JP7263771B2 - Coating agents, ejected materials and coating equipment - Google Patents

Description

The present invention relates to a coating agent, a discharge product, and a coating apparatus, and a coating agent used in technical fields that require a precise and uniform film thickness line pattern and stripe pattern, and a three-dimensional three-dimensional structure pattern in particular. It relates to a discharge and a coating device.

Conventionally, in order to form electrodes and circuits of electronic parts, electromagnetic wave shielding films, electromagnetic wave shielding materials, etc., conductive pastes in which metal fillers such as silver powder are dispersed in resin have been used (for example, patent documents 1, see Patent Document 2). Insulating pastes in which insulating fillers are dispersed are also used as electrodes and circuits of electronic parts, electromagnetic wave shielding films, electromagnetic wave shielding materials, and the like.
In recent years, as the density of electronic components has rapidly increased, the improvement of workability and cost reduction in mass production have become important issues. There is a strong demand for improving the conductivity of electrodes and the like formed from a coating material such as an insulating paste in which an insulating filler is dispersed. At the same time, there is also a demand for improving the thermal conductivity of the electrodes and the like in order to release heat generated when electricity is applied to the electrodes and the like.

However, if a metal filler such as silver powder is dispersed in the conductive paste at a high concentration in order to obtain a coating agent capable of improving such conductivity, the viscosity of the conductive paste increases and the coating workability decreases. . In addition, sedimentation of the metal filler causes non-uniformity of the conductive paste, which causes problems such as brittleness of electrodes and the like. In addition, the solvent that is added to reduce the viscosity of the conductive paste scatters when it is heated, causing voids. problems such as an increase in In a pattern formed by a method such as gravure printing, screen printing, flexographic printing, offset printing, or inkjet, for example, as shown in FIG. This often results in prints with a low ratio. Therefore, excellent conductive and thermally conductive pastes have been developed, but until now, printing with a high aspect ratio or printing with a three-dimensional structure has been difficult. Only a rough conductive film can be formed to form an electrode.

However, printing with a rectangular cross-sectional shape and a high aspect ratio is desired. For example, if the cross-sectional shape of the printed matter is rectangular and the aspect ratio is high, it becomes possible to form comb-shaped electrodes with a high aspect ratio as a lithium-ion battery, realizing a long-lasting lithium-ion battery with high output characteristics. is said to be possible. In addition, by forming wiring by printing with a rectangular cross-sectional shape and a high aspect ratio, dense wiring such as electronic circuits can be concentrated in a small area, and more current can flow through the wiring. Furthermore, the increased wiring surface area leads to improved thermal conductivity, and a heat dissipation effect can also be expected.

In printing materials, for example, in the development of power modules using silicon carbide, in order to reduce quality deterioration and environmental impact caused by differences in the coefficient of thermal expansion of ceramic substrates due to circuit formation at high temperatures close to 1000°C, Low-temperature sintering at 500°C or less is being demanded, and the development of low-temperature sintering type conductive materials that have a high aspect ratio of printed matter, maintain a three-dimensional structure close to a rectangle, and have excellent volume resistivity is required. . However, when the aspect ratio is increased, it is necessary to prepare the conductive material with a high-viscosity coating agent, and since printing with a high-viscosity coating agent is difficult, the viscosity must be low, and the printed shape collapses. There is a problem that

For example, a generally used screen printing method is considered as a printing method that requires a high aspect ratio for bus wiring for solar cell modules, finger wires, and the like. If bus wiring for a solar cell module, finger wires, and the like are printed by this screen printing method, the cross-sectional shape of the printed material 121 becomes semicircular as shown in FIG.
Especially when you want to print with a highly viscous coating agent of several thousand cp to several million cp, screen printing uses a plate with an opening width of several μm to 100 μm. It becomes difficult to eject the agent, and printing on the substrate is often impossible, and even if printing is possible, the yield is poor.

As a general countermeasure against such circumstances, a method of adding a solvent having a similar SP value (solubility parameter value at 25° C.) to lower the viscosity of the coating agent is adopted. ing. This countermeasure is not limited to screen printing, but is also applicable to printing methods such as gravure printing, screen printing, flexographic printing, offset printing, inkjet, coater head, and dispenser.
In terms of the physical properties of the coating material, which requires a high aspect ratio, the development of power modules using silicon carbide, etc. has reduced quality deterioration and environmental impact caused by differences in the coefficient of thermal expansion of ceramic substrates due to circuit formation at high temperatures near 1000°C. To reduce this, low-temperature sintering at 500°C or less is required.

Patent No. 6318137 JP 2018-070854 A

As described above, there is a demand for the development of a low-temperature sintering type conductive material that maintains a three-dimensional structure in which the printed matter has a high aspect ratio, has a nearly rectangular cross-sectional shape, and has an excellent volume resistivity. However, when the aspect ratio is increased, the conductive material must be made highly viscous. On the other hand, in order to improve the printability, it is necessary to add a solvent to lower the viscosity and increase the fluidity, and there is a trade-off relationship between them. In Patent Document 1, epoxy resin is used as the polymer, but epoxy resin is generally insoluble and has 2 to 5% residue even at 800°C. In addition, the epoxy resin has a complex crosslinked structure and the thermally decomposable organism is not as simple as the olefin polymer material. In printed matter, the coating agent made by dispersion with a simple polymer can be applied to the ejection port, intaglio plate, and stencil material of printing methods such as gravure, screen, metal mask, coater head, dispenser needle, etc. It sticks. Therefore, cohesive failure due to shearing occurs at the time of transfer from the ejection port, intaglio, or stencil to the substrate to be printed, resulting in the continuous formation of printed matter with a high aspect ratio and a three-dimensional structure close to a rectangle. is difficult.

In addition, a so-called hybrid coating agent has been developed in which a mixture of flaky silver powder and spherical silver powder is used to increase the chances of contact of the silver powder in the coating agent and improve electrical conductivity. In terms of the slipperiness of the coating agent on the walls of the ejection port and openings such as intaglios and stencils, the coating agent mixed with flake-like silver powder increases the friction against the wall surface and acts as a brake against ejection, which is a negative factor. I have to.
Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a low-temperature sintering type coating agent, a discharged material, and a coating device that are excellent in volume resistivity and thermal conductivity. .

In order to solve the above problems, as a result of extensive studies by the inventors of the present invention, it was found that materials to be added to coating agents used in printing methods such as gravure plates, screen plates, metal mask plates, coater heads, dispenser needles, etc. should be specified. was found to be suitable for improving physical properties such as ejection accuracy and volume resistivity.
According to one aspect of the present invention, a water-insoluble binder, a conductive metal, graphene and an inorganic substance as fillers, a water-insoluble dispersion medium , a water-insoluble solvent , and a water-insoluble solvent incompatible with the water-insoluble solvent and a water-soluble solvent, wherein the water-insoluble binder comprises an acrylic resin and a water-insoluble additive, and the water-insoluble additive is a polymer having an acrylic resin as a main chain with hydroxyl groups as functional groups. , or an elastomer obtained by cross-linking a polymer having a polyethylene glycol main chain with a hydroxyl group as a main chain with isocyanate, the conductive metal is spherical copper powder, the inorganic substance is silica powder or glass frit, and the A coating agent is provided in which the water-insoluble dispersion medium is a polyalkylene glycol derivative and the water-insoluble solvent is terpineol .

According to another aspect of the present invention, there is provided a discharge product obtained by discharging the coating agent of the above aspect onto a substrate, wherein the cross-sectional shape of the coating agent discharged onto the substrate is an arc with a radius of 10 μm or less. A jet having corners is provided.
According to another aspect of the present invention, the content of graphene in the amount of sintered material after sintering at 400° C. or higher and 900° C. or lower is 0.5° C., in the ejected material obtained by ejecting the coating agent of the above aspect. A discharge is provided that is 01% by mass or more and 5% by mass or less.
Furthermore, according to another aspect of the present invention, a discharge port is provided for discharging the coating agent of the above aspect onto an object to be coated, and a flow path communicating with the discharge port and supplying the coating agent to the discharge port. A coating device is provided in which at least portions of the outlet and the flow path that come into contact with the coating material are hydrophobic.

According to one aspect of the present invention, in a coater head and dispenser, a gravure plate, a screen plate, a metal mask plate, etc., the pattern shape is maintained, the aspect ratio is high, and the three-dimensional structure close to a rectangle is maintained to discharge (print ) can be performed, and a low-temperature sintering type coating agent having excellent volume resistivity, as well as an ejected material and a coating device can be provided.

It is a figure which shows the effect by the coating agent structure which concerns on one Embodiment of this invention. It is the image which observed the spherical silver powder used in one Embodiment of this invention. It is a figure applied by the conventional coating composition. It is a figure which shows the state which apply|coated the coating agent which concerns on one Embodiment of this invention. It is a figure which shows the shape which discharged the coating agent which concerns on one Embodiment of this invention on the board|substrate, and is an enlarged sectional view explaining a cross-sectional image and a principal part. It is a figure which shows the state which discharged the coating agent which concerns on one Embodiment of this invention on a board|substrate. It is the image which observed the cross section which discharged the coating agent which concerns on one Embodiment of this invention. It is a figure which shows the state which printed the coating agent which concerns on one Embodiment of this invention on the board|substrate. It is a figure which shows the state which printed the coating agent which concerns on one Embodiment of this invention on the board|substrate. It is a figure which shows the structure of the coating agent which concerns on one Embodiment of this invention. FIG. 2 shows a defect when simulating the silver mixture of the prior art document; It is an image which shows the cross-sectional structure of the conventional printed matter.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in each drawing described below, the same reference numerals are given to the parts that correspond to each other, and the description of overlapping parts will be omitted as appropriate. Further, the embodiment of the present invention exemplifies the configuration for embodying the technical idea of the present invention, and the material, shape, structure, arrangement, dimensions, etc. of each part are specified as follows. not a thing Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

<1> The coating agent according to one embodiment of the present invention includes a water-insoluble binder, a conductive metal, graphene and an inorganic substance as fillers, a water-insoluble dispersion medium, a water-insoluble additive, and a water-insoluble a solvent, and further contains a water-soluble solvent that is incompatible with the water-insoluble solvent.
<2> The water-insoluble binder is preferably a water-insoluble resin.
<3> 0.01 part or more and 5 parts or less of graphene and 5 parts or more of a water-insoluble binder when the mixture of the conductive metal excluding graphene among the fillers and the inorganic substance such as glass frit is 100 parts 7 parts or less, a water-insoluble mixture containing 0.01 parts or more and 50 parts or less of a three-part mixture of a water-insoluble dispersion medium, a water-insoluble additive, and a water-insoluble solvent, and 0.01 part of the coating agent and a water-soluble solvent of 50 parts or less.

<4> The polymer composition of the water-insoluble binder is a polymer having a main chain of an acrylic resin and an acrylic resin having a hydroxyl group as a functional group, or a polymer having a polyethylene glycol as a main chain having a hydroxyl group as a functional group, and is crosslinked with isocyanate. It is preferred that an elastomer is included. Unlike epoxy resin, acrylic resin is easy to decompose and completely decomposes at around 400° C. leaving no residue. The acrylic resin may be a composite resin of functional groups such as a hydroxyl group, an acrylic group, and a methacrylic group, and may be imparted with thermosetting and photocuring properties.

<5> The cross-sectional shape of the ejected matter (printed matter) ejected onto the base material using the coating agent according to one embodiment of the present invention has arcuate corners with a radius of 10 μm or less.
<6> The ejected matter (printed matter) ejected onto the substrate using the coating agent according to one embodiment of the present invention has a graphene content of the amount of the sintered material even after sintering at 400 ° C. or higher and 900 ° C. or lower. 0.01 mass % or more and 5 mass % or less remain.

<7> A coating device according to an embodiment of the present invention includes an ejection port for ejecting the coating agent, and a channel communicating with the ejection port and supplying the coating agent to the ejection port, wherein the ejection port and the channel Of these, at least the portion that comes into contact with the coating agent has hydrophobicity.
<8> Further, a coating apparatus according to another embodiment of the present invention includes an intaglio or stencil for discharging the coating agent onto an object to be coated, and the groove wall surface of the intaglio or stencil is hydrophobic. .

(coating agent)
The coating agent of the present embodiment is a conductive material, an insulating material, or the like, which is applied through a coater head and dispenser, a gravure plate, a screen plate, a hydrophobic ejection port formed in a metal mask plate, an intaglio plate, or a stencil. Multiple types of coating agents, such as conductive pastes composed of silver, carbon, copper powder, etc., insulating pastes, stretchable conductive inks developed with urethane materials, carbon elastomer materials, electrostatic elastomers, adhesives It is used as a coating agent when printing or coating a line pattern, a three-dimensional structure pattern, or a discontinuous pattern on the surface of a base material by ejecting or transferring coating agents such as agents and non-adhering agents while maintaining their shape. .

<Configuration>
The coating agent according to the present embodiment is a spherical filler that can print and transfer a three-dimensional structure shape close to a rectangle with a high aspect ratio by a printing method such as a gravure plate, a screen plate, a metal mask plate, a coater head, or a dispenser needle. In addition, it has a coating composition that utilizes the advantage of a thin layer of graphene that flexibly clings to it.
Components constituting the coating agent (coating composition) of the present embodiment include a water-insoluble binder (a polymer containing a water-insoluble dispersion medium), a filler (silver powder, copper powder, silica powder as an inorganic substance, graphene, organic powder etc.), water-insoluble dispersion media, water-soluble additives, water-insoluble solvents, and water-soluble solvents (organic solvents, water, etc.) incompatible with these water-insoluble solvents. Additives may be added to the coating agent of the present embodiment as necessary.

Here, the water-soluble solvent exhibits water-solubility contradictory to the water-insoluble dispersion medium for dispersing the binder, the water-insoluble additive, and the water-insoluble solvent. That is, in the coating agent of the present embodiment, a binder (polymer containing a dispersant) in which an inorganic filler or an organic filler (pigment) is dispersed, a solvent (organic solvent), and an additive are water-insoluble, and a water-soluble solvent is used. A prescribed amount is added and mixed.

Specifically, when the mixture of the conductive metal and the glass frit is 100 parts, the binder (polymer containing dispersant ) for dispersing a water-insoluble dispersion medium, a water-insoluble additive, and a water-insoluble solvent (corresponding to the ternary mixture and water-insoluble mixture described in the claims) , has a water-soluble additive solvent with a different polarity that does not destroy the physical properties of this coating material. Examples of the filler include silver powder, copper powder, silica powder, carbon (for example, graphene, carbon nanofiber), etc., which have been developed for fillers, printing applications, and the like. In addition, the coating agent of this embodiment is a coating agent for a coater head, a dispenser, a gravure plate, a screen plate, and a metal mask plate.

Generally, fillers, ink solvents and solvent compositions used in printing methods are solvent compositions containing a solvent and a compound represented by the following formula (1). In formula (1) below, R ¹ represents a monohydroxyalkyl group, and R ² represents a carboxyl group (C(=O)OH) or an amide group (C(=O)NH ₂ ).
R ¹ —CH ₂ —R ² (1)

[Purpose of composition]
As described above, the components constituting the coating agent of the present embodiment include a binder (a polymer containing a dispersant), a filler (silver powder, copper powder, silica powder, graphene, organic powder, etc.), a solvent (organic solvent, water etc.), additives, etc., and the above additive solvents (water-insoluble additive solvents, water-soluble additive solvents). The commonly used concept of Solubility Parameter (hereinafter referred to as SP value) assumes that the force acting between the solvent and solute is the intermolecular force, and the intermolecular force is used as a measure of the cohesive force. , two components with a small SP value difference are easily mixed (high solubility), and two components with a large SP value difference are difficult to mix (low solubility). That is, coating agents used in general printing applications are commercialized and used by mixing a binder (polymer), a solvent (organic solvent), and an additive with a small difference in SP value. Constituents of the coating agent according to the form are defined in a completely different way of thinking. In other words, in this embodiment, instead of examining the solubility parameter, a water-insoluble solvent and a water-insoluble solvent are used as the solvent and the solvent of the coating agent to be used, and an additive is added to it (that is, , a water-insoluble composition that uses a water-insoluble solvent and a water-insoluble solvent as a solvent and a water-insoluble solvent for the coating agent to be used, and further adds a water-insoluble additive) for the purpose of imparting a slipping effect The constituent components are defined with an emphasis on making the solvent to be kneaded water-soluble, which is the opposite.

<Additive solvent (non-water-soluble solvent)>
Examples of the additive solvent include n-heptane (SP value: 7.3), n-propanol (SP value: 11.8), 1,2,5,6-tetrahydrobenzyl alcohol (SP value: 11.3), Diethylene glycol ethyl ether (SP value: 10.9), 3-methoxybutanol (SP value: 10.9), triacetin (SP value: 10.2), propylene glycol monomethyl ether (SP value: 10.2), cyclopenta non (SP value: 10.0), γ-butyrolactone (SP value: 9.9), cyclohexanone (SP value: 9.9), propylene glycol-n-propyl ether (SP value: 9.8), propylene glycol -n-butyl ether (SP value: 9.7), dipropylene glycol methyl ether (SP value: 9.7), 1,4-butanediol diacetate (SP value: 9.6), 3-methoxybutyl acetate ( SP value: 8.7), propylene glycol diacetate (SP value: 9.6), ethyl lactate acetate (SP value: 9.6), ε-caprolactone (SP value: 9.6), 1,3-butylene Glycol diacetate (SP value: 9.5), dipropylene glycol-n-propyl ether (SP value: 9.5), 1,6-hexanediol diacetate (SP value: 9.5), dipropylene glycol- n-butyl ether (SP value: 9.4), tripropylene glycol methyl ether (SP value: 9.4), tripropylene glycol-n-butyl ether (SP value: 9.3), cyclohexanol acetate (SP value: 9 .2), diethylene glycol monoethyl ether acetate (SP value: 9.0), ethylene glycol methyl ether acetate (SP value: 9.0), diethylene glycol monobutyl ether acetate (SP value: 8.9), ethylene glycol monobutyl ether acetate (SP value: 8.9), methyl acetate (SP value: 8.8), ethyl acetate (SP value: 8.7), propylene glycol monomethyl ether acetate (SP value: 8.7), n-propyl acetate ( SP value: 8.7), dipropylene glycol methyl ether acetate (SP value: 8.7), water (SP value: 23.4), 3-methoxybutanol acetate (SP value: 8.7), butyl acetate ( SP value: 8.7), isopropyl acetate (SP value: 8.5), tetrahydrofuran (SP value: 8.3), dipropylene glycol methyl-n-butyl ether (SP value: 8.0), dipropylene glycol methyl -n-propyl ether (SP value: 8.0), dipropylene glycol dimethyl ether (SP value: 7.9), propylene glycol methyl-n-butyl ether (SP value: 7.8), propylene glycol methyl-n-propyl Ether (SP value: 7.8) and the like can be mentioned.

The dissolution parameter (SP value: Fedors' calculated value) at 25° C. of the additive solvent (water-insoluble solvent) mentioned here is only positioned as a reference for the solvent to be selected in this embodiment. The important thing is to determine that the dispersion medium and additive solvent for dispersing the binder (polymer containing the dispersant) and the solvent are water-insoluble, and add a water-soluble liquid that is the exact opposite of this dispersion medium and solvent. It is added as a solvent (water-soluble solvent).

[Water-insoluble and water-soluble]
Definitions of water-insoluble and water-soluble are the definitions of water-soluble liquids of Class 4 dangerous goods. Class 4 dangerous goods are flammable liquids. They are further divided into (1) those that dissolve in water (water-soluble) and (2) those that do not dissolve in water (water-insoluble). Under the ordinance, it is defined as follows.
The water-soluble liquid maintains a uniform appearance when mixed with the same volume of pure water at 1 atmosphere and 20°C. It separates into two layers when mixed. If the specific gravity of the liquid is less than that of water, a non-aqueous layer will form above the water layer, and if the specific gravity of the liquid is greater than that of water, below the water layer. In the case of water-soluble liquids, the mixture becomes uniform without layer separation. Some substances, such as diethyl ether, which is a special flammable substance, and ethyl acetate, which is a class 1 petroleum, are slightly soluble in water, but by definition they are classified as water-insoluble.
Therefore, the additive solvent can be classified as follows based on the definitions of water-insoluble and water-soluble.

[Water-soluble additive solvent (water-soluble solvent)]
Water-soluble additive solvents (water-soluble solvents) include n-propanol (SP value: 11.8), 1,2,5,6-tetrahydrobenzyl alcohol (SP value: 11.3), diethylene glycol ethyl ether (SP value : 10.9), 3-methoxybutanol (SP value: 10.9), propylene glycol monomethyl ether (SP value: 10.2), γ-butyrolactone (SP value: 9.9), propylene glycol-n-propyl Ether (SP value: 9.8), dipropylene glycol methyl ether (SP value: 9.7), ethyl lactate acetate (SP value: 9.6), ε-caprolactone (SP value: 9.6), tripropylene Glycol methyl ether (SP value: 9.4), tripropylene glycol-n-butyl ether (SP value: 9.3), diethylene glycol monoethyl ether acetate (SP value: 9.0), ethylene glycol methyl ether acetate (SP value : 9.0), tetrahydrofuran (SP value: 8.3), dipropylene glycol methyl-n-butyl ether (SP value: 8.0), dipropylene glycol methyl-n-propyl ether (SP value: 8.0) , dipropylene glycol dimethyl ether (SP value: 7.9), propylene glycol methyl-n-propyl ether (SP value: 7.8), water (SP value: 23.4), and the like.

[Water-insoluble additive solvent (water-insoluble solvent)]
Non-water-soluble additive solvents (non-water-soluble solvents) include triacetin (SP value: 10.2), cyclopentanone (SP value: 10.0), cyclohexanone (SP value: 9.9), propylene glycol-n. -Butyl ether (SP value: 9.7), 1,4-butanediol diacetate (SP value: 9.6), 3-methoxybutyl acetate (SP value: 8.7), propylene glycol diacetate (SP value: 9.6), 1,3-butylene glycol diacetate (SP value: 9.5), dipropylene glycol-n-propyl ether (SP value: 9.5), 1,6-hexanediol diacetate (SP value : 9.5), dipropylene glycol-n-butyl ether (SP value: 9.4), cyclohexanol acetate (SP value: 9.2), diethylene glycol monobutyl ether acetate (SP value: 8.9), ethylene glycol mono Butyl ether acetate (SP value: 8.9), methyl acetate (SP value: 8.8), ethyl acetate (SP value: 8.7), propylene glycol monomethyl ether acetate (SP value: 8.7), n-propyl Acetate (SP value: 8.7), dipropylene glycol methyl ether acetate (SP value: 8.7), 3-methoxybutanol acetate (SP value: 8.7), butyl acetate (SP value: 8.7), isopropyl acetate (SP value: 8.5), propylene glycol methyl-n-butyl ether (SP value: 7.8), and the like.

[Addition amount of additive solvent]
As for the amount of the additive solvent, 0.01 part or more and 5 parts or less of graphene was added to 100 parts of the mixture of the conductive metal and the glass frit by kneading the water-soluble additive solvent (water-soluble solvent). A water-insoluble dispersion medium and a water-insoluble solvent for dispersing a binder (polymer containing a dispersant) containing a filler, depending on the situation, dispersed in the gap between the filler and the polymer formed by the water-insoluble additive. The amount of water-soluble additive solvent (water-soluble solvent) used will be absorbed. Therefore, the absorbed amount varies depending on the filler, water-insoluble dispersion medium, water-insoluble solvent, molecular weight, cross-linking density and content ratio of the water-insoluble additive. In other words, 0.01% or more and 50% or less of the total mass before kneading with the additive solvent is desirable.
If the amount of additive solvent exceeds the amount determined by the amount absorbed by the additive solvent, the organic matter, which is an insulating material, enters between the conductive fillers too much, destroying the linkage between the conductive fillers, etc. Desired physical properties such as modulus are lost. In the case of graphene too, if it becomes too much, the cost will increase and the binder effect of the polymer will be lost.

The configuration of the coating agent of the present embodiment takes, as an example of a concept, a mixture of rubber or elastomer (polymer) and oil (solvent). Rubber or elastomers swell. This is a phenomenon in which oil enters between the molecules of rubber or elastomer. If the oil mixes easily with the rubber, it swells. In other words, when the main solvent of the coating material is non-water-soluble, by adding a water-soluble additive solvent (water-soluble solvent), substances with different polarities, here the non-water-soluble solvent and the water-soluble solvent, mix with each other. Therefore, it is considered that the following phenomenon occurs when the structure becomes like a sponge and pressure is applied from the outside.
The water-soluble solvent oozes out onto the surface of the non-water-soluble solvent coating material such as a binder containing a filler (polymer containing a dispersant), and wets the walls of the openings of the ejection port and the intaglio, stencil, etc., forming a thin film. As a result, the non-water-soluble solvent floats on the film formed by the water-soluble solvent.

As shown in FIG. 1, a coating agent having the above characteristics is applied to a water-soluble solvent through a hydrophobic ejection port 11 formed in a coater head, a dispenser, a gravure plate, a screen plate, a metal mask plate, an intaglio plate, or a stencil plate. 12 forms a thin film 13 at the interface between the coating agent and the hydrophobic ejection port 11, or the surface of the intaglio or stencil, and is given slipperiness. 11, intaglio, or stencil, can be printed or coated on the substrate as it is. In addition, it is preferable that at least a portion of the ejection port 11 and the flow path communicating with the ejection port 11, which is in contact with the coating agent, be hydrophobic. Further, when printing is performed using an intaglio or a stencil, it is preferable that the groove walls of the intaglio or the stencil have hydrophobic properties.
Thus, for example, an ejected matter (printed matter) formed by ejecting a coating agent from a rectangular hydrophobic ejection port can form a pattern with a rectangular cross-sectional shape. It can be calculated from the horizontal dimension or (upper base + lower base) x height/2. That is, it is possible to form a pattern exhibiting a non-destructive and stable electrical resistance value.

The configuration of the coating agent of the present embodiment is characterized in that the coating agent contains graphene.
As mentioned above, there is a demand for the development of a low-temperature sintering type conductive material that has a high aspect ratio of printed matter, maintains a nearly rectangular three-dimensional structure, and has excellent volume resistivity. , the conductive material must be highly viscous. However, in order to improve the printability, there is a trade-off relationship such that a solvent is added to lower the viscosity and increase the fluidity.
By containing graphene, the coating agent of the present embodiment has a high aspect ratio of printed matter, maintains a three-dimensional structure close to a rectangle, and can reduce volume resistivity. Low-temperature sintering pattern with excellent volume resistivity. can be formed.
In the present embodiment, when spherical silver powder is selected as the conductive filler, the graphene-added coating agent is dry-dispersed by adding 1% by mass or more and 5% by mass or less of graphene to the spherical silver powder and the glass frit. After that, according to the embodiment of the present invention, a water-insoluble binder (a polymer containing a dispersant), a water-insoluble solvent, and a water-insoluble solvent are dispersed, and 1% by mass or more and 50% by mass of a water-soluble solvent are added. do.

The binder is preferably a water-insoluble resin, for example, an acrylic resin that is water-insoluble and has a decomposition completion temperature of around 400° C. in the atmosphere. It is desirable to use a high-boiling organic solvent such as terpineol as the water-insoluble solvent. As for the dispersant, a water-insoluble one having a decomposition completion temperature of 400° C. or less in the atmosphere is desirable. In some cases, polymers with polyethylene glycol as a main chain as water-insoluble additives or polymers such as acrylic resins are crosslinked by radical polymerization, graft polymerization, block polymerization, matrix polymerization, especially polymerization with urethane bonds, etc. By using, a mixture containing a water-insoluble dispersion medium, a water-insoluble solvent and a water-insoluble additive for dispersing the binder (polymer) (a ternary mixture and a water-insoluble mixture described in the claims ) is configured, it is possible to adjust the absorption amount of the water-soluble solvent dispersed in the gap between the polymer and the filler.
The acrylic resin may be a composite resin of functional groups such as a hydroxyl group, an acrylic group, and a methacrylic group, and may be imparted with thermosetting and photocuring properties.

In the present embodiment, the coating agent to which graphene is added is characterized in that the shape of the printed matter formed by the addition of graphene and the printed matter sintered at around 400 ° C. can be maintained. Carbon, which has the same composition as graphene carbonized by decomposition and combustion, burns off almost 100% at around 600 ° C according to thermogravimetric and differential thermal analysis. It remains without burning, and since 40% by weight of the single unit remains without burning even around 800°C, the shape of the sintered printed material can be maintained even in the range of 400°C to 900°C.

(Example 1)
99 parts of the spherical silver powder 21 ^shown in FIG ^. D50 8.0 μm) and 1 part of graphene (Gi-PW-F031 manufactured by Angstoron Materials, particle size distribution 4 μm or more and 12 μm or less, thickness 10 nm or more and 20 nm or less, ratio surface area>15 m ² /g) and 1 part, 3 parts, and 5 parts of this graphene, respectively, were mixed with 12 parts of terpineol (hazardous material class 4, 3 stones, water-insoluble), and a water-insoluble dispersion medium. 4 parts of acrylic binder (water-insoluble) and 7 parts of acrylic binder (water-insoluble) were dispersed with a planetary stirrer, and then 5 parts of water-soluble solvent were added to prepare pastes.

Mixed frits such as bismuth (III) oxide, boron oxide, tellurium dioxide, and vanadium pentoxide were used as the glass frit. The dispersant has a complete decomposition temperature of 400° C. or lower in the atmosphere.
In addition, the acrylic binder is composed of 4 parts of an acrylic resin with a complete decomposition temperature of 400°C in the atmosphere (complete decomposition temperature of 350°C <atmosphere>, 410°C <under nitrogen>), and a polyethylene glycol main chain with hydroxyl groups as functional groups. 3 parts of an elastomer (water-insoluble additive) obtained by cross-linking a polymer obtained by crosslinking with an isocyanate having two or more isocyanate groups such as hexamethylene diisocyanate was used.

The composition of the above acrylic binder is composed of an acrylic resin with a complete decomposition temperature of 400°C or less in the atmosphere (complete decomposition temperature of 350°C <atmosphere>, 410°C <under nitrogen>) and polyethylene glycol with hydroxyl groups as functional groups as the main chain. An elastomer obtained by cross-linking a polymer obtained by crosslinking with an isocyanate having two or more isocyanate groups such as hexamethylene diisocyanate was used.
In Example 1, out of 7 parts of the acrylic binder (water-insoluble), 4 parts of the former (acrylic resin) and 3 parts of the latter (elastomer crosslinked with isocyanate) were used. rice field. Depending on the situation, the composition of both may be adjusted within the range of 1 to 7 copies. In the latter case, an elastomer obtained by cross-linking an acrylic resin having hydroxyl groups with isocyanate at a complete decomposition temperature of 400° C. or less may be used.

Next, the paste prepared under the above conditions was applied on a polyimide film in a size of 1 cm×1 cm square, and sintered in an oven at 400° C. for 1 hour.
As a result, as shown in FIG. 3, the coating pattern 31 of 1 cm×1 cm square to which no graphene was added had cracks 32 and peeling from the coated base material, and the volume resistivity was 3.22×10 ⁻³ . Ω·cm. Application pattern 41 in which 1 part of graphene was added in FIG. 4 did not crack. ^A coating pattern 42 with a volume resistivity of 4.51×10 ⁻⁵ Ω·cm and 3 parts of graphene does not crack. The pattern 43 had no cracks and had a volume resistivity of 5.34×10 ⁻⁵ Ω·cm. By the way, volume resistivity is an index that indicates how easily electricity flows in conductive materials such as metal wiring and metal foil. evaluation.

From Example 1, it can be seen that if graphene is not added, the connection between the fillers is lost, and the adhesive strength between the fillers and between the substrates due to melting of the glass frit is significantly reduced. Therefore, by increasing the proportion of glass frit, which is also an insulator, and increasing the adhesive strength after sintering at 400°C, the printed shape is maintained. do. That is, a trade-off relationship holds. However, when at least 1 to 5 parts of graphene was added, the adhesive strength and volume resistivity after sintering at 400° C. could be maintained without increasing the ratio of the insulating glass frit.
It was also found that the color of the surface also changed depending on the amount of graphene added. As shown in FIG. 4, the surface of the coating pattern 41 with 1 part was brown, the coating pattern 42 with 3 parts was light brown, and the coating pattern 43 with 5 parts was still silver. Although there was not much effect on the volume resistivity, the result was that it was also effective in judging superiority in appearance.

Further, as shown in FIG. 5, a cross-sectional shape 51 of printed matter or ejected matter applied onto a base material from a coater head, dispenser, gravure plate, screen plate, or metal mask plate using the paste according to the present invention has a radius of It has an arc-shaped corner portion 52 of 10 μm or less. By having a radius of 10 μm or less, effects such as improved adhesion to the substrate, improved printing stability, and increased flat area on the top of the printed matter can increase the bonding area with other devices and improve electrical conductivity. is obtained. This printed matter or ejected matter includes a non-water-soluble binder in which graphene and a filler are dispersed, a non-water-soluble dispersion medium and a non-water-soluble additive for dispersing the binder, and a water-soluble additive solvent that contradicts the non-water-soluble solvent. and

(Example 2)
Since the addition of graphene in Example 1 improved the adhesion between fillers and substrates, 99 parts of spherical copper powder (particle size distribution D50 1.08 μm) and 1 part of glass frit (particle size distribution D50 8.0 μm) and 100 parts of the mixed powder dispersed in a mortar, 3 parts of graphene was added, 12 parts of terpineol (hazardous material Class 4 3 stone non-water-soluble), 4 parts of water-insoluble dispersion medium , acrylic binder ( Water-insoluble) was dispersed with a planetary stirrer at a rate of 7 parts, and then 5 parts of a water-soluble solvent was added to obtain a paste. Using this paste, from a discharge head with 500 μm × 500 μm square discharge ports arranged horizontally at a pitch of 1 mm, using a Mono-type dispenser, the tank pressure was 500 kPa, the gap between the base material and the head was 0 mm, and the discharge amount was 0.09 ml. /s and a drawing speed of 60 mm/s. Normally, lines having a semicircular cross-sectional shape are discharged, but in Example 2, seven sharp rectangular lines 61 were discharged as shown in FIG. As a result of sintering this discharge at 400° C. in a nitrogen atmosphere, a good result of volume resistivity of 8.50×10 −5 Ω·cm 3 was obtained. Graphene 71 (FIG. 7) is the numerous black dots in the cross section of line 61 shown in FIG.

(Example 3)
In Example 1, it was confirmed that the introduction of graphene improved the adhesion between fillers and substrates. Therefore, when 99 parts of spherical silver powder (particle size distribution D50: 1.08 μm) and 1 part of glass frit (particle size distribution: D50: 8.0 μm) are dispersed in a mortar to make 100 parts of mixed powder, 3 parts of graphene is added to obtain terpineol. After dispersing 12 parts of (hazardous material Class 4 3 non-water-soluble), 4 parts of non-water-soluble dispersion medium , and 7 parts of acrylic binder (non-water-soluble) with a planetary stirrer, add 5 parts of water-soluble solvent. A paste was prepared. Using this paste, stencil printing was performed with a metal mask having a line width of 200 μm and a film thickness of 150 μm, a squeegee rubber hardness of 70 degrees, an attack angle of 70 degrees, a clearance of 200 μm, and a printing speed of 50 mm/s.

As a result, as shown in FIG. 8, a sharp rectangular high aspect ratio print 81 having a line width of 200 μm and a height of 90.88 μm was obtained. A modulus of 9.0×10 ⁻⁵ Ω·cm was obtained.
As shown in FIG. 9(a), a normal metal mask 91 is mainly produced by zero-gap printing. On the other hand, as shown in FIG. 9B, by providing a high clearance 94, the adhesion of the paste 92 to the base material 95 due to pressing of the squeegee during printing and the rigidity of the metal mask 91 after printing are reduced. Due to the shear 93 in the direction perpendicular to the surface of the base material 95 to which the paste 92 is attached, slipperiness occurs at the interface between the metal mask 91 and the paste 92 according to this embodiment, and the adhesive force between the fillers due to graphene, Due to the synergistic effect of the adhesive strength with the substrate, we were able to obtain a rectangular print that stood up vertically while maintaining its shape.

(Example 4)
In Example 1, it was confirmed that the introduction of graphene improved the adhesion between fillers and substrates. Therefore, 99 parts of spherical copper powder (particle size distribution D50: 2.7 μm, specific surface area: 0.36 m ² /g, tap density: 4.8 g/cm ² ) and 1 part of glass frit (particle size distribution: D50: 8.0 μm) were dispersed in a mortar. When the mixed powder is 100 parts, 3 parts of graphene is added, 12 parts of terpineol (dangerous material Class 4 3 stone non-water-soluble), 4 parts of non-water-soluble dispersion medium , 7 parts of acrylic binder (non-water-soluble) A paste was prepared by adding 5 parts of a water-soluble solvent after dispersing with a planetary stirrer at a rate of 1 part. Using this paste, from a discharge head with 500 μm × 500 μm square discharge ports arranged horizontally at a pitch of 1 mm, using a Mono-type dispenser, the tank pressure was 500 kPa, the gap between the base material and the head was 0 mm, and the discharge amount was 0.09 ml. /s and a drawing speed of 60 mm/s.

Normally, lines having a semicircular cross-sectional shape are discharged, but in this embodiment, as shown in FIG. 6, seven sharp rectangular lines 61 are discharged. As a result of sintering this ejected product at 400° C. in a nitrogen atmosphere, a result of volume resistivity of 5.04×10 ⁻⁵ Ω·cm was shown. When observing the cross section of this line 61, it was observed that graphene 71 was scattered as shown in FIG. According to the measurement by a thermogravimetric differential thermal analyzer (TG-DTA), the decomposition temperature of graphene is around 530 ° C., which is the 1.0% weight loss start temperature. Nearly 100% mass remains. Therefore, since the volume resistivity of graphene is about 10 ⁻⁶ Ω·cm, the link effect between fillers such as graphene 101 shown in the composition diagram of the coating agent in FIG. 10 is maintained even after sintering at 400° C. You can think of it. 102 in FIG. 10 indicates spherical copper powder. FIG. 10 shows the configuration of the coating agent when the spherical copper powder is used as the filler (in the cases of Examples 2 and 4). As in Examples 1 and 3, when spherical silver powder is used as the filler, the composition of the coating agent is the same as that shown in FIG.

(Comparative example 1)
Spherical silver powder (SPQ05S Mitsui Mining & Smelting Co., Ltd., specific surface area 1.00 m ² /g, tap density 5.00 g/cm ² , particle size distribution D50 1.08 μm) 21 (Fig. 2) and flaky silver powder (SF-KS Mitsui Metal Mining Co., Ltd., specific surface area 1.75 m ² /g, tap density 3.33 g / cm ² , particle size distribution D50 2.41 μm) is 50% for both, 99 parts of mixed powder with a total of 100% and glass frit (particle size distribution D50 8.0 μm) 1 part is dry-dispersed in a mortar or the like to 100 parts, graphene (Gi-PW-F031 manufactured by Angstoron Materials, particle size distribution 4 μm or more and 12 μm or less, thickness 10 nm or more and 20 nm or less, specific surface area >15 m ² /g) and graphene added with 1 part, 3 parts and 5 parts, respectively, 12 parts of terpineol (Hazardous material class 4 3 stone non-water-soluble), 4 parts of non-aqueous dispersion medium , After dispersing 7 parts of an acrylic binder (insoluble in water) with a planetary stirrer, a paste was prepared by adding 5 parts of a water-soluble solvent. This paste was applied using a Mohno-type dispenser (Mohno Master V1 manufactured by Musashi Engineering) under the conditions of a tank pressure of 500 kPa, a gap between the base material and the head of 0 mm, a discharge amount of 0.09 ml/s, and a drawing speed of 60 mm/s. It was discharged onto a polyimide film.

Seven sharp rectangular lines were ejected in Examples 1 to 4, except when the graphene of Example 1 was not mixed (in the case of "1" in Example 1 in Table 1 below). However, under the conditions of Comparative Example 1, as shown in FIG. 11, the slipperiness of the coating material 111 became non-uniform between the lines, and an intermittent torn pattern was formed. It is considered that the spherical silver powder alone has a smooth grain shape and thus has little resistance to the ejection port, but the inclusion of the flaky silver powder increases the risk of resistance at the ejection port, making uniform ejection impossible.
In other words, the flaky silver powder is a negative factor for the lubricious coating agent according to the present embodiment.
From this result, since the graphene 101 (Fig. 10) has a single-layer plate-like structure like a robe of feathers, individual spherical silver powder and spherical copper powder links are formed to act as a dispersant and a binder. After sintering, a gauze-like permeation layer containing molten glass frit was formed, and it can be considered that the printing effect of the three-dimensional structure as in the above example was obtained.

Table 1 shows the evaluation results of various characteristics in Examples 1 to 4 and Comparative Example 1. In addition, in Table 1, the shape of the line applied on the substrate was determined as the print shape. Regarding Comparative Example 1, the one to which 3 parts of graphene was added was described as a representative. Regarding the print shape in Table 1, if the cross-sectional shape is not a semicircular shape but a sharp rectangle as shown in FIG. Those with an obtuse angle and no breakage of the line were judged to be "Δ (second point)", and those with a semicircular cross-sectional shape or breakage of the line were judged to be "X (improper)".

In addition, in Table 1, the viscosity was measured using an E-type viscometer (HBDV-II manufactured by BROOKFIELD), using a cone spindle CCPA-52Z, and a shear rate in the range of 0.02 to 25 (/ s). The approximate viscosity (Cp) shown at 1 (/s) was used.
Here, the viscosity range in which the rectangular cross-sectional shape can be maintained is from 100,000 Cp to 400,000 Cp, and the viscosity should be as high as possible to maintain the shape. A volume resistivity value of 10 ⁻⁵ Ω·cm is generally regarded as good for a circuit formed of a conductive paste.

From the above, the case where graphene was added in Example 1, in which the print shape was determined to be "△" or "○", and Examples 2 to 4 have good characteristics in terms of viscosity and volume resistivity. I was able to confirm that. Moreover, it was confirmed that even a high-viscosity paste with a viscosity of 400,000 Cp, which cannot be printed normally, can be printed with a favorable cross-sectional shape.
In addition, as shown in Table 1, among the examples in which good printing was possible, the maximum amount of graphene added was 5 parts, so the amount of sintered material after all the added organic matter was decomposed It can be seen that effective physical properties can be obtained within the range of 0.01% by mass or more and 5% by mass or less as a weight ratio of the graphene as a filler.

As described above, according to one aspect of the present invention, the following effects are obtained.
(a) Since a rectangular pattern can be formed, if it is formed with conductive ink, the cross-sectional area can be calculated from the vertical x horizontal dimensions or (upper base + lower base) x height ÷ 2. It is possible to form a conductive wire that is destructive and exhibits a stable electrical resistance value.
(b) By using the coating agent according to the above embodiment, it is possible to obtain a printed matter or ejected matter having a shape close to the shape of the ejection port or plate pattern opening. ) can be formed.
(c) Since a steep surface can be formed perpendicularly to the base material, in the case of line ejection, for example, a structure can be produced in which the gaps between rectangular lines are minimized.
(d) Rectangular patterns with a high aspect ratio (height/base) can be formed, and narrow widths allow more lines to be formed.

(e) By adding graphene, it is possible to sinter at a low temperature of 500°C or less in order to reduce the quality deterioration and environmental load caused by the difference in the thermal expansion coefficient of the ceramic substrate due to the circuit formation at a high temperature of nearly 1000°C, and the aspect of the printed matter. It is possible to form a ceramic substrate circuit using a low-temperature sintering type conductive material that has a high ratio, maintains a nearly rectangular three-dimensional structure, and has an excellent volume resistivity.
In other words, there is a possibility of application in the fields of electronics, high-performance films, security, and the like, and it is possible to form structures that cannot be formed by photolithography or nanoimprinting.
(f) As a synergistic effect of the above effects, it is possible to "form a conductive material with a high aspect ratio" of the printed matter, that is, increase the surface area as a result, and form a heat sink structure with high thermal conductivity.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and the present invention includes any modifications that do not depart from the gist of the present invention.

In the present invention, it is possible to sinter at a low temperature of 500 ° C or less a nearly rectangular three-dimensional structure pattern that could not be printed so far. Due to the strain stress generated at the interface due to the difference in thermal expansion coefficient, there are merits such as avoiding the risk of peeling of the printed circuit, and the ability to use other materials that are not exposed to high temperatures. is expected to reduce environmental impact. Therefore, in fields where circuit formation on ceramic substrates and three-dimensional patterns are required, for example, resistors, capacitors and other small electronic parts, color filters for liquid crystal display elements (LCDs), fuels, etc. It exhibits many effects, such as the ability to easily manufacture structures such as battery electrodes, all-solid battery electrodes, solar cells, and sensors with high quality and low cost. In addition, although the silver filler is used as an example this time, the same configuration can be applied to a conductive paste composed of, for example, aluminum, carbon, copper powder, or the like. It can be used for plates with hydrophobic ejection ports and patterned surfaces that have a large contact angle, which is an index of wettability.

Reference Signs List 11: Discharge port 12: Water-soluble solvent 13: Film 21: Spherical silver powder 31: Coating pattern without added graphene 32: Cracks 41: Coating pattern with 1 part of graphene added 42: Coating pattern with 3 parts of graphene added: 43: Graphene Application pattern 51 Cross-sectional shape 52 Corner 61 Sharp rectangular line 71 Graphene 81 High aspect ratio printing 91 Metal mask 92 Paste 93 Shear 94 Clearance 95 Base Material 101...Graphene 102...Silver powder 111...Coating agent 121...Printed matter

Claims (7)

a water-insoluble binder;
Conductive metals, graphene and inorganics as fillers;
a non-aqueous dispersion medium;
a water - insoluble solvent ;
and a water-soluble solvent that is incompatible with the water - insoluble solvent,
The water-insoluble binder contains an acrylic resin and a water-insoluble additive, and the water-insoluble additive is a polymer having an acrylic resin as a main chain with hydroxyl groups as functional groups, or a polymer having hydroxyl groups as functional groups. It is an elastomer obtained by cross-linking a polymer having a polyethylene glycol main chain with isocyanate,
The conductive metal is spherical copper powder,
The inorganic substance is silica powder or glass frit,
The non-aqueous dispersion medium is a polyalkylene glycol derivative,
A coating agent , wherein the water-insoluble solvent is terpineol . 2. The coating agent according to claim 1, wherein the water-insoluble binder is a water-insoluble resin. When the mixture of the conductive metal and the inorganic substance in the filler is 100 parts,
0.01 parts or more and 5 parts or less of the graphene,
5 parts or more and 7 parts or less of the water-insoluble binder;
a water-insoluble mixture containing 0.01 parts or more and 50 parts or less of a three-part mixture of the water-insoluble dispersion medium, the water-insoluble additive, and the water-insoluble solvent;
3. The coating agent according to claim 1, further comprising 0.01 part or more and 50 parts or less of the water-soluble solvent. A discharge product obtained by discharging the coating agent according to any one of claims 1 to 3 onto a substrate,
A discharge material, wherein the cross-sectional shape of the coating agent discharged onto the base material has an arcuate corner with a radius of 10 μm or less. A discharge material obtained by discharging the coating agent according to any one of claims 1 to 3 , wherein the content of graphene in the amount of sintered material after sintering at 400 ° C. or higher and 900 ° C. or lower is 0.5. 01% by mass or more and 5% by mass or less. A discharge port that discharges the coating agent according to any one of claims 1 to 3 onto an object to be coated, and a flow path that communicates with the discharge port and supplies the coating agent to the discharge port. prepared,
A coating apparatus according to claim 1, wherein at least a portion of said ejection port and said channel that contacts said coating agent is hydrophobic. A coating comprising an intaglio or stencil for printing the coating agent according to any one of claims 1 to 3 on an object to be coated, wherein the groove wall surface of the intaglio or stencil is hydrophobic. Device.

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