TWI698474B - Conductive composition - Google Patents

Abstract

The present invention provides a conductive composition with excellent durability and conductivity and low cost, and a conductive paste containing the conductive composition.

The conductive composition of the present invention contains flake metal powder, salicylic acid compound and o-aminophenol, and the content of the salicylic acid compound is 0.04 parts by weight to 1.6 parts by weight relative to 100 parts by weight of the flake metal powder Parts, relative to 100 parts by weight of the flake metal powder, the content of o-aminophenol is 1.2 parts by weight to 4.5 parts by weight.

Description

Conductive composition Invention field

The present invention relates to a conductive composition.

Background of the invention

In the past, regarding a conductive paste composed of resin and metal powder, a method of treating metal powder with fatty acid has been known. For example, Patent Document 1 discloses a method of coating the surface of flake copper powder with fatty acid as an antioxidant, thereby improving the durability of the flake copper powder. However, if the surface of the copper powder is coated with an antioxidant, the contact resistance between the copper powders will increase, and there will be a problem that the performance as a conductive paste cannot be fully exhibited. On the other hand, if the coating amount of the antioxidant is reduced, there will be a problem that sufficient durability cannot be obtained.

In addition, in order to improve the durability of the copper powder itself, a method of coating the copper powder with silver is known. However, this method has a problem that the cost will increase.

Advanced technical literature Patent literature

Patent Document 1: Japanese Patent Application Publication No. 11-264001

Summary of the invention

The present invention was completed in order to solve the above-mentioned conventional problems, and its object is to provide a conductive composition having excellent durability and conductivity and low cost, and a conductive paste containing the conductive composition.

The conductive composition of the present invention includes flake metal powder, salicylic acid compound and o-aminophenol, and relative to 100 parts by weight of the flake metal powder, the content of the salicylic acid compound is 0.04 parts by weight to 1.6 Parts by weight, relative to 100 parts by weight of the flake metal powder, the content of the o-aminophenol is 1.2 parts by weight to 4.5 parts by weight.

In one aspect, flake copper powder is contained as the flake metal powder.

In one aspect, salicylic acid is contained as the above-mentioned salicylic acid compound.

Another object of the present invention provides a conductive paste. This conductive paste contains the above-mentioned conductive composition and binder resin.

According to the present invention, it is possible to provide a conductive composition with excellent durability and conductivity and low cost, and a conductive paste containing the conductive composition.

The form used to implement the invention

A. Conductive composition

The conductive composition of the present invention contains flake metal powder, salicylic acid compound and o-aminophenol.

In the conductive composition of the present invention, the flake metal powder is coated with a salicylic acid compound and added with o-aminophenol, so it is excellent in conductivity and durability (acid resistance, heat resistance, and moisture resistance). In particular, the advantage of moisture resistance is significant, and the above-mentioned conductive composition can maintain the conductivity of the flake metal powder even under high humidity.

A-1. Flake metal powder

The flake metal powder is in the form of flakes. By using flake-shaped metal powder, the contact between the metal powders is promoted, and a conductive composition with excellent conductivity can be obtained. In this specification, the term “sheet shape” refers to a shape similar to a flat plate or a thin rectangular parallelepiped, and specifically refers to a shape with an aspect ratio (major axis length L/thickness t) of 3 or more. The upper limit of the aspect ratio may be 300, for example. In addition, the long axis length L and thickness t of the flake metal powder can be measured by observing the SEM photograph of a scanning electron microscope (SEM).

The average particle size of the flake metal powder is 3 μm to 25 μm, preferably 5 μm to 20 μm, and more preferably 7 μm to 20 μm. If it is within this range, a conductive composition with excellent conductivity and durability can be obtained. In addition, the so-called average particle size refers to the particle size (primary particle size) at 50% of the integral value of the particle size distribution obtained by the laser diffraction scattering method.

Examples of the metal constituting the flake metal powder include copper, silver, gold, and nickel. Furthermore, it is also possible to use flake metal powder obtained from metal particles of a multilayer structure composed of two or more metals (for example, silver-coated copper particles). From the viewpoint of conductivity and cost, it is preferable to use flake copper powder.

The above-mentioned flake copper powder can be obtained by, for example, processing copper ions obtained by an optional appropriate method into a flake shape by an optional appropriate method. Make The method for producing copper particles before processing includes, for example, an atomization method, a wet reduction method, and an electrolysis method. The copper particles are preferably electrolytic copper particles obtained by electrolysis. If electrolytic copper particles are used, a conductive composition with higher conductivity can be obtained. The processing of copper particles can be carried out using a media mill such as a rotating ball mill, an attritor, and an SC mill. By using a media grinder for processing, there will be collision and shearing forces on the particles between the inner wall of the device and the media, and between the media. The extension, crushing, and agglomeration of the particles continue to be repeated, making the particles Was processed into flakes.

In one embodiment, the processing of copper particles (flaky copper particles) is performed after the copper particles are mixed with the above-mentioned specific amount of salicylic acid compound, or after the copper particles are mixed with the above-mentioned specific amount of salicylic acid compound At the same time (that is, processing and mixing at the same time). In this way, a conductive composition with excellent conductivity and durability can be obtained.

A-2. Salicylic acid compounds

In the conductive composition of the present invention, relative to 100 parts by weight of the flake metal powder, the content of the salicylic acid compound is 0.04 parts by weight to 1.6 parts by weight, preferably 0.07 parts by weight to 1.3 parts by weight, preferably It is 0.1 part by weight to 1 part by weight, more preferably 0.3 part by weight to 0.8 part by weight.

Examples of the above-mentioned salicylic acid compounds include salicylic acid, salylamine, salylhydroxamic acid, salylaldoxime, salylhydrazine, N,N'-bissalicylic hydrazine, and poly(N,N' -Salicylic acid derivatives such as bis-salanylhydrazine. Among them, salicylic acid is preferred.

In the present invention, by mixing the flake metal powder with a specific amount of salicylic acid compound, the flake metal powder and the salicylic acid compound will form a chelate structure. Therefore, the flake metal powder will be well covered. As a result, a conductive composition having excellent conductivity and durability can be obtained. In addition, such effects can be more pronounced by using flake copper powder as flake metal powder and salicylic acid as a salicylic acid compound.

A-3. O-Aminophenol

In the conductive composition of the present invention, relative to 100 parts by weight of the flake metal powder, the content ratio of the o-aminophenol is 1.2 parts by weight to 4.5 parts by weight, preferably 1.2 parts by weight to 4 parts by weight, more preferably 1.2 parts by weight to 3 parts by weight.

The conductive composition of the present invention can prevent oxidation of the flake metal powder by adding a specific amount of o-aminophenol, and has excellent durability (especially moisture resistance). The conductive composition of the present invention can maintain its conductivity after being placed for a long time under high humidity (for example, 90% RH).

In one aspect, the conductive composition is manufactured by adding the o-aminophenol to the copper particles as described in the item A-1. In another embodiment, the above-mentioned conductive composition is used when the copper particles are processed (that is, when the copper ions are flake-formed), the copper ions are combined with the above-mentioned specific amount of salicylic acid and the above-mentioned specific The amount of o-aminophenol is mixed and manufactured. By simultaneously performing the flake formation of copper ions and the mixing of the components, a conductive composition with excellent conductivity and durability can be obtained.

B. Conductive paste

The conductive paste of the present invention includes a conductive composition and a binder resin. As the conductive composition, the conductive composition described in the above item A is used.

As the binder resin, any suitable resin can be used.

In one aspect, a thermoplastic resin is used as the binder resin. Examples of thermoplastic resins include polyethylene, polypropylene, polyester, polyacrylate, polymethacrylate, and polyamide. These resins may be used alone or in combination of two or more kinds.

系樹脂、聚矽氧系樹脂、丙烯酸系樹脂、三聚氰胺系樹脂、尿素系樹脂等。該等樹脂可單獨使用，亦可將2種以上組合使用。其中較佳者為環氧系樹脂或酚系樹脂。作為環氧系樹脂，適合使用具有苯環、聯苯環、萘環等芳香族環之環氧系樹脂，更適合使用苯氧基樹脂。作為苯氧基樹脂，可舉例如使用屬於雙酚化合物之雙酚A所獲得之雙酚A型苯氧基樹脂、使用雙酚F所獲得之雙酚F型苯氧基樹脂。較佳為使用雙酚A型苯氧基樹脂。 In one aspect, a thermosetting resin is used as the binder resin. Examples of thermosetting resins include epoxy resins, phenolic resins, diallyl phthalate resins, unsaturated alkyd resins, urethane resins, and bismaleimide resins.

Resin, silicone resin, acrylic resin, melamine resin, urea resin, etc. These resins may be used alone or in combination of two or more kinds. Among them, epoxy resin or phenol resin is preferred. As the epoxy resin, an epoxy resin having an aromatic ring such as a benzene ring, a biphenyl ring, and a naphthalene ring is suitably used, and a phenoxy resin is more suitably used. As the phenoxy resin, for example, a bisphenol A type phenoxy resin obtained by using bisphenol A, which is a bisphenol compound, and a bisphenol F type phenoxy resin obtained by using bisphenol F, can be mentioned. Preferably, a bisphenol A type phenoxy resin is used.

As the above-mentioned phenoxy resin, one having a relatively large molecular weight (polymerization degree) is suitably used. The weight average molecular weight of the phenoxy resin may be, for example, 10,000 or more, preferably 30,000 or more, preferably 35,000 or more, and more preferably 35,000 to 600,000. If a high molecular weight phenoxy resin is used, a conductive paste with excellent heat resistance can be obtained. In addition, high-molecular-weight epoxy resins tend to harden easily (the hardening temperature is lower and the hardening time is shorter), which is advantageous. The weight average molecular weight can be obtained by GPC (solvent: THF) measurement.

Relative to 100 weight of flake metal powder in conductive composition The content of the binder resin is preferably 8 parts by weight to 25 parts by weight, preferably 10 parts by weight to 12 parts by weight.

The conductive paste of the present invention may further contain a coupling agent. By adding a coupling agent, the oxidation of the flake metal powder can be prevented. As the coupling agent, a silane-based coupling agent or a titanium-based coupling agent can be used, and a titanium-based coupling agent is preferably used. As the silane coupling agent, vinyl trichlorosilane, vinyl trimethoxysilane, vinyl triethoxy silane, 2-(3,4 epoxycyclohexyl) ethyl trimethoxy silane, 3- Glycidoxy propyl trimethoxy silane, 3-glycidoxy propyl methyl diethoxy silane, 3-glycidoxy propyl triethoxy silane, 3-methacrylate Propyl methyl dimethoxy silane, 3-methacrylate propyl trimethoxy silane, 3-methacrylate propyl methyl diethoxy silane, 3-methacrylate propyl triethoxy Silane, 3-acrylic propyl trimethoxy silane, N-2 (amino ethyl) 3-aminopropyl methyl dimethoxy silane, N-2 (amino ethyl) 3-amino Propyl trimethoxy silane, N-2 (amino ethyl) 3-aminopropyl triethoxy silane, 3-amino propyl trimethoxy silane, 3-amino propyl triethoxy silane , 3-Mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl) tetrasulfide, etc. As the titanium coupling agent, for example, isopropyl tristearyl titanate, isopropyl ginseng (dioctyl pyrophosphate) titanate, isopropyl tris(N-aminoethyl‧amino group) Ethyl) titanate, tetraoctyl bis (ditridecyl phosphate) titanate, tetrakis (2-2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphoric acid Ester titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) vinyl titanate, etc.

The conductive paste of the present invention may further contain a solvent. In a In the implementation aspect, a solvent that can dissolve the binder resin can be selected. By adding such a solvent, the fluidity of the conductive paste can be controlled. Specific examples of the above-mentioned solvent include organic solvents such as butyl carbitol, ethyl carbitol, and γ-butyrolactone. A solvent may be used individually by 1 type, and may be used in combination of 2 or more types.

The conductive paste of the present invention may also contain optional appropriate other additives. Examples of other additives include defoamers, antioxidants, viscosity modifiers, diluents, anti-precipitation agents, leveling agents, coupling agents, and the like.

In one aspect, the conductive paste further includes a defoamer. Examples of the defoaming agent include silicon-based defoaming agents and acrylic defoaming agents. The amount of defoamer added is not limited, but the minimum amount necessary for defoaming during screen printing is better.

The conductive paste of the present invention can be produced by an optional suitable method. For example, a phenoxy resin can be dissolved in a solvent to prepare a varnish, and the conductive composition can be added to the varnish and stirred to obtain it. As a stirring method, a method using a self-revolution mixer, three drums, kneader, etc. can be adopted.

As a representative, the conductive paste of the present invention can be used for coating on a transparent conductive film. For example, on a transparent conductive layer (such as an ITO layer) formed on a transparent conductive film, the conductive paste is applied by any appropriate method, and then heated and hardened for use. Examples of the above-mentioned coating method include printing methods such as screen printing, bending printing, and gravure printing; spray coating, brush coating, and bar coating. Preferably, a screen printing method is used.

Example

The following examples illustrate the present invention in detail, but the present invention is not limited by these examples. Also, in the examples, if there is no special description, "parts" And "%" is the weight basis.

[Example 1]

300 g of copper particles (manufactured by Mitsui Metal Mining Co., Ltd., trade name "ECY") and 0.9 g of salicylic acid were put into a ball mill (capacity: 300 mL, 5 mmφ alumina ball about 300 g), and mixed operation was performed for 5 hours. Through this operation, a mixture of flaky copper powder and salicylic acid is obtained, wherein the flaky copper powder is obtained by repeated expansion, crushing, and agglomeration of copper particles. To the obtained mixture, 7.5 g of o-aminophenol was added to obtain a conductive composition.

[Example 2]

Except that the blending amount of salicylic acid was 0.15 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 3]

Except that the blending amount of salicylic acid was 0.3 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 4]

Except that the blending amount of salicylic acid was 1.5 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 5]

Except that the blending amount of salicylic acid was set to 2.1 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 6]

Except for setting the blending amount of salicylic acid to 3 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 7]

Except that the blending amount of salicylic acid was 4.5 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 8]

Except that the blending amount of o-aminophenol was 4.5 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 9]

Except for setting the blending amount of o-aminophenol to 10.5 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Example 10]

Except for setting the blending amount of o-aminophenol to 13.5 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 1]

Except for not blending salicylic acid, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 2]

Except for setting the blending amount of salicylic acid to 0.06 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 3]

Except that the blending amount of salicylic acid was 5.1 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 4]

300 g of copper particles (manufactured by Mitsui Metal Mining Co., Ltd., trade name "ECY") and 0.9 g of o-aminophenol were put into a ball mill (capacity: 300 mL, 5 mmφ alumina ball about 300 g), and mixed operation was performed for 5 hours. Through this operation, the copper particles are obtained A mixture of flake copper powder and salicylic acid obtained after repeated expansion, crushing and agglomeration. To the obtained mixture, 7.5 g of o-aminophenol was added to obtain a conductive composition.

[Comparative Example 5]

Except having used 0.9 g of oxalic acid instead of 0.9 g of salicylic acid, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 6]

Except having used 0.9 g of oleic acid instead of 0.9 g of salicylic acid, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 7]

Except having used 0.9 g of triethanolamine instead of 0.9 g of salicylic acid, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 8]

Except that the blending amount of o-aminophenol was 0.3 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 9]

Except that the blending amount of o-aminophenol was 3 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 10]

Except that the blending amount of o-aminophenol was 15 g, the same procedure as in Example 1 was carried out to obtain a conductive composition.

[Comparative Example 11]

300 g of spherical copper particles (manufactured by Mitsui Metal Mining Co., Ltd., trade name "MA-C05K"), 0.9 g of salicylic acid, and 7.5 g of o-aminophenol were mixed to obtain Conductive composition.

<evaluation>

The conductive compositions obtained in the examples and comparative examples were prepared into conductive pastes, and the conductive pastes were evaluated as follows. The results are shown in Table 1.

(1) Volume resistivity (initial)

An epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "JER1256", bisphenol A type phenoxy resin) and butyl carbitol were mixed to prepare a varnish. The conductive composition obtained in the above manner is added to the varnish to obtain a conductive paste. In addition, the epoxy resin (solid content) in the conductive paste was blended so as to be 10 parts by weight with respect to 100 parts by weight of the flake copper powder (copper particles in Comparative Example 10).

The conductive paste was printed in a line between the two copper electrodes formed on the PET substrate, and then heated at 120° C. for 10 minutes in an air oven to obtain a measurement sample.

The printing adopts screen printing, using 180 mesh polyester screen. The line is 10mm wide and 60mm long.

The resistance value between the electrodes is measured by the 4-terminal method. From the obtained resistance value, the volume resistivity was calculated by the following formula.

Volume resistivity σ=W×D×R/L

σ: Volume resistivity (Ω‧cm)

W: width of coating film (cm)

D: coating thickness (cm)

L: Coating film length (cm)

R: measured resistance value (Ω)

(2) Volume resistivity (after humidity test)

The conductive composition obtained from the Examples and Comparative Examples was placed in an environment of 40° C./90% RH for 168 hours. Except for using the conductive composition after being left under such high humidity, the same procedure as the above-mentioned evaluation (1) was performed to prepare a conductive paste, and the volume resistivity of the conductive paste was measured.

It can be seen from Table 1 that by using the conductive composition of the present invention, a conductive paste having excellent durability and conductivity can be obtained.

Claims (3)

A conductive composition comprising flake metal powder, salicylic acid compound and o-aminophenol, and containing salicylic acid as the salicylic acid compound; and, relative to 100 parts by weight of the flake metal powder, the salicylic acid The content ratio of the compound is 0.04 parts by weight to 1.6 parts by weight; relative to 100 parts by weight of the flake metal powder, the content ratio of the o-aminophenol is 1.2 parts by weight to 4.5 parts by weight. The conductive composition according to claim 1, wherein as the aforementioned flake metal powder, flake copper powder is contained. A conductive paste comprising the conductive composition of claim 1 or 2 and a binder resin.