heat up to 60°C and react for 30min;

(3) Cool down to room temperature, add about 300ml acetone, the product precipitates out as flocculent

(4) discard the supernatant, after drying, redissolve in 15ml of deionized water, filter twice with a 1 μm filter, add 40ml of acetone, and the product precipitates out as floc;

(5) Vacuum drying, adding water in different proportions according to requirements: a mixed solvent of ethylene glycol=1:1 (volume ratio), which can be configured into 50nm with different solid content Cu slurry.

Characterized by DLS, the particle size distribution is 45-55nm, and no other size particles exist. The results are shown in Figure 3.

Preparation of Example 4 200nm Cu slurry

(1) Take 25g of CuSO ₄ ·5H ₂ O (100mmol), dissolve it in 50g of deionized water, add 10g of butanolamine, PVP (MW 20,000) 4g in turn, adjust the pH to 9-10 with ammonia water, stir and mix well;

(2) Add 10ml (100mmol) of 5M citric acid solution dropwise at a rate of 10ml/h. After the dropwise addition, heat up to 90°C and react for 30min;

(3) drop to room temperature, add about 300ml acetone, and the product precipitates out with floc;

(4) discard the supernatant, after drying, redissolve in 15ml of deionized water, filter twice with a 2 μm filter, add 40ml of acetone, and the product precipitates out as floc;

(5) Vacuum drying, adding different proportions of water according to requirements: ethylene glycol = 1:1 (volume ratio) mixed solvent, can be configured into 200nm with different solid content Cu slurry.

Characterized by DLS, the particle size distribution is in the range of 180-220nm, and no particles of other sizes exist. The results are shown in Figure 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), synthesized 400nm Ag slurry, specific synthesis steps refer to "Silver Ink Synthesis" paragraph.

Characterized by DLS, the particle size distribution of the Ag slurry is shown in Figure 5.

comparative example 2 :

According to the literature Lee, Y.etc, Large-scale synthesis of copper nanoparticles Bychemically controlled reduction for applications of inkjet-printedelectronics, Nanotechnology, 2008, 19, 415604 (DOI: 10.1088/0957-4484/19/41/415604), synthesized 50nm Cu slurry, the specific synthesis steps refer to "Materials" in its Experimental details andsynthesis" paragraph.

Characterized by DLS, the particle size distribution of Cu slurry is shown in Figure 6.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims

Metal nanomaterials for nanometal 3D printing, characterized in that the metal nanomaterials are composed of metal nanoparticles and ligands on their surfaces; the particle size distribution interval of the metal nanoparticles is X±Y, where X is 50-500nm, Y≤20%X;

The ligand is selected from at least one of polyacrylic acid, polyvinylpyrrolidone, triton, polyethylene glycol;

The metal nanomaterial is nano-silver, nano-copper or nano-gold.
The preparation method of the described metallic nanomaterial of claim 1, is characterized in that, comprises the following steps:

A. Dissolve metal salt in deionized water, add reducing agent I and polymer, and mix well;

B. Add the reducing agent II solution dropwise to the reaction system obtained in step A. After the dropwise addition, heat up to a specific temperature for reaction;

C. After the reaction is finished, cool down to room temperature, add a poor solvent to the system to precipitate the product, redissolve the product in deionized water after drying, and filter it with a suitable pore size filter for 1 to 5 times;

D, the product is obtained after drying;

The poor solvent is alcohol or ketone with 1-6 carbon atoms.
The method according to claim 2, characterized in that, between steps A and B, a step of adjusting the pH of the reaction system to 9-10 with lye is also included.
The method according to claim 2, characterized in that the specified temperature in step B is 50°C-90°C, and the reaction time is 0.5-5 hours.
The method according to claim 2, characterized in that a filter screen with a pore size of 1-5 μm is used in step C.
The method according to any one of claims 2-5, wherein the metal salt is a silver salt, a copper salt or a gold salt;

The reducing agent I is selected from at least one of alkanolamine, dihydrogen hypophosphite, glucose, and ascorbic acid with a carbon number<10;

The high molecular polymer is selected from at least one of polyacrylic acid, polyvinylpyrrolidone, triton, and polyethylene glycol, and the molecular weight of the high molecular polymer is ≥ 5000Da;

The reducing agent II is at least one selected from hydrazine hydrate, sodium borohydride, potassium borohydride, formaldehyde, formic acid, oxalic acid, and citric acid.
The method according to claim 6, characterized in that the ratio of the amount of the metal salt, reducing agent I and reducing agent II is 1:(0.2～1):(0.5～5);

The mass ratio of the metal salt to the polymer is (2-10):1.
The nano-metal 3D printing ink is characterized in that the printing ink comprises 50-90% metal nano-materials and 10-50% dispersing solvent mixed, and the sum of their mass percentages is 100%;

Wherein, the metal nanomaterial is the metal nanomaterial according to claim 1 or the metal nanomaterial prepared according to the method described in any one of claims 2-7;

The dispersing solvent is a mixture of water and an alcohol with carbon number<4, and the volume ratio of water to alcohol is 1:10˜10:1.
The nano-metal 3D printing ink according to claim 8, characterized in that, the nano-metal 3D printing ink can be used to process metal wires ≥ 1 μm, and after sintering at a temperature ≥ 150°C, the resistivity of the wires is <100 μΩ· cm.
The application of the nano-metal 3D printing ink described in claim 8 or 9 in the field of conductive materials.