CN110272664A - A kind of fractal structure silver particles electrically conductive ink of silk-screen printing and preparation method thereof - Google Patents

Abstract

The present invention relates to fractal structure silver particles electrically conductive inks of a kind of silk-screen printing and preparation method thereof, according to parts by weight, raw material includes: 2 parts~6 parts of fractal structure silver particles, 10 parts~45 parts of hydroxypropyl methyl cellulose, 0.002 part~1 part of fluorinated surfactant, 0.01 part~1 part of defoaming agent, 1 part~10 parts and 20 parts~50 parts of water of isopropanol.The advantages of fractal structure silver particles electrically conductive ink of the present invention has film forming speed fast, good film-forming property and excellent electric conductivity is 0.0818~0.6 Ω using conductive paper sheet resistance made from the electrically conductive ink.

Description

A kind of fractal structure silver particle conductive ink for screen printing and preparation method thereof

technical field

The invention belongs to the technical field of printing ink, and relates to a fractal structure silver particle conductive ink for screen printing and a preparation method thereof.

Background technique

In recent years, both the basic research and applied research of printed electronics technology have attracted the attention of a large number of researchers. Traditional electronic device preparation methods are mainly photolithography, vacuum evaporation and chemical plating, etc. The preparation process is relatively complicated, and the required equipment is relatively expensive, making it difficult to realize the preparation of large-area electronic devices. Compared with traditional electronic device preparation methods, printed electronics technology has the advantages of rapidity, low cost and environmental friendliness.

One of the key technologies of printed electronics is the need to prepare new environmentally friendly and low-cost conductive inks. Conductive inks are generally divided into two categories, one is conductive inks for inkjet printing, and the other is conductive polymer composites for screen printing. Compared with inkjet printing, screen printing has the advantage of not requiring expensive inkjet equipment, low cost and simple operation. Conductive ink is usually a multi-component system composed of conductive components, solvents and various additives. There are three main types of conductive components: metal nanomaterials, carbon materials and conductive polymers. Conductive polymer composites usually consist of a polymer matrix and conductive fillers.

Although the polymer matrix is generally electrically insulating, by adding conductive fillers such as metal nanowires, carbon nanotubes, graphene, etc. into the polymer matrix, the conductive fillers are connected to each other to form a conductive path, which can transform it from an insulator to a conductor. These conductive paths can be achieved by two different mechanisms: mechanical contact between the conductive fillers and electron tunneling - the conductive materials are not in contact but close enough to allow electrons to pass through the polymer matrix. Although increasing the mass fraction of conductive fillers in the composites can lead to higher electrical conductivity, it also reduces the mechanical properties of the composites. At the same time, the more the amount of conductive filler added, the higher the cost. Therefore, the key to saving cost is to use a small amount of conductive filler to form a conductive network in the polymer matrix.

Contents of the invention

The purpose of the present invention is to overcome the problems existing in the prior art, provide a kind of fractal structure silver particle conductive ink for screen printing and its preparation method, can form conductive ink with a small amount of conductive filler, ensure conductivity.

In order to achieve the above object, ink of the present invention adopts following technical scheme:

It is characterized by:

In parts by weight, the raw materials include:

Further, the particle size of the fractal structured silver particles is 5-15 μm.

Further, the fluorosurfactant adopts Zonyl FC-300 fluorosurfactant, and the model of the defoamer is BASF MO-2170.

Further, the fractal silver particles have a three-dimensional dendrite structure.

The technical scheme of preparation method of the present invention is: comprise the following steps:

(1) first add hydroxypropyl methylcellulose to 18 to 48 parts of water and mix uniformly to obtain an aqueous solution of hydroxypropyl methylcellulose;

(2) Add fluorosurfactant and antifoaming agent to 2 to 3 parts of water and mix evenly, then add hydroxypropyl methylcellulose aqueous solution, fractal structure silver particles and isopropanol in sequence to prepare the screen printing Fractal structure silver particle conductive ink.

Further, in step (1), stirring and mixing are performed at a stirring speed of 400-600 rpm.

Further, the preparation steps of the fractal structured silver particles specifically include: uniformly mixing the silver nitrate solution and the hydroxylamine solution at the same flow rate, separating the precipitate, washing and drying to obtain the fractal structured silver particles; wherein, the molar ratio of silver nitrate and hydroxylamine is 0.06 :0.24.

Further, the flow rates of the silver nitrate solution and the hydroxylamine solution are both 4-8 ml/min.

Compared with prior art, printing ink of the present invention has following beneficial technical effect:

The fractal structure silver particle used in the present invention is a special three-dimensional structure with both micrometer and nanometer dimensions. Because there are abundant contact points between adjacent silver particles, a uniform permeation network can be formed in the polymer matrix. In addition, the nanoscale tips of the fractal structure can be sintered at low temperature to save energy. The present invention uses fractal structure silver particles as conductive fillers, and cooperates with other raw materials to make inks. Due to its three-dimensional structural characteristics, it is easy to form a conductive network, thereby reducing the use of conductive fillers and reducing costs; at the same time, the amount of conductive fillers is small, effectively ensuring the material mechanical properties. Therefore, in the case of a certain content of fractal structure silver particles, the fractal structure silver particle conductive ink has the advantages of fast film-forming speed, good film-forming property, and excellent conductivity. The conductive paper made by using this conductive ink has a square resistance of 0.0818 ~0.6Ω.

The beneficial effects of the inventive method are as follows:

(1) The process of preparing conductive ink is simple to operate and low in cost;

(2) By adding fractal structure silver particles, a very good conductive network can be formed, with excellent conductivity; and the ink film-forming speed is fast and the film-forming property is good;

(3) The method of the present invention uses water as a solvent, which is simple, safe and environmentally friendly.

Further, the present invention prepares fractal structured silver particles with controllable and uniform morphology by controlling the molar ratio of silver nitrate solution and hydroxylamine solution when preparing fractal structured silver particles, and the solution flow rate during the preparation process. The fractal silver particles with dendrite structure are beneficial to improve the conductivity of the conductive ink.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments.

A fractal structure silver particle conductive ink for screen printing, comprising the following raw materials in parts by weight:

Among them, silver nitrate solution and hydroxylamine solution are used to synthesize silver particles with fractal structure, wherein the molar ratio of silver nitrate solution and hydroxylamine solution is 0.06:0.24, the pH value is 7, and the flow rates of the two solutions are the same, both 4-8ml/ min, mixed evenly, washed with ethanol and dried to obtain silver particles with fractal structure.

The viscosity of described hydroxypropyl methylcellulose is 2%, is used as dispersant and makes fractal structure silver microparticles disperse evenly in conductive ink and provides the dispersion stability of printing ink; The number average of Zonyl FC-300 fluorosurfactant The molecular weight is 1050, which can reduce the surface tension of water-based ink and promote the wettability of the substrate during printing; MO-2170 defoamer comes from BASF, which can well eliminate the foam generated during mechanical stirring. Zonyl FC-300 fluorosurfactant is preferably 0.002 to 0.006 parts, and MO-2170 defoamer is preferably 0.01 to 0.03 parts.

The particle size of the fractal structured silver particles is 5-15 μm.

A kind of preparation method of the fractal structure silver particle conductive ink of the present invention for screen printing, specifically comprises the following steps:

(1) First prepare the aqueous solution of hydroxypropyl cellulose, take 10-45 parts of hydroxypropyl methylcellulose, add 18-48 parts of distilled water, stir vigorously for half an hour, the stirring speed is preferably 400-600rpm, hydroxypropyl methylcellulose Cellulose is completely dissolved to obtain hydroxypropyl methylcellulose solution;

(2) Weigh 2 to 3 parts of water into the container according to the composition of the above fractal structure silver particle conductive ink, then add Zonyl FC-300 fluorosurfactant and MO-2170 defoamer, stir well until all components are mixed evenly ;

(3) In the state of stirring, add a certain amount of aqueous solution of hydroxypropyl methylcellulose and mix well; then add fractal structure silver particles and mix well; finally add isopropanol and stir well to obtain evenly dispersed fractal Structured Silver Microparticle Conductive Ink.

The invention provides a simple, low-cost fractal structure silver particle conductive ink with good conductivity and a preparation method thereof. The fractal structure silver particle conductive ink for screen printing obtained by using the above components can achieve the best effect. The film speed is fast, the film-forming property is good, and the advantages of excellent electrical conductivity.

Example 1:

(1) First prepare the aqueous solution of hydroxypropyl cellulose, take 10 parts of hydroxypropyl methylcellulose, add 18 parts of distilled water, stir vigorously for half an hour, the stirring speed is preferably 400rpm, and the hydroxypropyl methylcellulose is completely dissolved to obtain hydroxypropyl methylcellulose Propyl methyl cellulose solution;

(2) Weigh 2 parts of water into the container, then add 0.002 parts of Zonyl FC-300 fluorosurfactant and 0.01 part of MO-2170 defoamer, stir well until all components are mixed evenly;

(3) In the state of stirring, add the aqueous solution of hydroxypropyl methylcellulose and mix evenly; then add 2 parts of fractal structure silver particles and mix evenly; finally add 1 part of isopropanol and stir well to obtain a uniformly dispersed Fractal Structure Silver Particles Conductive Ink.

(4) The ink in step (3) is then printed on paper by screen printing, with a printing width of 2 mm and a thickness of 20 μm. After curing, a fractal structure silver particle conductive paper is obtained; the square resistance thereof is 0.0818Ω as measured by the four-point method.

The calculation formula of square resistance (R _S ) is: R _S ＝R _X ×F(D/S)×F(W/S)×F _SP where:

D——sample diameter (mm); S——average probe spacing (mm); W——test sample thickness (μm); F _SP ——probe spacing correction factor; F(D/S)—— Sample diameter correction factor; F(W/S)——sample thickness correction factor; R _X ——resistance value measured by low resistance tester (Ω)

Example 2:

(1) First prepare the aqueous solution of hydroxypropyl cellulose, take 30 parts of hydroxypropyl methylcellulose, add 30 parts of distilled water, stir vigorously for half an hour, the stirring speed is preferably 500rpm, and the hydroxypropyl methylcellulose is completely dissolved to obtain hydroxypropyl methylcellulose Propyl methyl cellulose solution;

(2) Weigh 2 parts of water into the container, then add 0.004 parts of Zonyl FC-300 fluorosurfactant and 0.02 parts of MO-2170 defoamer, stir well until all components are mixed evenly;

(3) In the state of stirring, add the aqueous solution of hydroxypropyl methylcellulose and mix evenly; then add 4 parts of fractal structure silver particles and mix evenly; finally add 4 parts of isopropanol and stir well to obtain a uniformly dispersed Fractal Structure Silver Particles Conductive Ink.

(4) The ink in step (3) is then printed on paper by screen printing, with a printing width of 2 mm and a thickness of 20 μm. After curing, a fractal silver particle conductive paper is obtained; the square resistance thereof is 0.6Ω as measured by the four-point method.

Example 3

(1) First prepare the aqueous solution of hydroxypropyl cellulose, take 45 parts of hydroxypropyl methylcellulose, add 40 parts of distilled water, stir vigorously for half an hour, the stirring speed is preferably 600rpm, and the hydroxypropyl methylcellulose is completely dissolved to obtain hydroxypropyl methylcellulose Propyl methyl cellulose solution;

(2) Weigh 2 parts of water into the container, then add 0.006 parts of Zonyl FC-300 fluorosurfactant and 0.03 parts of MO-2170 defoamer, stir well until all components are mixed evenly;

(3) In the state of stirring, add the aqueous solution of hydroxypropyl methylcellulose and mix evenly; then add 6 parts of fractal structure silver particles and mix evenly; finally add 6 parts of isopropanol and stir well to obtain a uniformly dispersed Fractal Structure Silver Particles Conductive Ink.

(4) The ink in step (3) is then printed on paper by screen printing, with a printing width of 3 mm and a thickness of 30 μm. After curing, a fractal structure silver particle conductive paper is obtained; the square resistance thereof is 0.1576Ω measured by the four-point method.

Example 4:

(1) First prepare the aqueous solution of hydroxypropyl cellulose, take 15 parts of hydroxypropyl methylcellulose, add 5 parts of distilled water, stir vigorously for half an hour, the stirring speed is preferably 400rpm, and the hydroxypropyl methylcellulose is completely dissolved to obtain hydroxypropyl methylcellulose Propyl methyl cellulose solution;

(2) Weigh 3 parts of water into the container, then add 0.006 parts of Zonyl FC-300 fluorosurfactant and 0.03 parts of MO-2170 defoamer, stir well until all components are mixed evenly;

(3) In the state of stirring, add the aqueous solution of hydroxypropyl methylcellulose and mix evenly; then add 4 parts of fractal structure silver particles and mix evenly; finally add 8 parts of isopropanol and stir well to obtain a uniformly dispersed Fractal Structure Silver Particles Conductive Ink.

(4) The ink in step (3) is then printed on paper by screen printing, with a printing width of 4 mm and a thickness of 30 μm. After curing, a fractal structure silver particle conductive paper was obtained; the square resistance was measured as 0.2147Ω by four-point method.

Example 5:

(1) First prepare the aqueous solution of hydroxypropyl cellulose, take 25 parts of hydroxypropyl methylcellulose, add 47.5 parts of distilled water, stir vigorously for half an hour, the stirring speed is preferably 500rpm, and the hydroxypropyl methylcellulose is completely dissolved to obtain hydroxypropyl methylcellulose Propyl methyl cellulose solution;

(2) Weigh 2.5 parts of water into the container, then add 0.002 parts of Zonyl FC-300 fluorosurfactant and 0.01 part of MO-2170 defoamer, stir well until all components are mixed evenly;

(3) In the state of stirring, add the aqueous solution of hydroxypropyl methylcellulose and mix well; then add 5 parts of fractal structure silver particles and mix well; finally add 10 parts of isopropanol and stir well to obtain a uniformly dispersed Fractal Structure Silver Particles Conductive Ink.

(4) The ink in step (3) is then printed on the paper by screen printing, with a printing width of 4 mm and a thickness of 40 μm. After curing, a fractal structured silver particle conductive paper was obtained; the square resistance thereof was measured to be 0.46Ω by the four-point method.

Comparative example 1:

(1) adopting the method identical with embodiment 1 to prepare the hydroxypropyl methylcellulose content is 0.5wt% hydroxypropyl methylcellulose solution;

(2) In the state of stirring, add the aqueous solution of 0.5wt% hydroxypropyl methylcellulose, mix well; then add 2 parts of fractal structure silver particles, mix well; finally add 2 parts of isopropanol, fully stir, A uniformly dispersed fractal structure silver particle conductive ink is prepared.

(3) The ink in step (2) is then printed on paper by screen printing, with a printing width of 2 mm and a thickness of 20 μm. After curing, a fractal structure silver particle conductive paper was obtained; the square resistance was 4.732Ω measured by the four-point method.

Comparative example 2:

(1) adopting the method identical with embodiment 1 to prepare and obtain the hydroxypropyl methylcellulose content is 1wt% hydroxypropyl methylcellulose solution;

(2) In the state of stirring, add the aqueous solution of 1wt% hydroxypropyl methylcellulose, mix uniformly; then add 4 parts of fractal structure silver microparticles, mix homogeneously; finally add 4 parts of isopropanol, fully stir, prepare A uniformly dispersed fractal structured silver particle conductive ink was obtained.

(3) The ink in step (2) is then printed on paper by screen printing, with a printing width of 2 mm and a thickness of 30 μm. After curing, a fractal structured silver particle conductive paper was obtained; the square resistance was 3.342Ω measured by the four-point method.

From Example 1 and Comparative Example 1 and Comparative Example 2, it can be seen that when no fluorosurfactant and defoamer are added, the square resistance of the conductive paper made by the conductive ink obtained is far greater than the square resistance of the conductive paper made by the conductive ink of the present application. . This is because the addition of fluorosurfactant can reduce the surface tension of water-based ink and promote the wettability of the substrate during printing, while the defoamer can well eliminate the foam generated during mechanical stirring, so that the prepared conductive ink has a good stability and printability.

The conductive ink prepared by the present invention is printed onto the paper, and the printing performance and mechanical properties of the printed electrode circuit are tested under various deformation conditions, including (a) release state; (b) bending state; (c) folding state and (d) kneading state.

(a) When the printed circuit is in a stable state, the LED emits light normally. (b) and (c) show that even under deformation conditions such as 180° bending and 90° folding, the printed circuit can still work normally, and the LED luminescence is not affected. (d) Even after strong random kneading, the LEDs in the printed circuit can still emit light normally, indicating that the printed circuit is firmly attached to the paper surface. The LED can emit light under bending deformation, folding deformation and curling deformation, indicating that the printed circuit has good electrical conductivity, flexibility and electrical stability under mechanical deformation.

The present invention illustrates the detailed method of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention can only be implemented depending on the above-mentioned detailed method. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (8)

1. a fractal structure silver particle conductive ink for screen printing, is characterized in that: In parts by weight, the raw materials include: 2. A conductive ink with fractal structure silver particles for screen printing according to claim 1, characterized in that: the particle size of the fractal structure silver particles is 5-15 μm. 3. a kind of fractal structure silver particle conductive ink for screen printing according to claim 1 is characterized in that: the fluorosurfactant adopts Zonyl FC-300 fluorosurfactant, and the defoamer model is BASF MO-2170 . 4 . A conductive ink with fractal structure silver particles for screen printing according to claim 1 , characterized in that: the fractal structure silver particles have a three-dimensional dendrite structure. 5. the preparation method of the fractal structure silver particle conductive ink of screen printing as any one of claim 1-4 is characterized in that: comprise the following steps: (1) first add hydroxypropyl methylcellulose to 18 to 48 parts of water and mix uniformly to obtain an aqueous solution of hydroxypropyl methylcellulose; (2) Add fluorosurfactant and antifoaming agent to 2 to 3 parts of water and mix evenly, then add hydroxypropyl methylcellulose aqueous solution, fractal structure silver particles and isopropanol in sequence to prepare the screen printing Fractal structure silver particle conductive ink. 6. The preparation method of the fractal structure silver particle conductive ink for screen printing according to claim 5, characterized in that: in step (1), stir and mix evenly at a stirring speed of 400-600 rpm. 7. the preparation method of the fractal structure silver particle conductive ink of screen printing according to claim 5 is characterized in that: the preparation step of fractal structure silver particle specifically comprises: silver nitrate solution and hydroxylamine solution are mixed uniformly by the same flow rate , separating the precipitate, washing and drying to obtain silver particles with a fractal structure; wherein, the molar ratio of silver nitrate and hydroxylamine is 0.06:0.24. 8. The preparation method of the fractal structure silver particle conductive ink for screen printing according to claim 7, characterized in that: the flow rates of the silver nitrate solution and the hydroxylamine solution are both 4-8ml/min.