WO2023000316A1

WO2023000316A1 - Composite conductive ink having high conductivity, and preparation method therefor

Info

Publication number: WO2023000316A1
Application number: PCT/CN2021/108196
Authority: WO
Inventors: 熊圣东
Original assignee: 宁波先锋新材料股份有限公司
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2023-01-26

Abstract

The present invention provides a composite conductive ink having high conductivity, comprising the following components in parts by weight: 100 parts of a resin; 15-35 parts of nano-silver; 2-10 parts of graphene; 50-70 parts of a solvent; 1-5 parts of a curing agent; and 1-4 parts of an additive. By adding nano-silver and graphene as conductive fillers, good conductivity of the ink can be ensured, the consumption of silver powder can be reduced, and cost can be reduced.

Description

A kind of composite conductive ink with high conductivity and preparation method thereof

technical field

The invention belongs to the technical field of conductive ink, and relates to a composite conductive ink with high conductivity and a preparation method thereof.

Background technique

Conductive ink is mainly used in printing conductive points and conductive lines, and it is widely used in keyboard electronic circuits, printed circuits, electrodes, electroplating bottom layers, etc. With the development of science and technology and the rapid development of the microelectronics industry, the prospects for conductive inks to be applied to printed circuits are extremely broad. Today, the main conductive inks used are gold-based conductive inks, silver-based conductive inks, copper-based conductive inks, and carbon-based conductive inks. Ink etc. According to statistics, the output value of silver-based conductive ink alone reached 2 billion US dollars in 2014, and it will further increase in the future. Therefore, it is necessary to increase the research and development of conductive ink to deeply tap the potential of conductive ink. , by combining conductive ink with nanotechnology, improving the conductive efficiency of conductive ink is the development direction of conductive ink for the development of conductive ink in the future.

The development of printed electronics has made the importance of conductive inks increasingly prominent. Printed electronics is a strategic emerging industry that applies traditional printing technology to the manufacture of electronic products. Its products are characterized by flexibility, portability, environmental protection, low cost, and large-area production. As a supplement and expansion of silicon-based electronics, the development The prospects are very bright.

Conductive ink is the basic material for the preparation of printed electronic devices. The composition and performance of conductive ink depend on the performance requirements of printed electronic products, and the performance of conductive ink determines the development direction of the preparation and processing technology of printed electronic conductive materials. The development of printed electronic products and conductive ink technology is characterized by technology integration. The market forecast is growing year by year, and the compound annual growth rate in many fields exceeds 45%, showing a rapid upward trend. Printed electronic products require conductive coatings with good conductivity, thin thickness and strong adhesion, so it is necessary to develop high-performance conductive inks.

Contents of the invention

Aiming at the defects in the prior art, the present invention provides a composite conductive ink, which uses graphene to replace part of the nano-silver, so as to improve the conductivity of the conductive graphite and reduce the cost of the conductive ink.

One aspect of the present invention provides a composite conductive ink with high conductivity, comprising the following components in parts by weight:

Resin: 100 parts; nano silver: 15-35 parts; graphene: 2-10 parts; solvent: 50-70 parts; curing agent: 1-5 parts; auxiliary agent: 1-4 parts.

In the present invention, nano-silver with excellent conductivity is added to the conductive ink, and the charge mobility of the nano-silver material is much higher than that of organic electronic materials, thereby effectively improving the conductivity of the conductive ink. At the same time, adding a small amount of graphene instead of nano-silver as a conductive filler can not only ensure good conductivity of the ink, but also reduce the consumption of silver powder and reduce costs.

Preferably, the resin is one or more of epoxy resin, polyurethane resin, alkyd resin, acrylic resin and photosensitive resin.

Preferably, the resin is epoxy resin. Epoxy resins contain epoxy groups, which can form three-dimensional cross-linked curing compounds under the action of curing agents and certain temperature conditions. It has the characteristics of high connection performance, small shrinkage rate, strong connection force, shrinkage rate, good stability, and excellent processing performance.

As preferably, the resin is bisphenol A epoxy resin, bisphenol F epoxy resin, glycidyl ester epoxy resin, aliphatic epoxy resin, acrylic modified epoxy resin, polyurethane modified epoxy resin and organosilicon One or more of epoxy resins.

Modification of epoxy resin, such as acrylic modified epoxy resin has the characteristics of acrylic plumpness, gloss, and good weather resistance; polyurethane modified epoxy resin has a good network structure, thereby improving the toughness of epoxy resin; Silicone modified epoxy resin can not only reduce the internal stress of epoxy resin, but also improve the toughness and high temperature resistance of epoxy resin, so that the resin has good toughness, compression molding performance, connection performance and impact resistance. Therefore, the conductive ink based on modified epoxy resin has good adhesion, heat resistance, flexibility, etc.

When the resin is epoxy resin, the curing agent is preferably one or more of dicyandiamide, polyamide, diethylenetriamine, ethylenediamine, diaminodiphenylmethane, maleic anhydride, and phenolic resin.

The curing agent undergoes a ring-opening or ring-closing reaction with the epoxy group of the epoxy resin to form a network-like three-dimensional polymer, so that some composite materials are wrapped in the network to improve the conductivity and adhesion of the conductive ink. For example, the curing of the primary amine is a nucleophilic addition reaction with the epoxy resin, and each active wave hydrogen can open an epoxy group to make it cross-linked and cured. Anhydride curing is the reaction of the carboxyl group on the epoxy resin with the acid anhydride to form an ester bond and carboxylic acid. The carboxylic acid adds to the epoxy group to form a carboxyl group. The generated carboxyl group continues to react with other anhydride groups. This reaction is repeated to form a body shape. polymer.

Preferably, the mass ratio of the resin to the total amount of nano-silver and graphene is 100:(25-35). When the mass ratio of the total amount of nano-silver and graphene to the resin is controlled as (25-35):100, the conductive ink has excellent conductivity and good comprehensive performance, which can meet the basic requirements of the flexible circuit of the membrane switch.

Preferably, the mass ratio of nano-silver and graphene is 1:(0.2-0.3). Nano-silver and graphene are mixed in this mass ratio, which effectively reduces the amount of silver used and costs on the basis of excellent electrical conductivity.

Preferably, the particle size range of the nano-silver is 20-100 nm.

Preferably, the graphene is one or more of unmodified graphene, chemically doped graphene, chemically modified graphene, and coupling agent modified graphene. Chemically doped graphene is one or more doped graphene of polyaniline, polyacetylene, polythiophene, polyparaphenylene and polypyrrole, and the chemically modified functional groups of chemically modified graphene are aniline, imidazole, One or more of benzenesulfonic acid group, thienyl group, furyl group and phenyl group.

The present invention is not particularly limited to the solvent in the conductive ink, and the conventional organic solvents used in conductive inks known to those skilled in the art can be used, such as methanol, ethanol, isopropanol, dimethylformamide, ethylene glycol, etc. Alcohol, propylene glycol, glycerin, toluene, xylene, ethyl acetate, propyl acetate, methyl formate, ethyl formate, ethyl lactate, ethyl valerate, acetone, methyl ethyl ketone, n-butanol, N, N -Dimethylformamide, N,N-dimethylacetamide, etc.

Preferably, the auxiliary agent includes: coupling agent, leveling agent, defoamer, accelerator and the like. The coupling agent can be listed as silane coupling agent or titanate coupling agent; the leveling agent can be listed as acrylic leveling agent, fluorine leveling agent, organosilicon leveling agent; The defoamer can be listed as organosiloxane defoamer, polyether defoamer; the accelerator can be listed as imidazole accelerator, including methylimidazole, 1-benzyl-2-methylimidazole and the like.

Another aspect of the present invention provides a method for preparing the highly conductive composite conductive graphite, comprising the following steps:

(1) earlier take each composition according to weight part;

(2) Add resin and a part of solvent, stir evenly at 200-500rpm, then add nano-silver, additives, curing agent, and another part of solvent, until the slurry is fully stirred and evenly made into a connecting material;

(3) Graphene is added in an organic solvent, then a coupling agent is added, and dispersed under ultrasonic and stirring conditions for 3 to 6 hours to obtain a graphene suspension. After centrifugation, the solid is dried to obtain a coupling agent-modified graphene;

(4) Add the coupling agent-modified graphene of step (3) to the connecting material of step (2), stir evenly, and grind 3 to 8 times with a three-roller machine to obtain the conductive ink.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the present invention, nano-silver and graphene are added as conductive fillers in the conductive ink, which can not only ensure the good conductivity of the ink but also reduce the consumption of silver powder and reduce the cost;

2. The present invention controls the mass ratio of nano-silver and graphene to 1: (0.2-0.3), on the basis of excellent electrical conductivity, effectively reduces the amount of silver used, and realizes the improvement of electrical conductivity and the reduction of cost;

3. The mass ratio of the total amount of nano-silver and graphene to the resin of the present invention is controlled to be (25-35): 100, and the conductive ink prepared has excellent conductivity and good overall performance, which can meet the basic requirements of the flexible circuit of the membrane switch;

4. The conductive graphite prepared by graphene/nano-silver also has the characteristics of good chemical stability and is not easy to be oxidized. Even if its surface is partially oxidized due to the preparation process or environmental factors, the generated oxide can also conduct electricity. Silver conductive ink is easy to prepare, stable in operation, and does not require additional anti-oxidation measures;

5. The graphene/nano-silver conductive ink of the present invention has a low sintering temperature, and the sintering temperature can be reduced to 70°C to 150°C. It can be deposited not only on PI, but also on plastics and flexible plates with low cost and low Tg. superior.

detailed description

The technical solutions of the present invention will be further described and illustrated through specific examples below. It should be understood that the specific examples described here are only used to help understand the present invention, and are not intended to specifically limit the present invention. Unless otherwise specified, the raw materials used in the examples of the present invention are commonly used raw materials in the art, and the methods used in the examples are conventional methods in the art.

Example 1

The composite conductive ink of this embodiment includes the following components by weight: bisphenol A epoxy resin: 100 parts, nano silver with a particle size range of 20-50 nm: 20 parts, graphene: 6 parts, organosiloxane defoamer: 2 parts, accelerator methylimidazole: 0.2 parts, dicyandiamide curing agent: 1.8 parts, solvent: 64.2 parts.

The preparation method of composite conductive graphite is as follows:

(1) Weigh 100 parts of bisphenol A epoxy resin, add 30 parts of methyl ethyl ketone, stir for 40 minutes at 300 rpm, add 20 parts of nano-silver, dimethylformamide solution containing dicyandiamide (in a ratio of 1:9 Dissolve 18 parts of dicyandiamide in N,N-dimethylformamide), add 2 parts of organosiloxane defoamer, 0.2 part of accelerator methylimidazole and 18 parts of ethyl acetate dropwise while stirring, Disperse for 1.5 hours at 800rpm in a high-speed disperser to obtain a link material;

(2) Weigh 6 parts of graphene, mix with 8 parts of methyl ethyl ketone, add 4 parts of coupling agent, and then perform ultrasonic dispersion at 35°C for 4 hours to obtain a graphene suspension, and then centrifuge at 2500r/min Separation, the centrifugation time is 4min, and the solid obtained by centrifugation is dried to obtain coupling agent modified graphene;

(3) Add the coupling agent-modified graphene obtained in step (2) to the connecting material obtained in step (1), and after fully stirring evenly, grind 3 times at a uniform speed with a three-roller machine to obtain conductive ink.

The obtained conductive ink was screen-printed on the PI film with a film thickness of about 10 microns, and the properties of the cured conductive film were measured as shown in Table 1.

Example 2

The composite conductive ink of this embodiment includes the following components by weight: bisphenol A epoxy resin: 100 parts, nano-silver with a particle size ranging from 20 to 50 nm: 25 parts, graphene: 5 parts, polyether defoamer: 2.2 parts , accelerator 1-benzyl-2-methylimidazole: 0.3 parts, maleic anhydride curing agent: 2 parts, solvent: 69 parts.

The preparation method of composite conductive graphite is as follows:

(1) Take by weighing 100 parts of bisphenol A epoxy resins, add 35 parts of methyl ethyl ketone, stir at 400 rpm for 35 minutes, add 25 parts of nano-silver, N, N-dimethylacetamide solution containing maleic anhydride (by 1 : 9 ratio (dissolve maleic anhydride in N, N-dimethylacetamide) 20 parts, add dropwise 2.2 parts of polyether defoamer, 0.3 parts of accelerator 1-benzyl-2-methyl Imidazole and 16 parts of ethyl acetate were dispersed in a high-speed disperser at 1000rpm for 1 hour to obtain a link material;

(2) Weigh 5 parts of graphene, mix with 8 parts of methyl ethyl ketone, add 6 parts of coupling agent, and then perform ultrasonic dispersion at 37°C for 5 hours to obtain a graphene suspension, and then centrifuge at 3000r/min Separation, the centrifugation time is 3min, and the solid obtained by centrifugation is dried to obtain coupling agent modified graphene;

(3) Add the coupling agent-modified graphene obtained in step (2) to the connecting material obtained in step (1), and after fully stirring, grind 4 times at a uniform speed with a three-roller machine to obtain conductive ink.

Example 3

The composite conductive ink of this embodiment includes the following components by weight: polyurethane modified epoxy resin: 100 parts, nano-silver with a particle size ranging from 20 to 50 nm: 28 parts, graphene: 7 parts, polyether defoamer: 2.5 parts , accelerator methylimidazole: 0.2 parts, diethylenetriamine curing agent: 2.5 parts, solvent: 57 parts.

The preparation method of composite conductive graphite is as follows:

(1) Weigh 100 parts of urethane-modified epoxy resin, add 42 parts of butanone, stir for 40 minutes at 400 rpm, add 28 parts of nano-silver, 2.5 parts of diethylenetriamine curing agent, and drop 2.5 parts of polyethylene glycol while stirring. Ether defoamer, 0.2 parts of accelerator methylimidazole and 15 parts of ethyl acetate were dispersed in a high-speed disperser at 1200 rpm for 1 hour to obtain a link material;

(2) Weigh 7 parts of graphene, mix with 10 parts of methyl ethyl ketone, add 6 parts of coupling agent, and then perform ultrasonic dispersion at 35°C for 6 hours to obtain a graphene suspension, and then centrifuge at 3000r/min , the centrifugation time is 2min, and the solid obtained by centrifugation is dried to obtain coupling agent-modified graphene;

Example 4

The difference between this example and Example 1 is that the composite conductive ink of Example 4 includes the following components by weight: bisphenol A epoxy resin: 100 parts, nano-silver with a particle size ranging from 20 to 50 nm: 22 parts, graphene: 4 parts, organosiloxane defoamer: 2 parts, accelerator methylimidazole: 0.2 parts, dicyandiamide curing agent: 1.8 parts, solvent: 64.2 parts. Others are the same as in Example 1.

Example 5

The difference between this example and Example 1 is that the composite conductive ink of Example 5 includes the following components by weight: bisphenol A epoxy resin: 100 parts, nano silver with a particle size ranging from 20 to 50 nm: 18 parts, graphene: 8 parts, organosiloxane defoamer: 2 parts, accelerator methylimidazole: 0.2 parts, dicyandiamide curing agent: 1.8 parts, solvent: 64.2 parts. Others are the same as in Example 1.

Comparative example 1

The composite conductive ink of comparative example 1 comprises the following components by weight: bisphenol A epoxy resin: 100 parts, nano-silver with a particle size range of 20 to 50 nm: 26 parts, organosiloxane defoamer: 2 parts, accelerator A Kiimidazole: 0.2 parts, dicyandiamide curing agent: 1.8 parts, solvent: 64.2 parts.

The preparation method of composite conductive graphite is as follows:

Take by weighing 100 parts of bisphenol A epoxy resins, add 30 parts of butanone, stir at 300 rpm for 40 minutes, add 26 parts of nano-silver, dimethylformamide solution containing dicyandiamide (dicyandiamide in a ratio of 1:9 Amine dissolved in N,N-dimethylformamide) 18 parts, while stirring, add 2 parts of organosiloxane defoamer, 0.2 parts of accelerator methylimidazole and 18 parts of ethyl acetate, in the high-speed disperser Disperse in 800rpm for 1.5 hours to obtain the connecting material; use a three-roll machine to grind 3 times at a constant speed to obtain the conductive ink.

Comparative example 2

The composite conductive ink of comparative example 2 includes the following components by weight: bisphenol A epoxy resin: 100 parts, nano silver with a particle size ranging from 20 to 50 nm: 20 parts, graphene: 6 parts, organosiloxane defoamer: 2 parts, accelerator methylimidazole: 0.2 parts, dicyandiamide curing agent: 1.8 parts, solvent: 64.2 parts.

The preparation method of composite conductive graphite is as follows:

(2) 6 parts of graphene are joined in the connecting material that step (1) obtains, and after fully stirring, grind 3 times at a constant speed with a three-roller machine, obtain conductive ink.

The conductive ink performance of table 1 embodiment 1-5 and comparative example 1-2

1. Adhesion test, GB/T9286-88 national standard, 100-grid knife plus 3M glue, full inspection, 0-5 grades.

2. Volume resistivity, GB/T1410-2006 national standard. Resistance multimeter, full inspection, the test distance is 20mm.

3. Anti-alcohol wiping, dust-free cloth/alcohol, full inspection, QB/569-1983. Dip a little alcohol with a dust-free cloth, and wipe back and forth with 1kg·f 50 times on the screen printing surface of the conductive ink. If there is no mimeograph, it is good.

4. Fineness, GB/T13217.3-2008. Scraper fineness meter, full inspection.

As can be seen from Table 1, the adhesion and conductivity of Examples 1-3 are excellent, and Example 1 uses nano-silver and graphene in a suitable ratio as the conductive filler, and the conductivity may be comparable to that of using nano-silver as the conductive filler. The ink (see comparative example 1), and the cost of embodiment 1 reduces greatly. The graphene in the conductive graphite of Comparative Example 2 was not treated in any way, which resulted in poor compatibility between the graphene and the matrix resin, which affected the adhesion and conductivity of the conductive ink.

Finally, it should be noted that the specific embodiments described herein are only examples to illustrate the spirit of the present invention, rather than limiting the implementation of the present invention. Those skilled in the technical field to which the present invention belongs may make various modifications or supplements to the described embodiments, or replace them in similar ways, and it is not necessary and impossible to give a full example of all the embodiments here. And these obvious changes or changes derived from the essential spirit of the present invention still belong to the protection scope of the present invention, and interpreting them as any kind of additional limitation all violates the spirit of the present invention.

Claims

A kind of composite conductive ink with high conductivity is characterized in that, described composite conductive ink comprises following components by weight:

Resin: 100 parts; nano silver: 15-35 parts; graphene: 2-10 parts; solvent: 50-70 parts; curing agent: 1-5 parts; auxiliary agent: 1-4 parts.
The composite conductive ink with high conductivity according to claim 1, wherein the resin is one or more of epoxy resin, polyurethane resin, alkyd resin, acrylic resin, and photosensitive resin.
The composite conductive ink with high conductivity according to claim 1 or 2, wherein the resin is epoxy resin.
The composite conductive ink with high conductivity according to claim 3, wherein the epoxy resin is bisphenol A epoxy resin, bisphenol F epoxy resin, glycidyl ester epoxy resin, aliphatic ring One or more of epoxy resin, acrylic modified epoxy resin, polyurethane modified epoxy resin and silicone epoxy resin.
The composite conductive ink with high conductivity according to claim 1, characterized in that the mass ratio of the total amount of nano-silver and graphene to resin is (25-35):100.
The composite conductive ink with high conductivity according to claim 1 or 5, characterized in that the mass ratio of nano-silver to graphene is 1: (0.2-0.3).
The composite conductive ink with high conductivity according to claim 1, characterized in that the particle size range of the nano-silver is 20-100 nm.
The composite conductive ink with high conductivity according to claim 1, wherein said Graphene is unmodified Graphene, chemically doped Graphene, chemically modified Graphene, coupling agent modified Graphene one or more of.
The composite conductive ink with high conductivity according to claim 1, wherein the curing agent is dicyandiamide, polyamide, diethylenetriamine, ethylenediamine, diaminodiphenylmethane, malay One or more of acid anhydrides and phenolic resins.
A kind of preparation method of the composite conductive graphite of high conductivity as claimed in claim 1, comprises the following steps:

(1) earlier take each composition according to the weight part of claim 1;

(2) Add resin and a part of solvent, stir evenly at 200-500rpm, then add nano-silver, auxiliary agent, curing agent, and another part of solvent respectively until the slurry is fully stirred and evenly made into a connecting material;

(3) Graphene is added in an organic solvent, then a coupling agent is added, and dispersed under ultrasonic and stirring conditions for 3 to 6 hours to obtain a graphene suspension. After centrifugation, the solid is dried to obtain a coupling agent-modified graphene;

(4) Add the coupling agent-modified graphene of step (3) to the connecting material of step (2), stir evenly, and grind 3 to 8 times with a three-roll machine to obtain the conductive ink.