JP5651299B2 - Process for producing conductive molded product, conductive molded product, and silver paste used therefor - Google Patents

Description

  The present invention relates to a silver paste containing a polymer compound containing a polyethyleneimine skeleton, silver nanoparticles, and a specific additive, which can be sintered at a low temperature, and a low-temperature sintering type conductivity obtained by using the silver paste. The present invention relates to a molded product and a manufacturing method thereof.

  Metal nanoparticles are nanoparticles having a particle size of 1 to several hundred nanometers, and since their specific surface area is remarkably large, molded products using metal nanoparticles have attracted attention from many fields, such as catalysts, electronic materials, Applications to magnetic materials, optical materials, various sensors, color materials, medical examinations, etc. are expected. However, when the metal is reduced to a nano size, the surface energy increases, so that a melting point drop occurs on the particle surface. As a result, the metal nanoparticles tend to be fused with each other, resulting in poor storage stability. In order to stabilize the metal nanoparticles, it is necessary to protect them with a protective agent in order to prevent the fusion.

  The present inventors have already prepared a metal nanoparticle dispersion in which metal nanoparticles are contained in a dispersion formed by a polymer compound containing a polyalkyleneimine chain, a hydrophilic segment, and a hydrophobic segment in a solvent, and A method for producing a metal nanoparticle dispersion has been reported (for example, see Patent Document 1). The metal nanoparticle dispersion reduces the metal ion by the strong reducing ability, coordination bonding force and electrostatic interaction of the polyalkyleneimine chain in the polymer compound used, and the metal is incorporated into the dispersion as a nanoparticle. It is a dispersion formed by immobilization. Even if the morphology of the dispersion is changed due to the shrinkage of the polyalkyleneimine chain due to the unique function of the polyalkyleneimine chain, the hydrophilic segment and the hydrophobic segment in the polymer compound are It exhibits high self-organization ability due to its high affinity with and strong associative force due to the interaction between the segments, so it does not impair the dispersion stability as a dispersion and is stable in a solvent for a long time. The state is retained.

Moreover, it has also reported about the molded article using the metal nanoparticle dispersion mentioned above (for example, refer patent document 2). The molded product is obtained by using the metal nanoparticle dispersion as it is, and does not require complicated operation, but has insufficient electrical characteristics. For example, even if heat treatment is performed at 200 ° C. for 30 minutes, the resistance value is only 7.8 × 10 ⁻⁴ Ω · cm, which is two digits from the resistance value of bulk silver, 1.6 × 10 ⁻⁶ Ω · cm. In addition, the numerical value is high, and high-temperature treatment is required, and it is difficult to apply to a plastic substrate used for a flexible display or the like.

Examples of the conductive paste exhibiting high conductivity (low resistance value) by low-temperature firing at 200 ° C. or lower include, for example, an amine compound having 5 to 20 carbon atoms, an amide compound having 4 to 30 carbon atoms, and an aldehyde compound as a protective agent. In addition, there is provided a conductive ink composition obtained by using one kind selected from an ester compound and a ketone compound, and reducing the ions in a solution containing noble metal ions in the presence thereof (for example, (See Patent Document 3). According to the Patent Document 3, even by low temperature sintering of 80 to 150 ° C., it is described as a thin film of low resistivity can be obtained, in practice, firing 30 min at 80~100 ℃ 1 × 10 ^- The resistivity is not in the order of ⁶ Ω · cm, and in order to obtain a level that can be used as a conductive molded product, firing at 180 to 200 ° C. is still necessary. Moreover, in the said patent document 3, although a low molecular weight thing is selected as a protective agent to be used, and it tries to obtain a metal thin film by volatilizing these at the time of sintering, Originally, a noble metal etc. and a plastic substrate adhere closely Even if the metal thin film is obtained by sintering, the thin film may be peeled off from the substrate or cracked with the volatilization of the protective agent. In order to prevent this, it is necessary to treat the surface of the substrate and a third component such as an adhesive for imparting adhesion (for example, refer to Patent Document 4). At present, no material capable of forming a conductive film at a practical level has been found yet.

Japanese Patent Laid-Open No. 2006-213887 JP 2008-045024 A JP 2006-183072 A JP 2003-183616 A

  The problem to be solved by the present invention is to obtain a molded product obtained by adhering a structure containing a silver nanoparticle component and an organic component by a simple method and firing at a low temperature of 150 ° C. or lower. Also has a high conductivity and can be widely used in many fields of application such as electronic materials, magnetic materials, optical materials, various sensors, medical examinations, etc. It is to provide a silver paste which can be used at low temperature.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a silver nanoparticle dispersion obtained by using a compound containing a polyethyleneimine skeleton as a protective agent, and a functional group capable of reacting with a nitrogen atom in the polyethyleneimine. By applying a silver paste having a melting point in a specific range to a base material, a molded product having an arbitrary shape exhibiting high conductivity in low-temperature firing can be obtained without performing complicated processing or the like. The inventors have found that the present invention can be obtained and have completed the present invention.

That is, the present invention
(1) Compound (x1) formed by bonding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000,
Compound (x2) in which linear epoxy resin (c) is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and polyethyleneimine having a number average molecular weight of 500 to 50,000 Compound (x3) formed by binding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and linear epoxy resin (c) to the amino group in (a)
One or more compounds (X) selected from the group consisting of: silver nanoparticles (Y);
An aqueous dispersion of a silver-containing structure comprising as a main constituent;
A compound (Z) having a functional group capable of reacting with a nitrogen atom of polyethyleneimine (a) in the compound (X), and a silver paste having a melting point of 100 to 150 ° C. in a dry state as a solid substrate Applying on top,
(2) A step of drying the solid base material after applying the silver paste obtained in the step (1) at 25 ° C to 150 ° C,
It is intended to provide a method for producing a conductive molded product characterized by having a conductive molded product having an arbitrary shape obtained by the production method.

The present invention also relates to a compound (x1) obtained by bonding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000,
Compound (x2) in which linear epoxy resin (c) is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and polyethyleneimine having a number average molecular weight of 500 to 50,000 Compound (x3) formed by binding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and linear epoxy resin (c) to the amino group in (a)
An aqueous dispersion of a silver-containing structure comprising, as main components, one or more compounds (X) selected from the group consisting of: and silver nanoparticles (Y); and a polyethyleneimine in the compound (X) ( A silver paste comprising a compound (Z) having a functional group capable of reacting with a nitrogen atom of a) and having a melting point in a dry state of 100 to 150 ° C. is provided.

  The conductive molded product of the present invention is formed by forming a conductive film on a solid substrate, and the glass transition temperature of the solid substrate is insufficient for heat resistance of 180 ° C. or less. Of course, as the planar substrate, a rod-shaped, tube-shaped, fiber-shaped, or three-dimensional molded product subjected to fine processing can be used. Moreover, as the manufacturing method, the silver paste of this invention should just be apply | coated and dried, and since there is no limitation in particular in the application method, it can be used for various application fields. In addition, it has various chemical, electrical, magnetic, and optical performances due to the inclusion of metal nanoparticles such as large specific surface area, high surface energy, and plasmon absorption, and a wide range of fields. For example, it can be applied to catalysts, electronic materials, magnetic materials, optical materials, various sensors, color materials, medical examination applications, and the like.

Hereinafter, the present invention will be described in detail.
The method for producing a conductive molded product according to the present invention comprises: (1) polyethylene glycol (b) having a number average molecular weight of 500 to 50,000 and an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000; ) Are combined (x1),
Compound (x2) in which linear epoxy resin (c) is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and polyethyleneimine having a number average molecular weight of 500 to 50,000 Compound (x3) formed by binding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and linear epoxy resin (c) to the amino group in (a)
One or more compounds (X) selected from the group consisting of: silver nanoparticles (Y);
An aqueous dispersion of a silver-containing structure comprising as a main constituent;
A compound (Z) having a functional group capable of reacting with a nitrogen atom of polyethyleneimine (a) in the compound (X), and a silver paste having a melting point of 100 to 150 ° C. in a dry state as a solid substrate Applying on top,
(2) A step of drying the solid base material after the silver paste coating obtained in the step (1) at 25 ° C to 150 ° C.

  The silver nanoparticles (Y) in the present invention have an average particle diameter (100 particles randomly extracted and averaged) observed in a transmission electron micrograph of 100 nanometers or less. It does not require that the shape be a perfect sphere. Moreover, the number average molecular weight of each segment which comprises compound (X) is a polystyrene conversion value measured by gel permeation chromatography (GPC). Furthermore, the silver-containing structure having the compound (X) and the silver nanoparticles (Y) as main components is intentionally used in addition to impurities mixed in due to insufficient purification in the purification step. Unless it mix | blends the 3rd component of, it consists of the said compound (X) and silver nanoparticle (Y), and has a structure of a nanometer order. Even when an additive or the like is blended, the total mass ratio of the compound (X) and the silver nanoparticles (Y) in the silver-containing structure is 90% by mass or more. Furthermore, the melting point in the dry state refers to the melting point obtained by DSC measurement in a state where the solvent in the silver paste is volatilized and does not have fluidity.

  In the polyethyleneimine (a) constituting the compound (X) used in the present invention, the ethyleneimine unit in the chain can be coordinated with silver and its ions, and further promotes reduction of silver ions to form silver nanoparticles. (Y) is a polymer chain that stabilizes and holds the silver nanoparticles (Y). The structure has an ethyleneimine unit as the main repeating unit, and may be linear or branched, and may be either a commercial product or a synthetic product.

  The size of the silver-containing structure used in the present invention is not limited to the molecular weight of the compound (X) used, but also the components constituting the compound (X), that is, polyethyleneamine (a), polyethylene glycol (b), and It is also affected by the structure and composition ratio of the linear epoxy resin (c) and the type of silver compound used as a raw material. In the case of the polyethyleneimine (a) having the same molecular weight, if the degree of branching is small, the particle size of the resulting structure is large, and the particle size tends to decrease as the degree of branching is improved. Moreover, in order to raise the content rate of silver nanoparticle (Y), it is preferable to use branched polyethyleneimine.

  The commercially available branched polyethyleneimine is branched by a tertiary amine and can be used as a raw material for the compound (X) used in the present invention. From the standpoint of obtaining an aqueous dispersion of a silver-containing structure having an excellent storage stability and a preferable particle size, the degree of branching is expressed by a molar ratio of (tertiary amine) / (all amines) (1 to 49). The branching degree is preferably in the range of / (100), and the more preferable range of branching degree is (15 to 40) / (100) in view of industrial production, availability and the like.

  When the number average molecular weight of the polyethyleneimine (a) moiety is too low, the retention ability of the silver nanoparticles (Y) by the compound (X) tends to be lowered, and the storage stability may be insufficient. If the amount is too large, the compound (X) becomes a huge aggregate, which may hinder the storage stability of the dispersion. Therefore, an aqueous dispersion of a silver-containing structure having a superior ability to immobilize silver nanoparticles (Y) in the aqueous dispersion of the resulting silver-containing structure and the ability to prevent the dispersion from becoming too large is obtained. In order to obtain it, it is essential that the polyethyleneimine (a) has a number average molecular weight in the range of 500 to 50,000, preferably in the range of 1,000 to 40,000, Most preferably, it is in the range of 30,000.

  The polyethylene glycol (b) constituting the compound (x1) and the compound (x3) used in the present invention promotes dispersion stabilization in a hydrophilic solvent as a hydrophilic segment. When the molecular weight of the polyethylene glycol (b) is dispersed in a hydrophilic solvent, the dispersion stability may be deteriorated if the molecular weight is too low, and the structures may be aggregated if the molecular weight is too high. Therefore, in order to obtain an aqueous dispersion of a silver-containing structure with better storage stability, the polyethylene glycol (b) must have a number average molecular weight in the range of 500 to 5,000, It is preferable that it is 000-3,000.

  The polyethylene glycol (b) may be a commercially available product or a synthetic product. Further, it may be a copolymer with other hydrophilic polymer. Examples of the hydrophilic polymer that can be used at this time include polyvinyl alcohol, polyacrylamide, polyisopropylacrylamide, and polyvinylpyrrolidone. From the viewpoint of increasing the silver content of the resulting silver-containing structure, even when a copolymer is used, the overall molecular weight is preferably in the range of 500 to 5,000.

  In the compound (x2) and the compound (x3) used in the present invention, a linear epoxy resin (c) is bonded as a hydrophobic segment. In the case where the compound (x2) and the compound (x3) are dispersed in water or a hydrophilic solvent by containing the structure derived from the linear epoxy resin (c) in the compound (x2) and the compound (x3) The strong association force between molecules or between molecules forms a micelle core, forms a stable micelle, and incorporates silver nanoparticles (Y) therein, thereby obtaining a stable dispersion.

  The linear epoxy resin (c) can be used without particular limitation as long as it is generally commercially available or can be synthesized. Examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, xanthene type epoxy resin described in JP-A No. 2003-201333, and the like. The above may be mixed. Among these, when the obtained silver-containing dispersion is used as a silver paste, it is preferable to use a bisphenol A type epoxy resin from the viewpoint of excellent adhesion to the substrate. These linear epoxy resins may be used as raw materials for the compound (x2) or the compound (x3) as they are, and various modifications may be made depending on the structure of the target compound (x2) or the compound (x3). May be added.

  In addition, the molecular weight of the linear epoxy resin (c) is not particularly limited, but when dispersed in a hydrophilic organic solvent, dispersion stability is deteriorated if it is too low, and micelles are formed if it is too high. There is a possibility of aggregation. From these viewpoints, the number average molecular weight of the linear epoxy resin (c) is usually 350 to 20,000, and preferably 400 to 10,000.

  Although it does not specifically limit as a manufacturing method of compound (X) used by this invention, The thing by the following method is preferable from the point which can synthesize | combine the compound as designed easily.

  As described above, a commercially available or synthesized polyethyleneimine (a) can be suitably used. First, a case where branched polyethyleneimine is used will be described.

  Since the terminal of the branched polyethyleneimine is a primary amine, the terminal of polyethylene glycol (b) can be used in the present invention by pre-modifying and reacting with a functional group that reacts with the primary amine. Compound (x1) can be synthesized. The functional group that reacts with the primary amine is not particularly limited. For example, aldehyde group, carboxy group, isocyanate group, tosyl group, epoxy group, glycidyl group, isothiocyanate group, halogen, acid chloride, sulfonic acid Examples include chloride. Among them, a carboxy group, an isocyanate group, a tosyl group, an epoxy group, and a glycidyl group are advantageous in terms of production, such as reactivity and ease of handling, and are preferred functional groups.

  In addition, the functional group may not be a functional group that directly reacts with the primary amine, but may be any functional group that can be reacted with the primary amine by performing various treatments. For example, polyethylene glycol having a hydroxy group may be used. For example, it may be reacted with polyethyleneimine by a method such as glycidylation. Furthermore, the compound (x1) may be synthesized by applying a treatment to convert the primary amine of the branched polyethyleneimine into another functional group capable of reacting with a functional polyethylene glycol and then reacting them. Is possible.

  When the polyethyleneimine (a) is a linear polyethyleneimine, first a polyacylated ethyleneimine chain is synthesized by living polymerization, and then a polymer compound is obtained by introducing polyethylene glycol, and then a polyacylated ethyleneimine Examples include a method of hydrolyzing a chain to obtain a linear polyethyleneimine.

  In addition, the method for synthesizing the compound (x2) used in the present invention has already been provided by the present inventors in JP 2007-197503 A, etc., so that it has a molecular weight within a specified range with reference to it. A compound may be synthesized.

  The method for synthesizing the compound (x3) used in the present invention has already been provided by the present inventors in the aforementioned Patent Documents 1 and 2, etc., so that a compound having a molecular weight within a specified range is referred to. Just synthesize.

  The molar ratio (a) :( b) of the polymer constituting the chain of each component of polyethyleneimine (a) and polyethylene glycol (b) in compound (x1) used in the present invention is not particularly limited. From the point of being excellent in dispersion stability and storage stability of the aqueous dispersion of the obtained silver-containing structure, it is usually in the range of (2) :( b) = 1: 1 to 100, particularly 1: 1 to 30. It is preferable to design as follows.

  When using the compound (x2), the molar ratio (a) :( c) of the polymer constituting the chain of each component of the polyethyleneimine (a) and the linear epoxy resin (c) is not particularly limited. However, from the viewpoint of excellent dispersion stability and storage stability of the aqueous dispersion of the obtained silver-containing structure, it is usually in the range of (a) :( c) = 1: 1 to 100, particularly 1: 1 to 1. It is preferable to design to be 30.

  When the compound (x3) is used, the molar ratio (a) :( b) :( c) of the polymer constituting the chain of each component of polyethyleneimine (a), polyethylene glycol (b), and linear epoxy resin (c) Is not particularly limited, but usually (a) :( b) :( c) = 1: 1 from the viewpoint of excellent dispersion stability and storage stability of the aqueous dispersion of the resulting silver-containing structure. It is preferable to design it to be in the range of ˜100: 1 to 100, particularly 1: 1 to 30: 1 to 30.

  The compound (X) used in the present invention is different from the polyethyleneimine (a) in which the silver nanoparticles (Y) can be stably present, in the compound (x1), in the polyethylene glycol (b) and in the compound (x2). The linear epoxy resin (c) and the compound (x3) have a structure derived from polyethylene glycol (b) and the linear epoxy resin (c). As described above, the polyethylene glycol (b) portion exhibits a high affinity with the solvent in the hydrophilic organic solvent, and the linear epoxy resin (c) portion exhibits a strong associative force in the hydrophilic organic solvent. Show. Further, when the linear epoxy resin (c) has an aromatic ring, the aqueous dispersion of the silver-containing structure is further stabilized by the interaction of the π electrons of the aromatic ring with silver. It is thought that it contributes to.

  In the production method of the present invention, the compound (X) is first dissolved or dispersed in an aqueous medium, that is, water or a mixed solvent of water and a hydrophilic organic solvent. In the case of compound (x1), polyethyleneimine (a) and polyethylene glycol (b), in the case of compound (x2), polyethyleneimine (a) and linear epoxy resin (c), in the case of compound (x3), polyethylene The combination of imine (a), polyethylene glycol (b), and linear epoxy resin (c) has different solubility and dispersibility in an aqueous medium, but it is necessary to uniformly dissolve or disperse it. The hydrophilic organic solvent that can be used here may be any one that can be mixed at least 5 parts by mass with respect to 100 parts by mass of water at 25 to 35 ° C. to obtain a uniform mixed solvent. , Ethanol, isopropyl alcohol, n-propyl alcohol, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, dimethylacetamide, dimethylformamide, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol Glycerin, dimethylsulfone oxide, dioxirane, N-methylpyrrolidone, dimethylimidazolidinone, sulfo Can be exemplified emissions etc., may be used individually or as a mixture of two or more. Various ionic liquids may be used.

  As the use ratio of the compound (X) and the aqueous medium, from the viewpoint of easy handling and easy reduction of silver ions, the silver content of the resulting silver-containing structure is improved. It is preferable to use it so that the density | concentration of compound (X) may be 1-20 mass%, and it is more preferable that it is 2-15 mass%. At this time, when the solubility and dispersibility of the compound (X) is insufficient, for example, mixing using ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, etc. The solubility / dispersibility can be adjusted by using a solvent. In order to dissolve or disperse the compound (X), usually, it may be allowed to stand at room temperature (25 ° C.) or stirred, and may be subjected to ultrasonic treatment, heat treatment or the like as necessary. Further, when the compatibility with the aqueous medium is low due to the crystallinity of the compound (X), for example, the compound (X) is dissolved or swollen with a small amount of a good solvent and then dispersed in the target aqueous medium. It is also possible to make it. At this time, it is more effective to perform ultrasonic treatment or heat treatment (about 80 ° C.).

  After preparing the solution or dispersion of the compound (X), the silver compound is mixed. At this time, from the viewpoint of increasing the silver content in the resulting silver-containing structure, 100 parts by mass of the compound (X) The silver is preferably used in an amount of 400 to 9900 parts by mass. Furthermore, it is preferable to mix so that it may become 2-80 mass% as a non volatile matter from a viewpoint which improves productivity by reducing the usage-amount of an aqueous medium, and can control a reductive reaction easily. More preferably, it is used so that it may become 900-9900 mass parts as silver and 3-50 mass% as a non volatile matter with respect to 100 mass parts of compound (X).

  At this time, as a silver compound that can be used, any silver compound (Y) can be obtained by a reduction reaction. Examples thereof include silver nitrate, silver oxide, silver acetate, silver fluoride, silver acetylacetonate, and benzoic acid. Silver oxide, silver carbonate, silver citrate, silver hexafluorophosphate, silver lactate, silver nitrite, silver pentafluoropropionate, etc., from the viewpoint of ease of handling and industrial availability, silver nitrate or silver oxide It is preferable to use it.

  In the above step, the method of mixing the silver compound with the aqueous medium in which the compound (X) is dissolved or dispersed is not particularly limited, and the medium in which the compound (X) is dissolved or dispersed is not limited. A method of adding a silver compound, a reverse method thereof, or a method of mixing while simultaneously charging in another container may be used. A mixing method such as stirring is not particularly limited.

  At this time, in order to accelerate the reduction reaction, it may be heated to about 30 to 70 ° C. as necessary, or a reducing agent may be used in combination.

  The reducing agent is not particularly limited. For example, hydrogen, hydrogenation can be performed because the reduction reaction can be easily controlled and can be easily removed from the reaction system in a subsequent purification step. Boron compounds such as sodium boron and ammonium borohydride, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, ethylene glycol and propylene glycol, aldehydes such as formaldehyde, acetaldehyde and propionaldehyde, ascorbic acid, citric acid and citric acid It is preferable to use acids such as sodium and hydrazines such as hydrazine and hydrazine carbonate. Among these, sodium borohydride, ascorbic acid, sodium citrate and the like are more preferable from the viewpoint of industrial availability and handling.

  The addition amount of the reducing agent is not particularly limited as long as it is an amount necessary for reducing silver ions, and the upper limit is not particularly specified, but it is 10 mol times or less of silver ions. Is preferable, and it is more preferable that it is 2 mol times or less.

  Moreover, the addition method of a reducing agent is not limited, For example, a reducing agent can be mixed as it is, or it dissolves and disperses | distributes in aqueous solution or another solvent. Further, the order of adding the reducing agent is not limited, either by adding the reducing agent to the solution or dispersion of compound (X) in advance or adding the reducing agent at the same time when the silver compound is mixed. Furthermore, after mixing several hours after mixing the solution of a compound (X) or a dispersion liquid, and a silver compound, the method of mixing a reducing agent may be sufficient.

  In particular, when using a raw material that does not dissolve or hardly dissolves in an aqueous medium such as silver oxide or silver chloride, a complexing agent may be used in combination. Examples of the complexing agent include propylamine, butylamine, diethylamine, dipropylamine, triethylamine, ammonia, ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, 1,3-diaminopropane, N, N , N ′, N′-tetramethyl-1,3-diaminopropane, triethylenetetramine, methylaminoethanol, dimethylaminoethanol, ethanolamine, diethanolamine, methyldiethanolamine, propanolamine, butanolamine, dimethylaminopropanol and the like. .

  The amount of the complexing agent added is not particularly limited as long as it is sufficient to be coordinated with silver oxide or the like to form a complex, and the upper limit is not particularly specified. It is preferable that it is 20 mole times or less. The method for adding the complexing agent is not limited. For example, the complexing agent can be mixed as it is or dissolved or dispersed in an aqueous solution or other solvent.

  The time required for the reduction reaction varies depending on the presence or absence of a reducing agent and the type of compound (X) used, but is usually 0.5 to 48 hours, and is adjusted to 0.5 to 24 hours from the viewpoint of industrial production. Is preferred. Examples of the preparation method include a method depending on the heating temperature, the amount of reducing agent and complexing agent added, and the timing thereof.

  After carrying out the reduction reaction, the purification step is started. At this time, it is preferable to perform concentration after adding an organic solvent. The concentration method is not particularly limited, and any of dialysis, centrifugation, precipitation, etc. may be used, or they may be used simultaneously. The organic solvent that can be used at this time is not particularly limited, but the viewpoint that the time required for the concentration step can be shortened, the organic solvent can be reused, and the mixture obtained in the previous step is mixed. From the viewpoint of being easy to handle, it is preferable that the organic solvent has a boiling point of 120 ° C. or lower, preferably 100 ° C. or lower. The amount used is not particularly limited, but it is preferable to mix the mixture obtained in the previous step so that the amount is 1.5 to 5 times, preferably 2 to 3 times. Further, as a concentration method, it is preferable to use a centrifugal separation method from the viewpoint of excellent industrial productivity. In this centrifugal concentration step, in addition to a part of the medium used in the previous step, the purpose is to remove a reducing agent and a complexing agent added as necessary, a counter ion of silver ions, and the like. . Therefore, it is preferable to use a concentration method according to the raw material used in the previous step, and the nonvolatile content is concentrated to 30% by mass or more, preferably 50% by mass or more.

  In general, metal nanoparticles in the size region of several tens of nm have characteristic optical absorption due to surface plasmon excitation, depending on the metal species. Therefore, by measuring the plasmon absorption of the obtained dispersion, it can be confirmed that silver is present as fine particles of nanometer order in the dispersion, and further, the dispersion is cast. It is also possible to observe the average particle diameter, distribution width, etc. in a TEM (transmission electron microscope) photograph of the film obtained in this manner.

  The concentrate obtained above can be directly used in the next step as an “aqueous dispersion of a silver-containing structure”. Further, a method in which a desired aqueous medium is appropriately added to the one-concentrated one, and the mixture is stirred and mixed to form an aqueous dispersion of a silver-containing structure, and the concentrate is powdered by vacuum drying, freeze drying, etc. Any of the methods of newly dispersing in the desired aqueous medium to form an “aqueous dispersion” may be used.

  The silver paste of the present invention is obtained by adding the compound (Z) having a functional group capable of reacting with the nitrogen atom in the polyethyleneimine (a) to the aqueous dispersion of the silver-containing structure obtained above. Can do. The addition method is not particularly limited, and for example, the compound (Z) can be mixed as it is or dissolved or dispersed in an aqueous solution or other solvent.

  The compound (Z) used in the present invention can be used without particular limitation as long as it is generally commercially available or can be synthesized, and specifically, a nitrogen atom in polyethyleneimine (Z). An aldehyde compound, an epoxy compound, an acid anhydride, a carboxylic acid, an inorganic acid, etc., which react with aldehyde to form an alcohol, form an amide bond, or form a quaternary ammonium ion. For example, formaldehyde, acetaldehyde, propionaldehyde, acrolein, benzaldehyde, cinnamaldehyde, perylaldehyde, ethylene oxide, propylene oxide, butylene oxide, 2,3-butylene oxide, isobutylene oxide, 1-methoxy-2-methylpropylene oxide, butyric acid-glycidyl Glycidyl methyl ether, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxydodecane, 1,4-butanediol diglycidyl ether, 1,2-epoxy-5-hexene, 1,2-epoxy-9-decene, 2-phenylpropylene oxide, stilbene oxide, glycidyl methyl ether, ethyl glycidyl ether, Tyl glycidyl ether, glycidyl isopropyl ether, tert-butyl glycidyl ether, allyl glycidyl ether, glycidyl phenyl ether, benzyl glycidyl ether, glycidyl stearate, epoxy succinic acid, 1,5-hexadiene diepoxide, 1,7-octadiene diepoxide 2,2-bis (4-glycidyloxyphenyl) propane, ethylene glycol diglycidyl ether, neopentyl glycol glycidyl ether, acetic anhydride, maleic anhydride, citraconic anhydride, diacetyl-tartaric anhydride, phthalic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1-cyclohexene-1,2-dicarboxylic anhydride, o-acetyl-malic anhydride, (2-methyl-2-propenyl) succinic acid Anhydride, 1,2-naphthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, 2,3-anthracene dicarboxylic anhydride, 2,3-dimethylmaleic anhydride, 3-methylglutaric anhydride, 3-methylphthalic anhydride, 4-methoxybenzoic anhydride, 4-methylphthalic anhydride, benzoic anhydride, succinic anhydride, butyl succinic anhydride, decyl succinic anhydride, dodecyl succinic anhydride, Hexadecyl succinic anhydride, octadecyl succinic anhydride, octadecenyl succinic anhydride, isooctadecenyl succinic anhydride, tetradecenyl succinic anhydride, nonenyl succinic anhydride, trimellitic anhydride, butyric anhydride, Propionic acid anhydride, heptanoic acid anhydride, decanoic acid anhydride, n-octanoic acid anhydride, nonanoic acid anhydride, oleic acid Water, valeric anhydride, palmitic anhydride, phenoxyacetic anhydride, pivalic anhydride, stearic anhydride, crotonic anhydride, diglycolic anhydride, glutaric anhydride, exo-3,6- Epoxy-1,2,3,6-tetrahydrophthalic anhydride, itaconic anhydride, formic acid, acetic acid, propionic acid, ascorbic acid, citric acid, tartaric acid, maleic acid, fumaric acid, succinic acid, oxalic acid, benzoic acid , P-toluenesulfonic acid, glucuronic acid, hyaluronic acid, gluconic acid, hydrogen peroxide, phosphoric acid, nitric acid, nitrous acid, boric acid and the like may be used alone or in combination of two or more. Also good.

  Although it does not specifically limit as addition amount of the said compound (Z), From the point which is excellent in the storage stability of the silver paste obtained, 0.1-0.1 with respect to the ethyleneimine unit in a polyethyleneimine (a) normally. It is preferable to use it in a range of 5 times molar equivalent, particularly 0.25 to 1 times molar equivalent.

  Melting | fusing point of the silver containing structure which has the said compound (X) and silver nanoparticle (Y) as a main component is 130 to 160 degreeC. However, by adding the compound (Z) having a functional group capable of reacting with a nitrogen atom of polyethyleneimine (a) to an aqueous dispersion of a silver-containing structure, the melting point in a dry state is lowered by 20 to 30 ° C. The silver paste can be obtained. Melting | fusing point in the dry state of the said silver paste is the range of 100 to 150 degreeC, Preferably it is the range of 100 to 130 degreeC.

  Subsequently, the obtained silver paste is applied onto a solid substrate, but the application method is not particularly limited. For example, the application method is a method using a spin coater, bar coater, applicator, various printing machines, printers, dispensers, etc., a method by dipping into silver paste, a method using a flow gun or a flow coater, spraying, etc. Examples include spraying, brushing, puffing, roller coating, and the like. The shape formed by coating can be applied by selecting various thickness lines, fine patterns, patterns, etc. from various methods according to the purpose.

  The silver paste of the present invention is excellent in adhesion to a solid substrate by itself, but any component selected according to the purpose may be mixed. The components that can be mixed are not particularly limited, and for electronic materials, various conductive material components, components that improve the affinity and adhesion to electronic materials, and the like, for paints. For example, a component that improves the affinity and adhesion to the substrate, a component that smoothes the surface or controls unevenness, a solvent having various boiling points, etc. It is a component that improves adhesion and adhesion, a viscosity modifier, etc. If it is for color materials, it is various colored components such as various polymers, ceramics, etc., for three-dimensional molded products such as containers and structures If there are, various raw materials, materials, solvents, or various additives such as coupling agents, crosslinking agents, leveling agents, etc. suitable for various purposes such as various polymers, coupling agents, crosslinking agents, etc. can be mentioned. .

  The conductive molded product of the present invention can be obtained by drying the solid base material after the silver paste application obtained above, but the method is not particularly limited. For example, the silver paste is coated on a base material by coating or the like, coated, laminated, a molded product filled with the silver paste using a mold or a mold, and the like, Simultaneously while heating the silver paste using a drying method using various heating devices such as a dryer, oven, thermostat, hot stage, etc., or using an injection molding machine, an extrusion molding machine, a compression molding machine, a blow molding machine, etc. The method of shape | molding, the method of naturally drying at room temperature of 25 to 30 degreeC, etc. are mentioned. The drying conditions are not particularly limited, and are desirably selected as appropriate according to the purpose of use, the solid substrate to be used, additives, and the like. As the solid base material used in the present invention, the glass transition temperature is relatively low, for example, it can be used even when it is 180 ° C. or less, and the solvent remaining in the silver paste when the temperature at the time of drying is too low. The drying temperature is essential to be in the range of 25 to 150 ° C., and preferably in the range of 80 to 150 ° C., because removal may be insufficient and characteristics such as conductivity may not be sufficiently exhibited. In addition, although the film of the electroconductive molded product of the present invention is obtained by drying the silver paste, a part of the compound (X) and the compound (Z) reacts to form a new one. When it is a compound (particularly when a compound having a relatively large molecular weight and low volatility such as an epoxy compound is used as the compound (Z)), or the compound (Z) is partially decomposed by the firing temperature. It may be contained in a state (particularly when a low molecular weight organic acid or inorganic acid is used), and in the present application, these modified products are also included.

  The solid substrate used in the conductive molded product of the present invention is not particularly limited as long as it can apply the silver paste and adsorb it. As for the shape, in addition to a film shape, a sheet shape, a plate shape, a three-dimensional molded product or the like having a simple shape or a complicated shape engraved or the like can be used. Substrates having various surface shapes such as a smooth surface, an embossed surface, and a complex uneven surface can be used as the shape of the substrate surface. As the material, a base material made of an organic material such as a polymer, a base material made of an inorganic material such as glass, metal, or ceramic, or a base material made of a hybrid material obtained by mixing these materials can be used. Representative examples of the substrate include polyethylene, polypropylene, polycarbonate, polyester, polystyrene, unsaturated polyester resin, vinyl chloride resin, epoxy resin, phenol resin, melamine resin, urea resin, AS resin, ABS resin, poly (meth). Use various polymers such as acrylate, poly (meth) acrylamide, polyvinyl alcohol, vinylidene chloride resin, acetal resin, polyamide, polyurethane, polyethylene terephthalate, polybutylene terephthalate, polyimide, liquid crystal polymer, polyphenylene sulfide, polysulfone, or wood Organic base materials, or base materials obtained by mixing these organic materials, aluminum, iron, stainless steel, copper, lead, titanium, castings, obtained by combining various metals Species alloy, silicon, ceramic, inorganic substrate comprises a semiconductor such as glass or the like. Since the silver paste of this invention has the characteristics that electroconductivity develops at the low temperature of 150 degrees C or less, even if it is a solid base material whose glass transition temperature is 180 degrees C or less, it can be used conveniently.

  The conductive molded product of the present invention is obtained by applying the silver paste on the substrate, and the silver paste layer or silver nanoparticles are heat-treated and dried on the substrate. An organic-inorganic composite layer that has been fused or crystallized is laminated. The silver paste layer and the organic / inorganic composite layer are metal laminates obtained by repeatedly applying the same or different silver paste layer and the organic / inorganic composite layer multiple times on a substrate. There may be. At that time, the shape, area, thickness, conditions, method, and the like to be applied may be the same or different. Further, the same or different silver paste layer to be repeatedly applied, and a layer coated with a material not containing silver nanoparticles and components fused or crystallized by the above treatment between the organic-inorganic composite layers. Is also possible.

  In the above-mentioned pre-process, various steps, post-processes, etc., various processes such as dehydration, solvent removal, natural drying, freeze-drying, heating, ultraviolet irradiation, and electron beam irradiation are suitably performed according to various purposes. These processing methods can be used without any particular limitation.

  The form of the molded product of the present invention obtained by the above production method is not particularly limited. In particular, examples of the shape of the molded product obtained by the representative example described above include a coating film, a coating film, a coating, a bonded product, a laminated plate, a sealed product, a film, a sheet, a board, and a fibrous molded product. , Tube-shaped molded products, three-dimensional molded products, gel-shaped molded products, solid sol-shaped molded products, and the like.

The conductivity of the conductive molded product of the present invention is an intrinsic volume resistivity of 1 × 10 ⁻³ Ω · cm or less, preferably 1 × 10 ⁻⁴ Ω · cm or less, more preferably 1 × 10 ⁻⁵ Ω. -It is cm or less. Conventionally, in order to obtain such conductivity, it has been considered that the protective agent (corresponding to the compound (X) in the present invention) in the metal nanoparticle dispersion must be removed. Therefore, in Japanese Patent Application Laid-Open No. 2004-218055 and Japanese Patent Application Laid-Open No. 2004-273205, a low molecular weight protective agent is used in order to facilitate the removal of the protective agent, or a complicated dispersion solvent (organic solvent) is used. A method of preparing a paste containing metal nanoparticles by applying preparation, applying the paste, and removing the protective agent and solvent by heating or the like is employed. However, in the present invention, by adding the compound (Z) having a functional group capable of reacting with the nitrogen atom in the polyethyleneimine (a) to the aqueous dispersion of the above-described silver-containing structure, By changing the surface charge, promoting dispersion stabilization in the solvent, and removing the solvent removes the polyethyleneimine chain bonded to the compound having a functional group capable of reacting with the nitrogen atom in the polyethyleneimine from the surface of the silver nanoparticle. Since the melting point of the paste is lowered, the molded product can be made conductive without using complicated steps such as solvent conversion as described in JP-A-2004-218055 and JP-A-2004-273205. Furthermore, since the compound (X) remains in the film of the molded product, adhesion to various substrates is good. Also such inhibit the generation of cracks or fractures in the coating of the workpiece, in which also expressed the added value.

  The molded processed product of the present invention is obtained by adding polyethylene dispersion to an aqueous dispersion of a silver-containing structure containing silver nanoparticles (Y) in a dispersion formed by a compound (X) having a polyethyleneimine (a) skeleton in a solvent. The organic-inorganic composite obtained using the compound (Z) which has a functional group which can react with the nitrogen atom in imine (a) is contained. Conventionally, when a molded product using silver paste is obtained, it is not necessary to perform a very complicated process such as an exchange operation of various raw material components, which is performed to facilitate removal of organic components. It is a feature. Furthermore, the conductive molded product containing the organic-inorganic composite obtained by using the silver paste of the present invention has various chemical, electrical, magnetic, optical, colorant characteristics, etc. possessed by the silver nanoparticles. In addition, the organic component has properties such as moldability, film-forming property, adhesiveness and flexibility. The application is not limited, and can be used in a very wide range of fields such as catalysts, electronic materials, magnetic materials, optical materials, various sensors, color materials, medical examination applications, and the like. Since the proportion of silver that can be contained can be easily adjusted, the effects according to the purpose can be expressed efficiently, and there is almost no need for complicated processes or precise condition settings. As such, it is highly advantageous.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” represents “mass%”.

In the following examples, the equipment used is as follows.
¹ H-NMR: manufactured by JEOL Ltd., AL300, 300 Hz
Particle size measurement: FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.
TEM observation: JEM-2200FS, manufactured by JEOL Ltd.
TGA measurement: SII Nano Technology Co., Ltd., TG / DTA6300
Plasmon absorption spectrum: manufactured by Hitachi, Ltd., UV-3500
Volume resistivity: Mitsubishi Chemical Corporation, low resistivity meter Loresta EP
DSC measurement: SII Nano Technology Co., Ltd., DSC7200

<Synthesis of aqueous dispersion of compound (X) and silver-containing structure>
Synthesis Example 1 Synthesis of Compound (x1) and Synthesis of Aqueous Dispersion of Silver-Containing Structure Using the Compound 1-1 [Tosylation Reaction of Polyethylene Glycol]
Under a nitrogen atmosphere, 9.6 g of p-toluenesulfonic acid chloride was added to a mixed solution of 20.0 g (10.0 mmol) of methoxypolyethylene glycol [Mn = 2,000], 8.0 g (100.0 mmol) of pyridine and 20 ml of chloroform ( A chloroform (30 ml) solution containing 50.0 mmol) was added dropwise for 30 minutes with ice-cooling and stirring. After completion of dropping, the mixture was further stirred at a bath temperature of 40 ° C. for 4 hours. After completion of the reaction, 50 ml of chloroform was added to dilute the reaction solution. Subsequently, after sequentially washing with 100 ml of 5% hydrochloric acid aqueous solution, 100 ml of saturated aqueous sodium hydrogen carbonate solution and 100 ml of saturated saline solution, it was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The obtained solid was washed several times with hexane, filtered, and dried under reduced pressure at 80 ° C. to obtain 22.0 g of a tosylated product.

The measurement result of ¹ H-NMR of the obtained product is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 7.82 (d), 7.28 (d), 3.74-3.54 (bs), 3.41 (s), 2.40 (s)

1-2 [Synthesis of Compound (x1)]
2.0.0 g (0.8 mmol) of 5.39 g (2.5 mmol) of a methoxypolyethylene glycol compound having a p-toluenesulfonyloxy group at the terminal synthesized above and branched polyethyleneimine (manufactured by Aldrich, molecular weight 25,000) Then, 0.07 g of potassium carbonate and 100 ml of N, N-dimethylacetamide were stirred at 100 ° C. for 6 hours under a nitrogen atmosphere. To the resulting reaction mixture, 300 ml of a mixed solution of ethyl acetate and hexane (V / V = 1/2) was added, and after vigorous stirring at room temperature, the solid product was filtered. The solid was repeatedly washed twice with 100 ml of a mixed solution of ethyl acetate and hexane (V / V = 1/2), then dried under reduced pressure, and a compound (x1) in which polyethylene glycol was bound to branched polyethyleneimine 24.4 g of a solid was obtained.

The measurement result of ¹ H-NMR of the obtained product is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 3.50 (s), 3.05 to 2.20 (m)

1-3 [Synthesis of aqueous dispersion of silver-containing structure]
10.0 g of silver oxide was added to 138.8 g of an aqueous solution using 0.592 g of the compound (x1) obtained in 1-2, and the mixture was stirred at 25 ° C. for 30 minutes. Subsequently, when 46.0 g of dimethylethanolamine was gradually added with stirring, the reaction solution turned black-red and slightly exothermic, but was left as it was and stirred at 25 ° C. for 30 minutes. Thereafter, 15.2 g of a 10% ascorbic acid aqueous solution was gradually added with stirring. While maintaining the temperature, stirring was continued for another 20 hours to obtain a black-red dispersion.

  A mixed solvent of 200 ml of isopropyl alcohol and 200 ml of hexane was added to the dispersion obtained after completion of the reaction and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a mixed solvent of 50 ml of isopropyl alcohol and 50 ml of hexane was added to the precipitate and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, 20 g of water was further added to the precipitate and stirred for 2 minutes, and the organic solvent was removed under reduced pressure to obtain an aqueous dispersion of a silver-containing structure.

  The obtained dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by measuring a visible absorption spectrum of a 10-fold diluted solution, thereby confirming the formation of silver nanoparticles. Moreover, spherical silver nanoparticles (average particle diameter: 17.5 nm) were confirmed by TEM observation. As a result of measuring the silver content in the solid using TG-DTA, it was 97.2%.

Synthesis Example 2 Synthesis of Compound (x2) and Synthesis of Aqueous Dispersion of Silver-Containing Structure Using the Compound 2-1 [Synthesis of Monofunctional Epoxy Resin]
Bisphenol A type linear epoxy resin EPICLON AM-040-P (manufactured by DIC Corporation, epoxy equivalent 933) 18.7 g (20 m equivalent), 4-phenylphenol 1.28 g (7.5 mmol), 65% ethyltriphenyl acetate A phosphonium ethanol solution (0.26 ml, 0.12 mol%) and N, N-dimethylacetamide (50 ml) were mixed and reacted at 120 ° C. for 6 hours in a nitrogen atmosphere. After standing to cool, it was dropped into 150 ml of water, and the resulting precipitate was washed twice with methanol and then dried under reduced pressure at 60 ° C. to obtain a monofunctional epoxy resin. The yield of the obtained product was 19.6 g, and the yield was 98%.

¹ H-NMR measurement was performed, and as a result of considering the integration ratio of the epoxy group, 0.95 epoxy rings remained in one molecule of the bisphenol A type linear epoxy resin, and it was confirmed that the epoxy resin was a monofunctional epoxy resin.

The measurement result of ¹ H-NMR of the obtained monofunctional epoxy resin is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 7.55 to 6.75 (m), 4.40 to 3.90 (m), 3.33 (m), 2.89 (m), 2.73 (m), 1. 62 (s)

2-2 [Synthesis Example of Compound (x2)]
In a nitrogen atmosphere, 3.0 g (1.5 mmol) of a monofunctional epoxy resin obtained by the above synthesis, 7.5 g (0.3 mmol) of branched polyethylenimine (manufactured by Aldrich, molecular weight 25,000) and 60 ml of chloroform were added. The reaction was carried out at 50 ° C. with stirring for 2 hours. After completion of the reaction, drying under reduced pressure at 40 ° C. gave 10.5 g of a bisphenol A type epoxy-modified polyethyleneimine compound (x2).

  To 30 mg of the compound (x2) obtained above, 10 ml of pure water was added and stirred to dissolve. When the scattering intensity distribution was measured in order to observe the distribution state of the compound (x2) in the solution, a measurement result with an average particle size of 110 nm was obtained, which showed that micelles were well formed in water. .

[Synthesis of aqueous dispersion of silver-containing structure]
To 77.0 g of an aqueous solution using 0.250 g of the compound (x2) obtained in 2-2, 5.0 g of silver oxide was added and stirred at 25 ° C. for 30 minutes. Subsequently, when 23.0 g of dimethylethanolamine was gradually added with stirring, the reaction solution turned black-red and slightly exothermic, but was left as it was and stirred at 25 ° C. for 30 minutes. Thereafter, 7.6 g of a 10% ascorbic acid aqueous solution was gradually added with stirring. Stirring was continued for another 16 hours while maintaining the temperature to obtain a black-red dispersion.

  A mixed solvent of 100 ml of isopropyl alcohol and 100 ml of hexane was added to the dispersion liquid after completion of the reaction obtained above and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a mixed solvent of 25 ml of isopropyl alcohol and 25 ml of hexane was added to the precipitate and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, 10 g of water was added to the precipitate and stirred for 2 minutes, and the organic solvent was removed under reduced pressure to obtain an aqueous dispersion of a silver-containing structure.

  The obtained dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by measuring a visible absorption spectrum of a 10-fold diluted solution, thereby confirming the formation of silver nanoparticles. Further, spherical silver nanoparticles (average particle diameter 23.6 nm) were confirmed by TEM observation. And as a result of measuring silver content in solid using TG-DTA, 96.8% was shown.

Synthesis Example 3 Synthesis of Compound (x3) and Synthesis of Aqueous Dispersion of Silver-Containing Structure Using the Compound 3-1 [Synthesis Example of Compound (x3)]
The monofunctional epoxy resin obtained in Synthesis Example 2-1 (3.0 g, 1.5 mmol) and the acetone (50 ml) solution in Compound (x1) obtained in Synthesis Example 1-2, 14.4 g (0.48 mmol) Then, a solution of 60 ml of methanol was added and stirred at 60 ° C. for 2 hours under a nitrogen atmosphere. After completion of the reaction, the solvent was removed to obtain a compound (x3) obtained by bonding polyethylene glycol and an epoxy resin to branched polyethyleneimine.

3-2 [Synthesis of aqueous dispersion of silver-containing structure]
When 23.0 g of dimethylethanolamine was gradually added to 77.0 g of an aqueous solution using 0.263 g of the compound (x3) obtained in 3-1 above, a little heat was generated. Subsequently, when the reaction temperature was changed to 45 ° C. and gradually added to 5.0 g of silver nitrate, the reaction solution turned black-red. Thereafter, the reaction temperature was set to 50 ° C. and stirred for 4.5 hours to complete the reaction, and a black-red dispersion was obtained.

  A mixed solvent of 100 ml of isopropyl alcohol and 100 ml of hexane was added to the dispersion liquid after completion of the reaction obtained above and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a mixed solvent of 25 ml of isopropyl alcohol and 25 ml of hexane was added to the precipitate and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, 10 g of water was added to the precipitate and stirred for 2 minutes, and the organic solvent was removed under reduced pressure to obtain an aqueous dispersion of a silver-containing structure.

  The obtained dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at around 400 nm by measuring a visible absorption spectrum of a 10-fold diluted solution, thereby confirming the formation of silver nanoparticles. Moreover, spherical silver nanoparticles (average particle diameter 18.8 nm) were confirmed by TEM measurement. Moreover, as a result of measuring the silver content in solid using TG-DTA, 96.6% was shown.

Example 1
Water was added to the aqueous dispersion of the silver-containing structure obtained in Synthesis Example 1 to obtain a dispersion having a solid content of 30%. Propionaldehyde corresponding to 0.1 equivalent of ethyleneimine unit in polyethyleneimine was added to this dispersion and stirred to obtain a silver paste. This silver paste was applied onto a slide glass with a bar coater (RDS08) to produce a silver coating. After drying at room temperature of 20 ° C. to 30 ° C. for 1 hour, a part of the film was peeled off and subjected to DSC measurement. As a result, the melting point was 123 ° C. After heating the silver coating film together with the slide glass at 150 ° C. for 30 minutes, the volume resistivity of the coating film measured by the four-terminal method was measured and found to be 5.6 μΩ · cm.

Example 2
In Example 1, the volume resistivity after processing in the same manner as in Example 1 except that the heating temperature was 120 ° C. was 9.8 μΩ · cm.

Example 3
Ethanol was added to the aqueous dispersion of the silver-containing structure obtained in Synthesis Example 1 to obtain a dispersion having a solid content of 30%. To this dispersion, nitric acid corresponding to 0.5 equivalent of ethyleneimine unit in polyethyleneimine and acetic anhydride corresponding to 0.3 equivalent of ethyleneimine unit were added and stirred to obtain a silver paste. This silver paste was applied onto a slide glass in the same manner as in Example 1 to produce a silver coating. The melting point by DSC measurement was 123 ° C. When the silver film was heated with the slide glass at 150 ° C. for 30 minutes, the volume resistivity was 4.7 μΩ · cm.

Example 4
In Example 3, the volume resistivity after processing in the same manner as in Example 3 except that the heating temperature was 120 ° C. was 24 μΩ · cm.

Example 5
Water and ethanol were added to the aqueous dispersion of the silver-containing structure obtained in Synthesis Example 1 at 80:20 to obtain a dispersion having a solid content of 30%. To this dispersion, nitric acid corresponding to 0.5 equivalent of ethyleneimine unit in polyethyleneimine and acetic acid corresponding to 0.5 equivalent of ethyleneimine unit were added and stirred to obtain a silver paste. This silver paste was applied onto a slide glass in the same manner as in Example 1 to produce a silver coating. The melting point by DSC measurement was 122 ° C. When the silver coating was heated at 150 ° C. for 30 minutes, the volume resistivity was 3.0 μΩ · cm.

Example 6
In Example 5, the volume resistivity after processing in the same manner as in Example 5 except that the heating temperature was 120 ° C. was 4.6 μΩ · cm.

Example 7
In Example 5, the volume resistivity after processing in the same manner as in Example 5 except that the heating temperature was 100 ° C. was 7.7 μΩ · cm.

Example 8
In Example 5, the volume resistivity after processing in the same manner as in Example 5 except that the heating temperature was 80 ° C. and the processing time was 8 days was 13 μΩ · cm.

Example 9
In Example 5, the volume resistivity after processing in the same manner as in Example 5 except that the heating temperature was 60 ° C. and the processing time was 8 days was 18 μΩ · cm.

Example 10
In Example 5, the volume resistivity after treatment in the same manner as in Example 5 was 18 μΩ · cm, except that the sample was allowed to stand at room temperature of 25 ° C. for 14 days.

Example 11
When the silver paste obtained in Example 5 was applied to a polyethylene terephthalate film (glass transition temperature: about 70 ° C.) with a bar coater (RDS08) and heated at 120 ° C. for 30 minutes, the volume resistivity was 5.2 μΩ · cm. (The film as the base material was slightly deformed, but no peeling of the silver film was observed).

Example 12
In Example 11, the volume resistivity after processing in the same manner as in Example 11 except that the heating temperature was 100 ° C. was 8.2 μΩ · cm (the film as the substrate was slightly deformed). However, no peeling of the silver film was observed.)

Example 13
When the nano silver paste obtained in Example 5 was applied to a polyethylene naphthalate film (glass transition temperature: about 110 ° C.) with a bar coater (RDS08) and heated at 120 ° C. for 30 minutes, the volume resistivity was 5.1 μΩ · (The film as the base material was slightly deformed, but no peeling of the silver film was observed).

Example 14
In Example 13, the volume resistivity after processing in the same manner as in Example 13 except that the heating temperature was 100 ° C. was 8.0 μΩ · cm.

Example 15
When the silver paste obtained in Example 5 was applied to glossy paper (MC glossy paper) with a bar coater (RDS08) and heated at 120 ° C. for 30 minutes, the surface resistivity was 1.7 × 10 ⁻¹ Ω / □. It was. In all the applied portions, no cracks or the like were observed in the coating, and no peeling occurred.

Example 16
In Example 15, the surface resistivity after processing as in Example 15 except that the heating temperature was 100 ° C. was 8.3 × 10 ⁻¹ Ω / □. In all the applied portions, no cracks or the like were observed in the coating, and no peeling occurred.

Example 17
A 1 cm × 1 cm square-polymethyl methacrylate resin (glass transition temperature: about 110 ° C.) was immersed in the nanosilver paste obtained in Example 5 for 1 minute and heated at 120 ° C. for 30 minutes. Was 6.0 × 10 ⁻² Ω / □. A silver film was formed on the front surface of the square pillar resin used as the base material, and no peeling or cracking was observed.

Example 18
In Example 15, the surface resistivity after processing in the same manner as in Example 15 except that the heating temperature was 100 ° C. was 1.1 × 10 ⁰ Ω / □.

Example 19
The silver paste obtained in Example 5 was injected into a polycarbonate tube (glass transition temperature: about 150 ° C.) having an inner diameter of 1 cm using a syringe, and the internal solution was removed with a syringe after 1 minute. The tube with the silver paste applied to the inner wall was heated at 120 ° C. for 30 minutes, the tube was cut, and the surface resistivity was measured. The result was 6.3 × 10 ⁻² Ω / □. A silver film was formed on the entire surface inside the tube, and no peeling or cracking was observed.

Example 20
In Example 19, the surface resistivity after processing in the same manner as in Example 19 except that the heating temperature was 100 ° C. was 1.0 × 10 ⁰ Ω / □. A silver film was formed on the entire surface inside the tube, and no peeling or cracking was observed.

Example 21
Water was added to the aqueous dispersion of the silver-containing structure obtained in Synthesis Example 2 to obtain a dispersion having a solid content of 30%. To this dispersion, nitric acid corresponding to 0.5 equivalent of ethyleneimine unit in polyethyleneimine and acetic acid corresponding to 0.25 equivalent of ethyleneimine unit were added and stirred to obtain a silver paste. This silver paste was applied onto a slide glass in the same manner as in Example 1 to produce a silver coating. The melting point by DSC measurement was 132 ° C. The volume resistivity after heating the silver coating with the slide glass at 150 ° C. for 30 minutes was 6.7 μΩ · cm.

Example 22
In Example 21, the volume resistivity after processing in the same manner as in Example 21 except that the heating temperature was 120 ° C. was 9.8 μΩ · cm.

Example 23
Water and ethanol were added to the aqueous dispersion of the silver-containing structure obtained in Synthesis Example 3 at 80:20 to obtain a dispersion having a solid content of 30%. Nitric acid corresponding to 0.25 equivalent of ethyleneimine unit in polyethyleneimine was added to this dispersion and stirred to obtain a silver paste. This silver paste was applied onto a slide glass in the same manner as in Example 1 to produce a silver coating. The melting point by DSC measurement was 135 ° C. The volume resistivity after heating the silver coating with the slide glass at 150 ° C. for 30 minutes was 6.6 μΩ · cm.

Example 24
In Example 23, the volume resistivity after processing in the same manner as in Example 23 except that the heating temperature was 120 ° C. was 16 μΩ · cm.

Comparative Example 1
Water and ethanol were added to the aqueous dispersion of the silver-containing structure obtained in Synthesis Example 1 at 80:20 to obtain a dispersion having a solid content of 30% without any other additives. This dispersion was applied onto a slide glass in the same manner as in Example 1 to produce a silver film. The melting point by DSC measurement was 157 ° C. The volume resistivity of the film after heating at 150 ° C. for 30 minutes was 30 μΩ · cm.

Comparative Example 2
The volume resistivity of the silver coating obtained in Comparative Example 1 after heating at 120 ° C. for 30 minutes was 340 μΩ · cm.

Comparative Example 3
The volume resistivity of the silver coating obtained in Comparative Example 1 after heating at 100 ° C. for 30 minutes was not measurable.

  In addition, the silver paste obtained in Examples 1, 3, 5, 21, and 23 and the dispersion of Comparative Example 1 did not aggregate and settle even after one month of standing at room temperature of 20 ° C. to 30 ° C. , TEM observation confirmed that there was no change in the size of the nano silver particles.

It is a DSC measurement result of the silver film obtained using the silver paste obtained in Example 5, and the dispersion liquid obtained in Comparative Example 1.

Claims (10)

(1) Compound (x1) formed by bonding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000,
Compound (x2) in which linear epoxy resin (c) is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and polyethyleneimine having a number average molecular weight of 500 to 50,000 Compound (x3) formed by binding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and linear epoxy resin (c) to the amino group in (a)
One or more compounds (X) selected from the group consisting of: silver nanoparticles (Y);
An aqueous dispersion of a silver-containing structure comprising as a main constituent;
A compound (Z) having a functional group capable of reacting with a nitrogen atom of polyethyleneimine (a) in the compound (X), and a silver paste having a melting point of 100 to 150 ° C. in a dry state as a solid substrate Applying on top,
(2) A step of drying the solid base material after applying the silver paste obtained in the step (1) at 25 ° C. to 150 ° C.,
A process for producing a conductive molded product, comprising: The compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a) is one or more compounds selected from the group consisting of aldehyde compounds, epoxy compounds, acid anhydrides, carboxylic acids and inorganic acids. The manufacturing method according to claim 1. The method according to claim 1, wherein the compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a) is an inorganic acid. The compound (X) and the compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a) are mixed with the compound (X) with respect to 1 mol of the ethyleneimine unit. The manufacturing method of any one of Claims 1-3 used so that the number of moles of the functional group which can react with the nitrogen atom in (Z) will be 0.25-1 mol. The glass transition temperature of the said solid base material is 180 degrees C or less, The manufacturing method in any one of Claims 1-4. On a solid substrate,
A compound (x1) obtained by bonding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000,
Compound (x2) in which linear epoxy resin (c) is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and polyethyleneimine having a number average molecular weight of 500 to 50,000 Compound (x3) formed by binding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and linear epoxy resin (c) to the amino group in (a)
One or more compounds (X) selected from the group consisting of: a silver nanoparticle (Y), and a compound having a functional group capable of reacting with a nitrogen atom of polyethyleneimine (a) in the compound (X) (Z And a film having a melting point of 100 to 150 ° C. The compound (Z) having a functional group capable of reacting with the nitrogen atom of the polyethyleneimine (a) is one or more compounds selected from the group consisting of aldehyde compounds, epoxy compounds, acid anhydrides, carboxylic acids and inorganic acids. The conductive molded product according to claim 6. The conductive molded article according to claim 6 or 7, wherein the solid substrate has a glass transition temperature of 180 ° C or lower. A compound (x1) obtained by bonding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000,
Compound (x2) in which linear epoxy resin (c) is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and polyethyleneimine having a number average molecular weight of 500 to 50,000 Compound (x3) formed by binding polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and linear epoxy resin (c) to the amino group in (a)
One or more compounds (X) selected from the group consisting of: silver nanoparticles (Y);
An aqueous dispersion of a silver-containing structure comprising as a main constituent;
A compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a);
A silver paste comprising: a silver paste having a melting point in the dry state of 100 to 150 ° C. The compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a) is one or more compounds selected from the group consisting of aldehyde compounds, epoxy compounds, acid anhydrides, carboxylic acids and inorganic acids. The silver paste according to claim 9.

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