JP2018092864A - Copper paste composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper paste composition that makes it possible to obtain a copper cured film that has excellent flexibility after curing and therefore has excellent breaking resistance on a fiber substrate such as paper prone to expansion due to moisture absorption, and also shows high conductivity.SOLUTION: A copper paste composition contains a specific surface-coated copper particle (A), a resol type phenol resin (B), a vinylphenol polymer (C), a chelating agent (D), a solvent (E), and a flexibilizer (F). Based on 100 pts.mass of (A), the content of (B) is 10-25 pts.mass, (C) is 0.5-3.0 pts.mass, (D) is 0.5-3.0 pts.mass, (E) is 10-40 pts.mass, and (F) is 0.5-3.0 pts.mass.SELECTED DRAWING: None

Description

  The present invention relates to a copper paste composition capable of obtaining a copper wiring that maintains high conductivity on a fiber substrate such as paper even in a high humidity environment.

  Conventionally, in the field of electronic materials, a conductive paste composition mainly composed of a conductive metal is used as a resin film of a substrate as a means for ensuring electrical continuity such as formation of a conductive pattern of an RFID (radio frequency identifier) tag. For example, a method for printing on a network is widely used.

  However, with the recent progress of disposable use of RFID tags, there is a demand for further cost reduction of RFID tags, and it is possible to produce a tag on a fiber substrate such as paper that is cheaper than a resin substrate such as PET. There is a need for an adhesive paste composition.

  When an RFID tag is produced by printing a conductive paste composition on a fiber substrate, the conductive paste composition is required to have a cured film with excellent flexibility. For example, in the case of a fiber substrate such as paper whose dimensions change greatly due to swelling due to moisture absorption in a high-humidity environment, if the cured film has low flexibility, the deformation of the cured film follows the change in the substrate dimensions. This is because it is difficult to maintain electrical conductivity due to disconnection.

  The conductive paste composition is a fluid composition containing metal particles, and has excellent oxidation resistance and low volume resistivity, and thus a silver paste using silver has been generally used. However, silver as a raw material is very expensive as a rare metal, and the price of the silver paste is proportionally expensive. Therefore, in recent years, development of copper paste using copper having a lower raw material price has been actively conducted.

  Patent document 1 is disclosing the copper paste which uses only the resol type phenol resin which is a thermosetting resin as a binder. Since the copper paste is made from copper, the cured product that forms is easier to oxidize than the silver paste, and the conductivity is reduced. Therefore, thermosetting resins such as phenolic resins that are easy to ensure conductivity are used.

  Patent Document 2 discloses a conductive paste excellent in flexibility using only an elastomer such as rubber that is not crosslinked as a binder.

JP-A-11-224532 JP2014-236103

  The cured product obtained by curing the copper paste disclosed in Patent Document 1 has poor flexibility because the binder forms a strong network by three-dimensional crosslinking, and there is a concern about the disconnection described above, and the RFID tag on the fiber substrate Formation becomes difficult. In the conductive paste disclosed in Patent Document 2, the copper paste using copper particles as the conductive particles is excellent in the flexibility of the cured product, but the copper is oxidized because the binder does not have reducing properties. It becomes easy to obtain good conductivity.

  Therefore, an object of the present invention is to obtain a copper cured film that has good flexibility after curing, and thus has excellent disconnection resistance on a fiber substrate such as paper that easily expands due to moisture absorption and exhibits high conductivity. The object is to provide a copper paste composition.

  As a result of intensive studies, the present inventors have formulated the above-mentioned disconnection resistance of the cured copper film by blending specific copper particles coated with a specific coating agent using a specific coating method and a specific component. The present inventors have found that a copper paste composition that can achieve both high conductivity can be produced, and have completed the present invention.

That is, according to the present invention, the surface-coated copper particles (A), the resol type phenol resin (B), the vinylphenol polymer (C), the chelating agent (D), the solvent (E), and the flexibility imparting agent. The first coating of the amine compound represented by the formula (1) containing (F), wherein the surface-coated copper particles (A) are bonded to copper on the surfaces of the copper particles by chemical bonds and / or physical bonds. A second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms bonded to the amine compound by a chemical bond on the first coating layer, and the surface-coated copper particles (A ) 10 to 25 parts by mass of the resol-type phenolic resin (B), 0.5 to 3.0 parts by mass of the vinylphenol polymer (C), 0.5 parts of the chelating agent (D) with respect to 100 parts by mass. -3.0 parts by mass, the solvent (E) 10-40 The amount unit, and containing the flexible imparting agent (F) 0.5 to 3.0 parts by weight, the copper paste composition is provided.

[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]

The vinylphenol polymer (C) is preferably a homopolymer of vinylphenol and one or more monomers selected from vinylphenol and styrene, butyl acrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate. And at least one polymer selected from the group consisting of copolymers, wherein the polymer has a structural unit represented by the formula (2) and has a weight average molecular weight of 1,000 to 20,000. is there.

  The chelating agent (D) is preferably at least one compound selected from aromatic diamines and Schiff bases.

  The flexibility imparting agent (F) is preferably at least one compound selected from phosphoric acid esters, phthalic acid esters, polyether esters, and adipic acid esters.

When the flexibility-imparting agent (F) is a polyether ester and / or an adipic acid ester, a polyether ester having a weight average molecular weight of 450 to 650 represented by the formula (3), and a formula (4) and / or ( It is preferable that it is at least 1 or more types of compound selected from the adipic acid ester of the weight average molecular weight 200-3,000 represented by 5).

Wherein (3), ^{R 1} and ^{R 3} are each _{independently, - (CH 2) a -CH} 3, or _- represents a _{(CH 2) b -C 6 H} 5. a is an integer of 0 to 7, and b is an integer of 0 to 4. R ² represents — (CH ₂ ) _c —. c is an integer of 2-4. x is an integer of 1-6. ]

[In Formula (4), R ⁴ and R ⁵ each independently represent — (CH ₂ ) _d — (CR ⁶ R ⁷ ) _e — (CH ₂ ) _f —CH ₃ . Here, R ⁶ and R ⁷ each independently represent a hydrogen atom or — (CH ₂ ) _g —CH ₃ . D is an integer of 0 to 4, e is an integer of 0 to 2, f is an integer of 0 to 4, and g is an integer of 0 to 3. ]

Wherein (5), ^{R 8} and ^{R 9} each independently represents - _{(CH 2) j -CH 3 -} (CH 2) h - (CR 11 R 12) i. Here, R ¹¹ and R ¹² each independently represent a hydrogen atom or — (CH ₂ ) _k —CH ₃ . H is an integer of 0 to 4, i is an integer of 0 to 2, j is an integer of 0 to 4, and k is an integer of 0 to 3. R ¹⁰ represents — (CH ₂ ) ₁ —. l is an integer of 2-4. y is an integer of 1 to 4, and z is an integer of 1 to 4. ]

Since the surface-coated copper particles (A) which are components of the copper paste composition of the present invention have the specific first and second coating layers, the surface of the copper particles is difficult to be oxidized, and in a high-temperature and high-humidity environment. Has excellent oxidation resistance against external factors such as heat and moisture. Therefore, the cured copper film obtained by curing the copper paste composition of the present invention can maintain high conductivity.
Furthermore, since the copper paste composition of the present invention contains the surface-coated copper particles (A) and the specific component in a specific blending ratio, a cured copper film having high flexibility can be obtained. Therefore, when a copper cured film is formed on a fiber substrate, even when the fiber substrate absorbs moisture and expands in a high-temperature and high-humidity environment, it can follow the deformation of the substrate and exhibits excellent disconnection resistance. .
That is, since the copper paste composition of the present invention can obtain a cured copper film that has both high resistance to disconnection and high conductivity, an RFID tag using a fiber substrate such as paper can be manufactured.
In the present invention, the copper cured film is not a cured film made only of copper, but copper, the coating layer that contributes to maintaining high conductivity, and some components in the copper paste composition that contribute to flexibility. It means the cured film contained.

It is a figure showing the IR spectrum measurement result of the surface of the surface covering copper particle (A) used in the Example. It is a figure showing IR spectrum measurement result of ethylenediamine. It is a figure showing the external appearance observation result after high temperature high humidity environment exposure of the copper cured film of Example 1 on a paper substrate. It is a figure showing the external appearance observation result after high temperature high humidity environment exposure of the copper cured film of the comparative example 1 on a paper board | substrate.

Hereinafter, embodiments of the present invention will be described in detail.
<Constituent components of copper paste composition>
[Surface-coated copper particles (A); hereinafter simply referred to as (A)]
The copper particles before surface coating for (A) have an average particle diameter D50 of 1 to 10 μm. D50 is preferably 4 μm or more and 7 μm or less. The smaller the average particle size, the smoother the surface of the cured copper film, and the surface effect in the high frequency region can be suppressed. However, on the other hand, the specific surface area of the particles increases and the surface of the particles is likely to be covered by non-conductive copper oxide due to oxidation, which may reduce the conductivity of the wiring to be formed. Therefore, if D50 is less than 1 μm, the conductivity of the wiring may be lowered. On the other hand, if D50 exceeds 10 μm, the conductivity can be secured, but the surface of the cured copper film becomes rough, the surface effect in the high frequency region becomes larger, and the antenna performance may be deteriorated.
Hereinafter, unless otherwise specified, the term “copper particles” refers to the copper particles before surface coating as a raw material.

  In the present specification, the particle diameter and the average particle diameter D50 indicate values measured by a laser diffraction type microtrack particle diameter distribution measuring apparatus. Examples of the measuring apparatus include Microtrack particle size distribution measuring apparatus MT3000II series (laser diffraction / scattering method) manufactured by Microtrack Bell Co., Ltd.

Examples of the copper particles used in the present invention include known copper particles generally used for copper paste and copper ink. The shape may be any of a spherical shape, a plate shape, a dendritic shape, a rod shape, and a fibrous shape, and may be an indefinite shape such as a hollow shape or a porous shape. Furthermore, a core-shell shape in which the shell is copper and the core is a material other than copper may be used. In particular, in the case of a copper paste composition prepared using plate-like particles, when a copper cured film is formed to form wiring on the substrate, the plane direction of the copper paste composition due to the particle shape It is particularly preferable to use plate-like particles because the curing shrinkage is suppressed and deformation is suppressed and adhesion to the substrate is excellent. In this specification, the definition of the plate-like particle is that the value of the ratio “D50 / average thickness” between the average particle diameter D50 of the copper particles and the average thickness of the particles is 1.5 to 20. In the present specification, the thickness of the particle means a length in a direction perpendicular to the planar spread of the plate-like particle. In addition, the average thickness of the particles is the measured value of the thickness of the particles calculated by image analysis by selecting arbitrary 100 particles in the observation result image of the particles obtained by scanning electron micrograph (SEM) observation. Average value.
Moreover, although the copper particle used for (A) may be one kind, you may mix and use the copper particle of a different shape.

(A) is a first coating layer of an amine compound represented by formula (1) that is bonded to copper on the surface of the copper particles by chemical bonding or physical bonding, and the amine compound is formed on the first coating layer. And a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms bonded by a chemical bond.

[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]

The first coating layer (A) is a layer of an amine compound that is chemically and / or physically bonded and adsorbed to copper on the surface of the copper particles. From the viewpoint of oxidation resistance, it is ideal that the amine compound is uniformly coated on the copper particle surface in the form of a monomolecular film. However, in practice, it is difficult to achieve such an ideal state. There may be a portion where the amine compound is not adsorbed on the copper surface, or there may be a portion where two or more molecules are laminated and adsorbed.
Therefore, the first coating layer in the present invention includes not only a layer in which the amine compound uniformly coats the copper surface but also a coating layer in which a copper surface on which the amine compound is not adsorbed partially exists.
In addition, it shall confirm by IR measurement of the copper surface mentioned later that the amine compound adsorb | sucks on the copper surface, and forms the 1st coating layer.

Here, the adsorption by the chemical bond indicates that the amine compound forms a bond by electrostatic interaction with the copper surface and is adsorbed on the copper surface. The electrostatic interaction as used herein refers to hydrogen bonding, interaction between ions (ionic bonding), and the like. Moreover, adsorption | suction by a physical coupling | bonding refers to adsorb | sucking to the copper surface by the physical adsorption | suction by van der Waals force. In particular, the amino group has a high electron donating property, and it is considered that the amino group forms a bond by forming a coordination to copper. Therefore, the amine compound mainly forms a bond on the copper surface by a chemical bond by electrostatic interaction. It is considered that the first coating layer is formed by adsorption. However, there may be some adsorption due to physical bonding.
Further, there may be a portion in which two or more molecules of amine compounds are bonded by, for example, hydrogen bonding.

The second coating layer (A) is a layer laminated on the first coating layer, and is an aliphatic monocarboxylic acid having 8 to 20 carbon atoms that is bonded to the amine compound of the first coating layer by a chemical bond. Of layers.
Here, the chemical bond means that the carboxyl group of the aliphatic monocarboxylic acid and the amino group of the amine compound are bonded by electrostatic interaction. The electrostatic interaction as used herein refers to hydrogen bonding, interaction between ions (ionic bonding), and the like. That is, the second coating layer is a layer of an aliphatic monocarboxylic acid bonded to the amine compound of the first coating layer by electrostatic interaction. Ideally, it is preferable that the amine compound of the first coating layer and the aliphatic monocarboxylic acid react with each other at a ratio of 1: 1 to form the second coating layer. It is difficult to become. Accordingly, there may be an amine compound in the first coating layer that is not partially bonded to the aliphatic monocarboxylic acid, and in the second coating layer, two or more molecules of the aliphatic monocarboxylic acid are laminated by physical adsorption or the like. There may be a portion that is adsorbed.
Therefore, the second coating layer in the present invention is not only a layer in which the aliphatic monocarboxylic acid uniformly covers the first coating layer, but also the aliphatic monocarboxylic acid is an amine compound, as in the first coating layer. It also includes a coating layer formed so that a part that is not bonded is partially present.
In addition, it shall confirm by IR measurement of the copper surface mentioned later that the aliphatic monocarboxylic acid adsorb | sucks and forms the 2nd coating layer similarly to the 1st coating layer.

  Furthermore, when there is a part of the copper surface to which the amine compound is not bonded, there may be a portion where the aliphatic monocarboxylic acid is directly adsorbed on the copper surface, and such surface-coated copper particles are also present. It is (A) within the scope of the invention.

  The amine compound that forms the first coating layer is an amine compound represented by the above formula (1). Specifically, hydrazine, methylenediamine, ethylenediamine, 1,3-propanediamine, dimethylenetriamine, trimethylenetetraamine, tetramethylenepentamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, dipropylenetriamine, triethylene Examples include propylene tetraamine and tetrapropylene pentaamine. A 1st coating layer may be formed with one type of amine compound among these, and may be formed using a plurality of types.

  When the value of m in the formula (1) is 4 or more, the number of amino groups per unit area on the copper particle surface of amino groups contributing to chemical bonding and reducing properties decreases, so that the desired oxidation resistance May become insufficient, and copper surface oxidation may easily proceed. Further, when n in the formula (1) is 3 or more, the molecular chain becomes too long, resulting in steric hindrance with the adjacent amine compound during coating, and the copper particle surface cannot be sufficiently coated. Therefore, there is a possibility that the surface oxidation of copper is likely to proceed.

The aliphatic monocarboxylic acid having 8 to 20 carbon atoms forming the second coating layer used in the present invention is a linear saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms or linear unsaturated group having 8 to 20 carbon atoms. Examples thereof include aliphatic monocarboxylic acids, branched saturated aliphatic monocarboxylic acids having 8 to 20 carbon atoms, and branched unsaturated aliphatic monocarboxylic acids having 8 to 20 carbon atoms. Specific examples of the linear saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, and margarine. Examples include acid, stearic acid, nonadecanoic acid, and arachidic acid. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include myristoleic acid, palmitoleic acid, petroceric acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include 2-ethylhexanoic acid. The said aliphatic monocarboxylic acid may be used by 1 type, and may mix and use several types.
If the carbon number is 7 or less, the dispersibility of the surface-coated copper particles may be low because the alkyl chain length is short. In addition, when the number of carbon atoms is 21 or more, the aliphatic monocarboxylic acid becomes more hydrophobic, so the compatibility with the binder is increased. When the copper paste composition is formed, the aliphatic monocarboxylic acid is detached from the second coating layer. Elution to the binder side.

  In order to further improve the dispersibility of the copper paste composition (A) in the copper paste composition and to reduce the amount of free aliphatic monocarboxylic acid in the copper paste composition, an aliphatic group having 10 to 18 carbon atoms is used. Monocarboxylic acids are preferred. Furthermore, linear saturated aliphatic monocarboxylic acids have a finer packing structure than aliphatic monocarboxylic acids having branched chains and unsaturation, and are covered with fewer voids, so that they are linear saturated fatty acids having 10 to 18 carbon atoms. More preferably, an aromatic monocarboxylic acid is used for the coating.

(A) shows that two coating layers of a first coating layer of an amine compound represented by the formula (1) and a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms are on the surface of the copper particles. It is characteristic that it is formed.
The amine compound has an effect of removing an oxide on the metal surface and an effect of suppressing oxidation because the amino group has reducibility.
In addition, the amine compound has a higher coordination ability to the metal than the aliphatic monocarboxylic acid due to the effect of the lone pair of nitrogen of the amino group and binds to the copper surface with a stronger bond than the aliphatic monocarboxylic acid. It is considered that the surface coverage is higher than that of carboxylic acid. Moreover, an amine compound tends to form a bond by an electrostatic interaction with an aliphatic monocarboxylic acid. Here, the electrostatic interaction refers to a hydrogen bond and an ion-ion interaction. Therefore, after coating the copper surface with an amine compound having a high surface coverage, the outer surface is further coated with an aliphatic monocarboxylic acid, so that the surface coating is higher than the direct coating of the aliphatic monocarboxylic acid on the copper particles. The aliphatic monocarboxylic acid can be coated on the copper particles at a high rate. Therefore, the surface-coated copper particles of the present invention have higher oxidation resistance than copper particles coated only with aliphatic monocarboxylic acid due to the oxidation-inhibiting effect of the amine compound and the high coverage of aliphatic monocarboxylic acid. Yes.

  Furthermore, as described above, the aliphatic monocarboxylic acid is considered to have its carboxyl group bonded to the amino group of the amine compound by electrostatic interaction. That is, it is considered that the second coating layer is formed with the carboxyl group of the hydrophilic group facing the first coating layer side of the amine compound and the alkyl group of the hydrophobic group facing the outside. Therefore, the (A) of the present invention having the second coating layer of the aliphatic monocarboxylic acid can suppress the aggregation of the copper particles and also suppress the elimination of the amine compound, as compared with the copper particles coated only with the amine compound. be able to.

It can be confirmed that (A) is coated with an amine compound and an aliphatic monocarboxylic acid by measuring an infrared absorption (IR) spectrum of the surface-coated copper particles.
As an example, FIG. 1 shows an IR spectrum of surface-coated copper particles coated with ethylenediamine and myristic acid (surface-coated copper particles used in Examples described later).
When the amine compound used for coating is measured alone, the peak of N—H bending vibration appears at 1598 cm ⁻¹ (FIG. 2), whereas the N—H change observed in the surface-coated copper particles. The peak of angular vibration is shifted to the low wavenumber side of 1576 cm ⁻¹ , indicating that the amine compound is present on the copper particle surface. Further, in FIG. 1, the peak of C═O stretching vibration of the aliphatic monocarboxylic acid is not observed at 1700 cm ^−1, and the peak of the carboxylic acid anion (—COO ⁻ ) is observed near 1400 cm ^−1. It shows that the acid is present by binding with the amine compound by electrostatic interaction.

[Resol type phenol resin (B); hereinafter, it may be simply referred to as (B)]
(B) is a component that acts as a binder, and the content of (B) in the copper paste composition is preferably 10 to 25 parts by mass and more preferably 15 to 20 parts by mass with respect to 100 parts by mass of (A). preferable. If content of (B) is 10 mass parts or more, the adhesiveness of copper particles when it is set as a copper cured film is favorable, and it has sufficient fluidity at the time of printing of a copper paste composition. Moreover, if it is 25 mass parts or less, the copper resistance film | membrane of a low resistance value will be easy to be obtained with the reducibility which (B) has.
(B) can be suitably produced according to a known method, but can also be obtained as a commercial product.
Examples of commercially available resol type phenol resins include RESITOP (registered trademark) PL-5208, PL-2211, and PL-6220 (manufactured by Gunei Chemical Industry Co., Ltd.).

[Vinylphenol polymer (C); hereinafter, it may be simply referred to as (C)]
(C) is a component that acts as a binder with (B), and the content of (C) in the copper paste composition is preferably 0.5 to 3.0 parts by mass with respect to 100 parts by mass of (A) 0.8 to 2.0 parts by mass is more preferable. If the content of (C) is 0.5 parts by mass or more, since (B) and (C) cross-link using the hydroxyl group of each as a starting point, it is more straightforward than the cured copper film formed only by (B). It is considered that the content of the chain polymer increases and the crosslinking density decreases. Therefore, it is possible to obtain a copper-cured film having excellent flexibility and a high resistance to disconnection that can follow the deformation of the substrate even when the fiber material of the substrate absorbs moisture and swells in a high humidity environment. However, if it exceeds 3.0 parts by mass, the dispersibility of (A) in the copper paste composition may be reduced and the uniform dispersibility may be reduced, and the conductivity of the cured copper film after curing is reduced. there is a possibility.

(C) preferably comprises a homopolymer of vinylphenol and a copolymer of vinylphenol and one or more monomers selected from styrene, butyl acrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate. It is at least one polymer selected from the group, and the polymer preferably has a structural unit represented by the formula (2) and has a weight average molecular weight of 1,000 to 20,000. The weight average molecular weight is more preferably 8,000 to 15,000. When the weight average molecular weight is within this range, the obtained copper cured film is excellent in break resistance.

  (C) When using a copolymer, it is preferable that content of vinylphenol is 50 mol% or more and less than 100 mol%. When the content of vinylphenol in the copolymer is less than 50 mol%, the compatibility with (B) resol type phenol resin may be reduced, and (A) the surface-coated copper particles may be non-uniformly dispersed. It may be difficult to secure the path, and the conductivity as a cured film may be reduced.

  As (C), it is particularly preferable to use a vinylphenol homopolymer from the viewpoint of conductivity and flexibility.

The vinylphenol homopolymer (C), which is a preferred embodiment, and the above copolymer can be produced according to known methods, but are also commercially available.
Examples of such commercially available products include Marcalinker (MARUKA LYNCUR: registered trademark) S-1 (vinylphenol homopolymer, weight average molecular weight 2,000), Marcalinker S-4P (vinylphenol homopolymer, weight average molecular weight). 9,500), Marcalinker CBA (copolymer of 55 mol% vinylphenol and 45 mol% butyl acrylate, weight average molecular weight 12,500), Marcalinker CMM (copolymer of 55 mol% vinylphenol and 45 mol% methyl methacrylate, weight average molecular weight) 10,000), and Marcalinker CHM (a copolymer of 55 mol% vinylphenol and 45 mol% 2-hydroxyethyl methacrylate, weight average molecular weight 10,000) (manufactured by Maruzen Petrochemical Co., Ltd.) Can do.
When these commercially available products are used as (C), Marcalinker S-4P is particularly preferable.

  Other examples of commercially available products in (C) include NISSO (registered trademark) VP-Polymer VP-8000 (vinylphenol homopolymer, weight average molecular weight 12,000), NISSO VP-Polymer VP-15000 (vinylphenol). Homopolymer, weight average molecular weight 19,000) (manufactured by Nippon Soda Co., Ltd.).

  When using the said commercial item as (C), any one of the above may be used, and two or more types may be mixed and used.

[Chelating agent (D); hereinafter may be simply referred to as (D)]
0.5-3.0 mass parts is preferable with respect to 100 mass parts of (A), and, as for content of (D) in a copper paste composition, 1.0-2.0 mass parts is more preferable. If content of (D) is 0.5 mass part or more, favorable antioxidant performance will be exhibited and it will become easy to obtain a highly conductive copper cured film. However, if it exceeds 3.0 parts by mass, the storage stability of the paste composition may be reduced.

  (D) is preferably at least one compound selected from aromatic diamines and Schiff bases.

  As the aromatic diamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, 2,3,5,6-tetramethyl 1,4-phenylenediamine, N, N-dimethyl-1,4-phenylenediamine, N, N, N′N′-tetramethyl-1,4-phenylenediamine, N, N′-diphenyl-1,4- Examples include phenylenediamine. In particular, it is preferable to use at least one selected from 1,2-phenylenediamine, 1,3-phenylenediamine, and 1,4-phenylenediamine from the viewpoint of conductivity, and 1,4-phenylenediamine is more preferable.

  As the Schiff base, N, N′-bis (salicylidene) ethylenediamine, N, N′-bis (salicylidene) -1,2-propanediamine, N, N′-bis (salicylidene) -1,3-propanediamine, N, N′-bis (salicylidene) -1,2-phenylenediamine and the like can be mentioned. In particular, it is preferable to use at least one selected from N, N′-bis (salicylidene) ethylenediamine and N, N′-bis (salicylidene) -1,2-propanediamine from the viewpoint of conductivity. N, N ′ -Bis (salicylidene) -1,2-propanediamine is more preferred.

  As (D), any one of these may be used, or two or more kinds may be mixed and used.

[Solvent (E); hereinafter may be simply referred to as (E)]
10-40 mass parts is preferable with respect to 100 mass parts of (A), and, as for content of (E) in a copper paste composition, 10-20 mass parts is more preferable.
In the copper paste composition of the present invention, when light or heat is applied, shrinkage occurs with the volatilization of the solvent and the curing of the binder, and the copper particles approach each other due to the shrinkage and develop conductivity. Therefore, the amount of the solvent is preferably as small as possible in order to develop conductivity, but the above range is preferable in terms of the viscosity suitable for the coating property to the substrate.
(E) is not particularly limited as long as it dissolves (B), (C), (D) and (F) described later. For example, ether alcohols, non-ether alcohols, esters , Ketones, terpenes, and other hydrocarbons.

Examples of ether alcohols include diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene Glycol methyl ethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether Seteto, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and propylene glycol monomethyl ether, and the like.
Excellent solubility of components (B) and (C) that act as binders, and moderate solvent volatility, good suitability for continuous printing by screen printing, etc., and good conductivity of cured copper film after heat curing In view of the above, diethylene glycol monoethyl ether and diethylene glycol monomethyl ether acetate are preferred.

  Examples of the non-ether alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, and triethylene glycol. Excellent solubility of components (B) and (C) that act as binders, and moderate solvent volatility, good suitability for continuous printing by screen printing, etc., and good conductivity of cured copper film after heat curing From the viewpoint of being 1,4-butanediol is preferable.

  Examples of the esters include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate. Excellent solubility of components (B) and (C) that act as binders, and moderate solvent volatility, good suitability for continuous printing by screen printing, etc., and good conductivity of cured copper film after heat curing In view of the above, butyl acetate is preferred.

  Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Excellent solubility of components (B) and (C) that act as binders, and moderate solvent volatility, good suitability for continuous printing by screen printing, etc., and good conductivity of cured copper film after heat curing From the viewpoint of being, cyclohexanone is preferable.

  Examples of terpenes include terpine oil, terpineol, borneol, and α-pinene. Excellent solubility of components (B) and (C) that act as binders, and moderate solvent volatility, good suitability for continuous printing by screen printing, etc., and good conductivity of cured copper film after heat curing From this viewpoint, terpineol is preferable.

  Other hydrocarbons include tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, diacetone alcohol, and propylene carbonate. Is mentioned. Excellent solubility of components (B) and (C) that act as binders, and moderate solvent volatility, good suitability for continuous printing by screen printing, etc., and good conductivity of cured copper film after heat curing From the viewpoint of being, octane is preferable.

  As (E), any one of these may be used, or two or more kinds may be mixed and used. In particular, it is preferable to use one or more selected from ether alcohols, esters or terpenes.

[Flexibility imparting agent (F); hereinafter may be simply referred to as (F)]
The content of (F) in the copper paste composition is preferably 0.5 to 3.0 parts by mass and more preferably 1.0 to 2.0 parts by mass with respect to 100 parts by mass of (A). If the content of (F) is 0.5 parts by mass or more, it gives flexibility to the cross-linked reaction product by (B) and (C) in the formed copper cured film, and copper having high disconnection resistance A cured film is easily obtained. However, if it exceeds 3.0 parts by mass, the conductivity of the copper cured film may be reduced due to an increase in the non-conductive component.

  (F) is preferably at least one compound selected from phosphoric acid esters, phthalic acid esters, polyether esters, and adipic acid esters, and more preferably phosphoric acid esters.

  Examples of phosphoric acid esters include triphenyl phosphate, tricresyl phosphate, mono (2-ethylhexyl) phosphate, bis (2-ethylhexyl) phosphate, tris (2-ethylhexyl) phosphate, etc. Tris (2-ethylhexyl) is preferred.

  Examples of the phthalic acid ester include dibutyl phthalate, diheptyl phthalate, bis (2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and the like, and bis (2-ethylhexyl) phthalate is particularly preferable.

As the polyether ester, a polymer having a weight average molecular weight of 450 to 650 represented by the following formula (3) is preferable.

In formula (3), R ¹ and R ³ each independently represent — (CH ₂ ) _a —CH ₃ or — (CH ₂ ) _b —C ₆ H ₅ . a is an integer of 0 to 7, and b is an integer of 0 to 4. R ² represents — (CH ₂ ) _c —. c is an integer of 2-4. x is an integer of 1-6.
R ¹ and R ³ are each preferably — (CH ₂ ) _a —CH ₃ , each a is preferably 2 to 4, and more preferably 2. C is preferably 2 to 3, and more preferably 2.

The polyether ester can be produced according to a known method, but can also be obtained as a commercial product.
Examples of such commercially available products include Adekasizer (ADK-CIZER: RS-966) (weight average molecular weight 470), Adekasizer RS-700 (weight average molecular weight 550), and Adekasizer RS-1000 (weight average molecular weight). 550) (manufactured by ADEKA Corporation).

The adipic acid ester is preferably a compound having a weight average molecular weight of 200 to 3,000 represented by the following formula (4) or (5), and either one may be used or both may be used in combination.

In formula (4), R ⁴ and R ⁵ each independently represent — (CH ₂ ) _d — (CR ⁶ R ⁷ ) _e — (CH ₂ ) _f —CH ₃ . Here, R ⁶ and R ⁷ each independently represent a hydrogen atom or — (CH ₂ ) _g —CH ₃ . D is an integer of 0 to 4, e is an integer of 0 to 2, f is an integer of 0 to 4, and g is an integer of 0 to 3.
R ⁶ is — (CH ₂ ) _g —CH ₃ , and R ⁷ is preferably a hydrogen atom. D is 1 to 3, e is 0 to 1, f is 1 to 3, and g is preferably 1 to 2. Further, d is 1, e is 1, f is 3, and g is more preferably 1.

In formula (5), R ⁸ and R ⁹ each independently represent — (CH ₂ ) _h — (CR ¹¹ R ¹² ) _i — (CH ₂ ) _j —CH ₃ . Here, R ¹¹ and R ¹² each independently represent a hydrogen atom or — (CH ₂ ) _k —CH ₃ . H is an integer of 0 to 4, i is an integer of 0 to 2, j is an integer of 0 to 4, and k is an integer of 0 to 3. R ¹⁰ represents — (CH ₂ ) ₁ —. l is an integer of 2-4. y is an integer of 1 to 4, and z is an integer of 1 to 4.
R ¹¹ is — (CH ₂ ) _k —CH ₃ , and R ¹² is preferably a hydrogen atom. H is preferably 1 to 3, i is 0 to 1, j is 1 to 3, and k is preferably 1 to 2. Moreover, it is preferable that l is 2-3. Furthermore, h is 1, i is 1, j is 3, k is 1, and 1 is more preferably 2.

Although adipic acid ester can be manufactured in accordance with a well-known method, it can also be obtained as a commercial item.
Examples of such commercially available products include Adeka Sizer RS-107 (weight average molecular weight 434) and Adeka Sizer P-200 (weight average molecular weight 2000) (manufactured by ADEKA Corporation).

  The copper paste composition of the present invention preferably consists essentially of (A) to (F), but as long as necessary, in addition to (A) to (F), as long as the effects of the present invention are not impaired. Various known additives such as a leveling agent, a viscosity modifier, a dispersant, a curing agent, and a foaming agent can be appropriately contained. Moreover, the thing containing the impurity which can be mixed unavoidable from the raw material component and the apparatus of the manufacturing process is also within the scope of the present invention.

<Method for producing surface-coated copper particles (A)>
Next, the manufacturing method (A) of the present invention will be described.
(A) can be produced by a method having the following steps 1 to 5. Preferably, a pretreatment step described below is performed before step 1. Since the copper particles may have impurities such as copper salts, dispersants, and copper oxides derived from their production attached to the surface, it is preferable to remove these impurities before step 1. This is because the dispersibility of the copper particles in a highly polar solvent such as water can be improved, and the coverage of the amine compound and the aliphatic monocarboxylic acid on the surface of the copper particles can be improved.

[Pretreatment process]
The method is not particularly limited as long as the impurities can be removed from the surface of the copper particles. For example, there is a cleaning method using an organic solvent or an acid. There are no particular restrictions on the type of organic solvent, but those having good wettability to the surface of the copper particles and easy to remove after the washing treatment may be used alone or in combination. Specific examples include alcohols, ketones, hydrocarbons, ethers, nitriles, isobutyronitriles, water, and 1-methyl-2-pyrrolidone. As the acid, an organic acid or an inorganic acid can be preferably used. Examples of the organic acid include acetic acid, glycine, alanine, citric acid, malic acid, maleic acid, malonic acid and the like. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, hydrogen bromide, phosphoric acid and the like. As a density | concentration of an acid, 0.1-50 mass% is preferable, and in order to suppress the heat of reaction, 0.1-10 mass% is more preferable. If it is less than 0.1% by mass, the removal of impurities may be insufficient, and if it exceeds 50% by mass, there is no difference in effect, and the impurity removal cost may increase.
In addition, when the washing process by an acid is implemented, in order to prevent the residue of the acid to the copper particle surface, it is preferable to wash | clean further with water or an organic solvent after acid washing.

[Step 1]
Step 1 is a step of coating the surface of the copper particles with the amine compound represented by the formula (1).

[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]
Specifically, the copper particle surface is obtained by adding pretreated copper particles or non-pretreated copper particles to a mixture a in an amine compound solution containing an amine compound, and stirring the mixture a. To form a first coating layer of the amine compound. The stirring method is not particularly limited, and stirring may be performed so that the copper particles and the amine compound are in sufficient contact, and a general stirring method may be used using a known stirrer such as a paddle stirrer or a line mixer.

Ideally, it is desirable to form a first coating layer in which the surface of the copper particles is uniformly coated with a monomolecular film of an amine compound, and it is preferable to form a good first coating layer as close to ideal as possible. . Therefore, the mixing ratio of the copper particles and the amine compound in step 1 is preferably a ratio suitable for forming this good first coating layer.
Specifically, although depending on the particle diameter of the copper particles, 0.1 to 200 parts by mass is preferable with respect to 100 parts by mass of the copper particles. 1-100 mass parts is more preferable at the point which suppresses that a free amine compound remains in surface-coated copper particles. Since the surface area per unit mass increases as the particle diameter of the copper particles decreases, it is preferable to increase the mixing amount of the amine compound as the particle diameter decreases.

  The solvent for preparing the amine compound solution is not particularly limited as long as the amine compound dissolves, has good wettability with the copper particles, and does not react with the amine compound and the aliphatic monocarboxylic acid. Preferably, it is a solvent containing at least one selected from alcohols, ketones, ethers, nitriles, sulfoxides, pyrrolidones, and water. Specifically, alcohols include methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, 1-pentanol, tert-amyl alcohol, ethylene glycol, butoxyethanol, methoxyethanol, ethoxyethanol, Examples include propylene glycol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether. Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of ethers include diethyl ether and dibutyl ether. Examples of nitriles include acetonitrile, propionitrile, butyronitrile, and isobutyronitrile. Examples of the sulfoxides include dimethyl sulfoxide. Examples of pyrrolidones include 1-methyl-2-pyrrolidone.

The treatment temperature for forming the first coating layer may be at or above the temperature at which the coating of the amine compound proceeds and the solution does not solidify, and is preferably a temperature at which the promotion of copper oxidation is low. Specifically, it is preferably performed in the range of −10 to 120 ° C. It is more preferable to carry out in the range of 30 to 100 ° C. in that the coating speed can be further increased and oxidation promotion can be further suppressed.
The treatment time is not particularly limited, but is preferably 5 minutes to 10 hours. Moreover, 5 minutes-3 hours are more preferable at the point of manufacturing cost. If it is less than 5 minutes, the coating with the amine compound may be insufficient. If it exceeds 10 hours, the amine compound forms a salt with carbon dioxide mixed in from the atmosphere, and the surface-coated copper particles May remain as an impurity.

  In addition, the step 1 is preferably performed in an inert gas atmosphere in that it is possible to suppress salt formation between an amine compound and carbon dioxide in the atmosphere and oxidation of copper. For example, bubbling of an inert gas or the like is performed. Preferably it is done. Specific examples of the inert gas include nitrogen, argon, helium and the like. The bubbling may also be used for stirring, that is, if the copper particles and the amine compound can be sufficiently contacted only by bubbling with an inert gas, stirring is not particularly required.

[Step 2]
Step 2 is a step in which an amine compound solution containing a free amine compound that has not been used for forming the first coating layer is removed from the mixture a to obtain an intermediate 1 containing the first coating layer-forming copper particles. . That is, it is a step of removing excess amine compound solution. At this time, it is not necessary to completely remove the excess amine compound, and the intermediate 1 can be obtained by natural sedimentation, separation by centrifugation, or filtration. That is, the intermediate 1 contains a small amount of a free amine compound and a solvent, but may proceed to the next step 3 as it is. In view of simple operation, a method of removing the supernatant amine compound solution by decantation or suction by an aspirator after the copper particles having the first coating layer formed by sedimentation by natural sedimentation is preferable.
In addition, the separated precipitate or filtrate may be washed with a solvent capable of dissolving both the amine compound and the aliphatic monocarboxylic acid having 8 to 20 carbon atoms to obtain the intermediate 1. This washing is preferable because the amount of free amine compound can be reduced. However, washing with water is not preferable because the amine compound forming the first coating layer may be detached.
The intermediate 1 may be dried to reduce the content solvent (the solvent of the amine compound solution), but drying at this stage may oxidize the copper surface, so drying, particularly heat drying, is performed. It is preferable not to.

If a large amount of free amine compound remains in the intermediate 1, impurities generated by the amine compound forming a salt with atmospheric carbon dioxide or an aliphatic monocarboxylic acid adversely affect the conductivity of the copper paste composition. Therefore, it is not preferable.
Therefore, the amount of the amine compound in the intermediate 1 is preferably 10% by mass or less of the amount of copper particles as the total amount of the amine compound and the free amine compound forming the first coating layer. In view of not affecting the formation of the second coating layer of the aliphatic monocarboxylic acid, the content is more preferably 1.0% by mass or less. The amount of amine compound in intermediate 1 can be determined from the difference from the amount of amine compound used in step 1 by measuring the amount of amine compound such as supernatant.

[Step 3]
Step 3 is a step of forming a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms on the first coating layer.
Specifically, an aliphatic monocarboxylic acid solution containing an aliphatic monocarboxylic acid having 8 to 20 carbon atoms is added to the intermediate 1 to obtain a mixture b, and the mixture b is agitated, whereby the first coating layer is formed. To form a second coating layer of an aliphatic monocarboxylic acid. The intermediate 1 may be added to an aliphatic monocarboxylic acid solution containing an aliphatic monocarboxylic acid having 8 to 20 carbon atoms to form a mixture b. The stirring method is not particularly limited, and the stirring may be performed so that the copper particles on which the first coating layer is formed and the aliphatic monocarboxylic acid are in sufficient contact with each other, using a known stirrer such as a paddle stirrer or a line mixer. A general stirring method may be used.

Ideally, a second coating layer in which the first coating layer is uniformly coated with an aliphatic monocarboxylic acid in the form of a monomolecular film is formed by the bond between the amine compound of the first coating layer and the aliphatic monocarboxylic acid. It is desirable that a good second coating layer as close to ideal as possible be formed. Accordingly, the mixing ratio of the copper particles and the aliphatic monocarboxylic acid in step 3 is preferably a ratio suitable for forming this good second coating layer.
Specifically, although depending on the particle diameter of the copper particles, 0.1 to 50 parts by mass is preferable with respect to 100 parts by mass of the copper particles. 0.5-10 mass parts is more preferable at the point which suppresses that a free aliphatic monocarboxylic acid remains in surface-coated copper particles. Since the surface area per unit mass increases as the particle size of the copper particles decreases, it is preferable to increase the amount of the aliphatic monocarboxylic acid mixed as the particle size decreases.

The solvent for preparing the aliphatic monocarboxylic acid solution having 8 to 20 carbon atoms is good in wettability with the copper particles in which the aliphatic monocarboxylic acid is dissolved and the copper particles and the first coating layer are formed. And it will not be specifically limited if it does not react with aliphatic monocarboxylic acid. Any solvent that can be easily removed by drying in the drying step of Step 5 described later is preferable.
A preferable solvent is a solvent containing at least one selected from alcohols, ketones, ethers, nitriles, sulfoxides, and pyrrolidones. Specifically, alcohols are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, tert-amyl alcohol, ethylene glycol, butoxyethanol, methoxyethanol, ethoxyethanol. , Propylene glycol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether. Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of ethers include diethyl ether and dibutyl ether. Nitriles include acetonitrile, propionitrile, butyronitrile and isobutyronitrile. Examples of the sulfoxides include dimethyl sulfoxide. Examples of pyrrolidones include 1-methyl-2-pyrrolidone.

The treatment temperature for forming the second coating layer may be at or above the temperature at which the coating of the aliphatic monocarboxylic acid proceeds and the solution does not solidify. Specifically, the treatment temperature is in the range of −10 to 80 ° C. Is preferred. It is more preferable to carry out in the range of 10 to 60 ° C. in terms of further increasing the coating speed and suppressing the elimination of the aliphatic monocarboxylic acid that has formed the second coating layer.
The treatment time is not particularly limited, but is preferably 5 minutes to 10 hours. Moreover, 5 minutes-3 hours are more preferable at the point of manufacturing cost. If it is less than 5 minutes, the coating with the aliphatic monocarboxylic acid may be insufficient, and if it exceeds 10 hours, the component released as a copper-amine compound-fatty acid complex remains in the surface-coated copper particles. This is not preferable because it may adversely affect the conductivity of the copper paste composition.

  In addition, the step 3 is also an inert gas atmosphere in that the salt formation between the amine compound of the first coating layer and the free amine compound mixed in a small amount and carbon dioxide in the atmosphere can be suppressed and copper oxidation can be suppressed. For example, it is preferable to perform bubbling of an inert gas. Specific examples of the inert gas include nitrogen, argon, helium and the like. Further, the bubbling may also be used for stirring, that is, if the copper particles on which the first coating layer is formed and the aliphatic monocarboxylic acid can be sufficiently contacted only by bubbling with an inert gas, In particular, stirring may not be performed.

[Step 4]
Step 4 removes the aliphatic monocarboxylic acid solution containing the free aliphatic monocarboxylic acid that was not used to form the second coating layer from the mixture b, and contains the first and second coating layer-forming copper particles. This is a step of obtaining the intermediate 2 to be Specifically, the intermediate 2 can be obtained by filtration. As a filtration method, a known method can be applied, and natural filtration, vacuum filtration, pressure filtration, and the like can be exemplified. In addition, in order to remove free aliphatic monocarboxylic acid and free amine compound as much as possible, the filtrate is washed with a solvent that can dissolve both the aliphatic monocarboxylic acid having 8 to 20 carbon atoms and the amine compound. Thus, the intermediate 2 is preferable. By reducing the amount of free aliphatic monocarboxylic acid by washing, the adhesiveness of the composition to the substrate when a copper paste composition is obtained is improved.

[Step 5]
Step 5 is a step of drying the intermediate 2 to obtain the surface-coated copper particles (A) of the present invention.
The drying method is not particularly limited, and examples thereof include reduced-pressure drying and freeze-drying. Vacuum drying is preferable from the viewpoint of production cost, and the drying temperature is preferably 20 to 120 ° C. If it is less than 20 ° C., the drying time may be long, and if it is higher than 120 ° C., copper may be oxidized. The degree of vacuum, the drying temperature, and the drying time may be appropriately determined depending on the combination of the respective conditions and the type of the solvent used, and so on until the amount of the solvent in the surface-coated copper particles after drying becomes 1 mass% or less. Any conditions that can be dried are preferred.
The surface-coated copper particles (A) can be produced by the above production method.

<Method for producing copper paste composition>
The copper paste composition of the present invention can be produced by mixing (A) to (F) and optionally other additives using a kneading (mixing) device. As the kneading apparatus, a three-roll kneader can be used. The kneading temperature is in the range of 10 to 60 ° C., and the number of kneading may be any condition as long as the particles can be uniformly dispersed in the paste. The order of addition (mixing) of (A) to (F) may be any order, and may be added together and kneaded and mixed.

<Method of forming a cured copper film>
A copper paste film can be formed by applying the copper paste composition onto a substrate by screen printing and heating at 100 ° C. to 200 ° C. for 10 to 120 minutes. Heating can be performed using a drying oven, a hot plate, an IR baking apparatus, a light baking apparatus, or the like. In the cured copper film, heating is performed under the conditions that (B) and (C) are sufficiently cured by heat and thermally cured, and the solvent (E) is removed by drying.

Hereinafter, the embodiments of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
The copper particles used in each of the examples and comparative examples, and the methods for treating, measuring, processing, and evaluating the copper particles are shown below.

<Copper particles>
Copper particles: 1400 YP (average particle diameter D50; 5.8 μm, average thickness of particles; 1.1 μm, D50 / average thickness; 5.3, manufactured by Mitsui Mining & Smelting Co., Ltd.).

<Pretreatment of copper particles>
The pretreatment of the copper particles was performed by the following method.
220 g of copper particles were put into a mixed solution of 352 g of toluene and 88 g of isopropanol, and refluxed at 70 ° C. for 30 minutes while being stirred and dispersed. After refluxing, toluene and isopropanol were removed from the copper particle-containing mixture by vacuum filtration. The filtered copper particles were put into 440 g of 3.5% hydrochloric acid aqueous solution and stirred at 30 ° C. for 30 minutes. After stirring, the aqueous hydrochloric acid solution was removed from the aqueous hydrochloric acid solution containing copper particles by filtration under reduced pressure. Subsequently, the filtered copper particles were put into 440 g of isopropanol and stirred at 30 ° C. for 15 minutes. After stirring, isopropanol was removed from the copper particle-containing isopropanol by filtration under reduced pressure, and the filtered copper particles were dried under reduced pressure at 25 ° C. for 12 hours to obtain pretreated copper particles.
The filtration under reduced pressure was performed by reducing the pressure of the 5C filter paper Kiriyama funnel with a diaphragm pump. Further, the drying under reduced pressure was performed by putting the filtered copper particles in a vacuum oven and reducing the pressure of the oven with an oil pump.

<Production of surface-coated copper particles (A)>
[Step 1]
200 g of the pretreated copper particles were put into 600 g of water, and nitrogen bubbling was performed for 30 minutes while stirring at 25 ° C. After heating up this copper particle containing water to 60 degreeC, 400 g of 50 mass% ethylenediamine aqueous solution was dripped at the said copper particle containing water at 30 mL / min, and it stirred for 40 minutes, hold | maintaining 60 degreeC. Stirring was performed using a mechanical stirrer at a rotation speed of 150 rpm. Hereinafter, stirring was performed at the same rotational speed using the same stirring device.
[Step 2]
Stirring was stopped and the mixture was allowed to stand for 5 minutes, and then about 800 g of the supernatant was extracted and removed. Subsequently, 800 g of isopropanol was added as a washing solvent to the precipitate, and the mixture was stirred at 30 ° C. for 3 minutes. Stirring was stopped and the mixture was allowed to stand for 5 minutes, and then about 800 g of the supernatant was extracted and removed to obtain Intermediate 1.
[Step 3]
After adding 1000 g of an isopropanol solution of 2% by mass myristic acid to Intermediate 1, the mixture was stirred at 30 ° C. for 30 minutes.
[Step 4]
After stopping the stirring, the isopropanol solution of myristic acid was removed by filtration under reduced pressure to obtain Intermediate 2. The vacuum filtration was performed by reducing the pressure of the 5C filter paper Kiriyama funnel with a diaphragm pump.
[Step 5]
Surface-coated copper particles (A) were obtained by drying Intermediate 2 under reduced pressure at 25 ° C. for 3 hours. The drying under reduced pressure was performed by placing the intermediate 2 in a vacuum oven and reducing the pressure of the oven with an oil pump.

<Infrared absorption (IR) spectrum analysis>
Measuring instrument model: FT / IR-6100 manufactured by JASCO Corporation
Measuring method: ATR method, decomposition; 2 cm ⁻¹ , number of integrations: 80 times The obtained IR spectrum of the surface of (A) was measured by the above method using the above measuring device. The IR spectrum of (A) is shown in FIG.
When ethylenediamine used for coating is measured alone in the same manner, the peak of N—H bending vibration appears at 1598 cm ⁻¹ (FIG. 2), whereas it is observed in the surface-coated copper particles (A). The peak of N—H bending vibration is shifted to the low wavenumber side of 1576 cm ⁻¹ , indicating that ethylenediamine is coordinated and present on the copper particle surface. In FIG. 1, the peak of C═O stretching vibration of myristic acid is not observed at 1700 cm ^−1, and the peak of carboxylate anion (—COO ⁻ ) is observed near 1400 cm ⁻¹ , and myristic acid is an amine. It shows that the compound exists by electrostatic interaction.
From the IR spectrum, it can be determined that both the ethylenediamine of the first coating layer and the myristic acid of the second coating layer are bonded by chemical bonds to form each coating layer.

<Resol type phenol resin (B)>
As (B), PL-5208 (58.5 mass% diethylene glycol monoethyl ether solution of (B), manufactured by Gunei Chemical Industry Co., Ltd.) as a solution containing (B) was used. Diethylene glycol monoethyl ether as a solvent was a part of the solvent (E).

<Vinylphenol polymer (C)>
As (C), the following three types of (C1) to (C3) -containing solutions were used. In either case, diethylene glycol monomethyl ether acetate as a solvent was a part of the solvent (E).
(C1): Vinylphenol homopolymer (weight average molecular weight 9,500) [Marcalinker S-4P; 50.0 mass% diethylene glycol monomethyl ether acetate solution of (C1), manufactured by Maruzen Petrochemical Co., Ltd.]
(C2): Vinylphenol homopolymer (weight average molecular weight 2,000) [Marcalinker S-1; 50.0 mass% diethylene glycol monomethyl ether acetate solution of (C2), manufactured by Maruzen Petrochemical Co., Ltd.]
(C3): copolymer of 55 mol% vinylphenol and 45 mol% methyl methacrylate (weight average molecular weight 10,000) [Marcalinker CMM; (C3) 50.0 mass% diethylene glycol monomethyl ether acetate solution, manufactured by Maruzen Petrochemical Co., Ltd. ]

<Chelating agent (D)>
The following two types were used as (D).
(D1): 1,4-phenylenediamine (D2): N, N′-bis (salicylidene) -1,2-propanediamine

<Solvent (E)>
The following two types were used as (E).
(E1): Diethylene glycol monoethyl ether [solvent of (B)]
(E2): Diethylene glycol monomethyl ether acetate [including those used as a solvent for (C). ]

<Flexibility imparting agent (F)>
The following four types were used as (F).
(F1): Tris phosphate (2-ethylhexyl)
(F2): Bis (2-ethylhexyl) phthalate
(F3): Adeka Sizer RS-1000 (polyether ester, weight average molecular weight 550, manufactured by ADEKA Corporation)
(F4): Adeka Sizer P-200 (Adipic acid polyester, weight average molecular weight 2000, manufactured by ADEKA Corporation)

Example 1
<Manufacture of copper paste composition>
(A) 100 g, 25.6 g of a diethylene glycol monoethyl ether solution of (B) [(B); 15.0 g, (E1); 10.6 g], 2.0 g of a diethylene glycol monomethyl ether acetate solution of (C1) [(C1 ); 1.0 g, (E2); 1.0 g], (D1) 1.0 g, and (F1) 2.0 g. Next, using a planetary mixer [ARV-310, manufactured by Shinkey Co., Ltd.], the mixture was stirred at room temperature for 30 seconds at a rotation speed of 1500 rpm to perform primary kneading.
Next, secondary kneading was performed using a three-roll mill [EXAKT-M80S, manufactured by Nagase Screen Printing Laboratory Co., Ltd.] five times under conditions of room temperature and a distance between rolls of 5 μm.
Next, 3.9 g of (E2) was added to the kneaded material obtained by the secondary kneading, and the mixture was defoamed and kneaded by stirring for 90 seconds at a rotation speed of 1000 rpm under a room temperature and vacuum condition using a planetary mixer. A paste composition was produced.
Moreover, the compounding ratio of each component in the copper paste composition is shown in Table 1.

<Formation of cured copper film>
A pattern of width × length × thickness = 1.0 mm × 30 mm × 30 μm was applied to the obtained copper paste composition on a paper substrate using a metal mask. A paper substrate coated with the copper paste composition was heated in a convection oven at 150 ° C. for 30 minutes to prepare a cured copper film.

<Electrical conductivity evaluation>
The conductivity of the obtained copper cured film was evaluated by the following surface resistance measurement.
A resistance measurement probe was pressed against both ends of the copper cured film pattern, and the surface resistance value of the copper wiring was measured using a digital multimeter. The lower the surface resistance value, the easier the current flows, that is, the higher the conductivity.
The measuring instrument model and measurement conditions are shown below.
Measuring instrument model: Digital multimeter PC7000 [manufactured by Sanwa Denki Keiki Co., Ltd.]
Measurement conditions: Two-terminal method

<Evaluation of disconnection resistance>
The resistance to disconnection of the cured copper film in a high-temperature and high-humidity environment was determined by changing the conductivity (the surface resistance value) before and after exposure to the environment and evaluating the appearance.
(Evaluation of conductivity change)
A high-temperature, high-humidity environment is obtained by storing a copper cured film sample on a paper substrate in an environment tester ENVIROS KCL-1000 (manufactured by Tokyo Rika Kikai Co., Ltd.) in an environment of 85 ° C. and 85% RH for 168 hours. It was set as the sample after exposure. The surface resistance value after the exposure was measured in the same manner as described above, and the change rate of the measured value before and after the exposure was determined by the following formula (I).
Surface resistance value change rate (%)
= [(Surface resistance value after exposure to high temperature and high humidity environment) / (Surface resistance value before exposure to high temperature and high humidity environment)]
× 100 (I)
The smaller the value of the surface resistance value change rate, the smaller the change in conductivity in a high temperature and high humidity environment, and the higher the resistance to disconnection. The results are shown in Table 1. In Table 1, the surface resistance value 1 indicates the surface resistance value before exposure to a high temperature and high humidity environment, and the surface resistance value 2 indicates the surface resistance value after exposure to a high temperature and high humidity environment.
(Appearance evaluation)
The disconnection of the copper cured film after exposure to a high temperature and high humidity environment was evaluated by appearance observation. The evaluation criteria are shown below. The evaluation results are shown in Table 1. Moreover, the external appearance observation result after high temperature high humidity environment exposure of a copper cured film is shown in FIG.
○: The occurrence of cracks was not confirmed.
X: Generation | occurrence | production of the crack was confirmed.

(Examples 2-9), (Comparative Examples 1-4)
A copper paste composition was produced and a copper cured film was formed in the same manner as in Example 1 except that the blending ratio of each component was as shown in Table 1.
In Comparative Example 2, the following fluoroelastomer (X) was used instead of (C).
(X): Fluoroelastomer (copolymer of vinylidene fluoride and propylene hexafluoride) [DAIEL (DAI_EL: registered trademark) G-801; (X) 50.0 mass% diethylene glycol monomethyl ether acetate solution, Daikin Industries Ltd. Made by company]
Furthermore, each copper cured film was evaluated in the same manner as in Example 1 for conductivity and disconnection resistance. The results are shown in Table 1. Moreover, the external appearance observation result after the high temperature high humidity environment exposure of the copper cured film of the comparative example 1 is shown in FIG.

In Examples 1 to 9, the surface resistance value of the copper cured film before exposure to high temperature and high humidity environment is 1.0Ω or less, and the increase rate of the surface resistance value before and after exposure to high temperature and high humidity environment is suppressed to 200% or less. Is done.
On the other hand, in the case of Comparative Example 1 of the copper paste composition using only the resol type phenolic resin (B) as a binder, the surface resistance value of the cured copper film before exposure to a high temperature and high humidity environment is 1.0Ω or less, but the high temperature The change rate of the surface resistance value before and after exposure to a high humidity environment was as large as 400% or more, and cracks were observed in appearance evaluation. The reason for this is that the resol-type phenolic resin used for the binder promotes contact between the particles by shrinkage during curing, and has reducibility, so it is easy to ensure conductivity. Since a strong network is formed by three-dimensional crosslinking and the flexibility is poor, the deformation of the copper cured film cannot follow the dimensional change due to moisture absorption of the paper substrate, and cracks are generated, maintaining the conductivity. It is thought that it was not possible.
Moreover, although the comparative example 2 is a copper paste composition manufactured using the fluorine elastomer (X) instead of the polyvinylphenol polymer (C), the increase rate of the surface resistance value before and after exposure to a high temperature and high humidity environment is 200. %, It was relatively good in terms of wire breakage resistance. However, the surface resistance value of the copper cured film before exposure to a high temperature and high humidity environment was high, and the conductivity was poor. This is because the fluoroelastomer does not have a hydroxyl group unlike polyvinylphenol and does not have a crosslinking point with the resol type phenol resin, so that each component is separated in the binder and the copper in the copper cured film is separated. This is probably because the conductive path could not be formed by inhibiting the dispersion of the particles. However, the elastomer component is effective in terms of flexibility, and it is considered that the occurrence of disconnection is suppressed.
Comparative Examples 3 and 4 are compositions outside the upper limit or lower limit of the blending amount of each component, but these have poor dispersibility of each component in the cured copper film, so that good conductivity and resistance to disconnection are obtained. It is thought that it was not possible.

Claims (5)

Contains surface-coated copper particles (A), resol type phenolic resin (B), vinylphenol polymer (C), chelating agent (D), solvent (E), and flexibility imparting agent (F),
The surface-coated copper particles (A) include a first coating layer of an amine compound represented by the formula (1) that is bonded to copper on the surface of the copper particles by a chemical bond and / or a physical bond, and the first coating. A second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms bonded to the amine compound by a chemical bond on the layer;
10-100 parts by mass of the resol type phenol resin (B), 0.5-3.0 parts by mass of the vinylphenol polymer (C), 100 parts by mass of the surface-coated copper particles (A) Containing 0.5 to 3.0 parts by mass of the agent (D), 10 to 40 parts by mass of the solvent (E), and 0.5 to 3.0 parts by mass of the flexibility-imparting agent (F).
Copper paste composition.

[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ] The vinylphenol polymer (C) is a homopolymer of vinylphenol and a copolymer of vinylphenol and one or more monomers selected from styrene, butyl acrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate. At least one polymer selected from the group consisting of:
The polymer has a structural unit represented by the formula (2) and has a weight average molecular weight of 1,000 to 20,000.
The copper paste composition according to claim 1.
The chelating agent (D) is at least one compound selected from aromatic diamines and Schiff bases.
The copper paste composition according to claim 1 or 2. The flexibility imparting agent (F) is at least one compound selected from phosphoric acid esters, phthalic acid esters, polyether esters, and adipic acid esters.
The copper paste composition as described in any one of Claims 1-3. The flexibility imparting agent (F) is a polyether ester having a weight average molecular weight of 450 to 650 represented by the formula (3), and a weight average molecular weight of 200 to 200 represented by the formulas (4) and / or (5). At least one compound selected from 3,000 adipic acid esters,
The copper paste composition according to claim 4.

Wherein (3), ^{R 1} and ^{R 3} are each _{independently, - (CH 2) a -CH} 3, or _- represents a _{(CH 2) b -C 6 H} 5. a is an integer of 0 to 7, and b is an integer of 0 to 4. R ² represents — (CH ₂ ) _c —. c is an integer of 2-4. x is an integer of 1-6. ]

[In Formula (4), R ⁴ and R ⁵ each independently represent — (CH ₂ ) _d — (CR ⁶ R ⁷ ) _e — (CH ₂ ) _f —CH ₃ . Here, R ⁶ and R ⁷ each independently represent a hydrogen atom or — (CH ₂ ) _g —CH ₃ . D is an integer of 0 to 4, e is an integer of 0 to 2, f is an integer of 0 to 4, and g is an integer of 0 to 3. ]

Wherein (5), ^{R 8} and ^{R 9} each independently represents - _{(CH 2) j -CH 3 -} (CH 2) h - (CR 11 R 12) i. Here, R ¹¹ and R ¹² each independently represent a hydrogen atom or — (CH ₂ ) _k —CH ₃ . H is an integer of 0 to 4, i is an integer of 0 to 2, j is an integer of 0 to 4, and k is an integer of 0 to 3. R ¹⁰ represents — (CH ₂ ) ₁ —. l is an integer of 2-4. y is an integer of 1 to 4, and z is an integer of 1 to 4. ]