JP6905328B2 - Composition for forming a metal plating layer - Google Patents

Description

The present invention is a metal comprising a novel composition for forming a metal plating layer, a method for forming a metal plating layer using the composition for forming a metal plating layer, and a sintered body of the composition for forming a metal plating layer. The present invention relates to a substrate having a plating layer.

Conventionally, electronic components such as circuits, wirings, and electrodes have been manufactured by an etching method. However, there is a problem that the process is complicated and the cost is high. Therefore, as an alternative method, a method of directly forming by printing is being studied.

Among metals, bulk silver has a high melting point of 962 ° C., but nano-sized silver particles (silver nanoparticles) fuse with each other at a temperature of about 100 ° C., so if this is used, heat resistance It is possible to form a conductive electronic component on a general-purpose plastic substrate having a low temperature. However, the problem is that nano-sized metal particles tend to aggregate.

Patent Document 1 describes that aggregation is suppressed by coating the surface of silver nanoparticles with amines, and the surface-modified silver nanoparticles are subjected to hydrocarbons such as n-octane, decalin, and tetradecane 10 to 10. The composition for forming a metal plating layer obtained by dispersing 50% by weight in a dispersion medium containing 50% by weight and 50 to 90% by weight of an alcohol such as n-butanol or cyclohexaneethanol has excellent dispersion stability of silver nanoparticles and can be printed. It is described that it can be suitably used for directly forming electronic parts by the method, and that a sintered body having conductivity can be obtained by sintering the composition for forming a metal plating layer.

International Publication No. 2014/021270

However, since the sintered body obtained by using the composition for forming a metal plating layer described in Patent Document 1 has low adhesion to the substrate, for example, in order to prevent damage to the sintered body during transportation, it is baked. When the protective film is attached to the surface of the body, there is a problem that the sintered body is also peeled off from the substrate when the protective film is peeled off.

When a ceramic substrate is used as the substrate, a certain degree of adhesion can be obtained between the substrate and the sintered body due to the anchor effect caused by the unevenness existing on the substrate surface, but a substrate having excellent surface smoothness such as a glass substrate can be obtained. In this case, the anchor effect could not be obtained, and even if the plated film was formed, it was a problem that it was peeled off from the substrate due to shrinkage accompanying the film growth. Further, it is conceivable to apply a surface treatment to the substrate to improve the adhesion to the sintered body, but there is a problem that the number of steps increases and the cost increases.

Therefore, the composition for forming a metal plating layer containing metal nanoparticles is required to have the following characteristics 1 to 4.
1. 1. 2. Have a viscosity suitable for coating. 2. It contains metal nanoparticles in a highly dispersed state and has a uniform composition. 3. By subjecting to sintering, a sintered body having conductivity can be obtained. By subjecting to sintering, a sintered body with excellent substrate adhesion can be obtained.

As a method for improving the adhesion of the sintered body to the substrate, for example, an adhesive-imparting material such as a rubber-like elastic body, a terpene resin, a rosin resin, or a petroleum resin, a silane coupling agent, or the like can be added. Conceivable. However, when these are added to the composition for forming a metal plating layer, the coatability may be lowered due to the thickening, or the conductivity of the obtained sintered body may be lowered.
In addition, a method of adding a compound having a hydroxyl group, a carbonyl group, an ether bond, or the like to improve the adhesion of the sintered body to the substrate by an interaction such as a hydrogen bond is also conceivable. When these are added to the metal nanoparticles, the metal nanoparticles tend to aggregate, and it becomes difficult to maintain the composition uniformly.
That is, at present, no method has been found for imparting the characteristics (4) (adhesion to the substrate) to the composition for forming the metal plating layer without impairing the above-mentioned characteristics (1) to (3).

Therefore, an object of the present invention is to provide a composition for forming a metal plating layer, which is excellent in coatability and dispersibility of metal nanoparticles, and which forms a sintered body having excellent substrate adhesion by sintering.
Another object of the present invention is to provide a method for forming a metal plating layer using the composition for forming a metal plating layer.
Another object of the present invention is to provide a substrate provided with a plating layer made of a sintered body of the composition for forming a metal plating layer.

As a result of diligent studies to solve the above problems, the present inventor has found that a composition obtained by dispersing metal nanoparticles whose surface is coated with an organic protective agent in a specific dispersion medium is highly dispersed without agglomeration of the metal nanoparticles. A specific amount of (meth) acrylate and a thermal radical polymerization initiator are added to the composition, and heat treatment is performed after coating to form a crosslinked structure in the (meth) acrylate. As a result, it has been found that a metal plating layer having excellent substrate adhesion can be obtained without deteriorating the coatability. The present invention has been completed based on these findings.

In addition, in this specification, "nanoparticle" means a particle which the size (average primary particle diameter) of a primary particle is less than 1000 nm. The particle size is determined by the dynamic light scattering method. The boiling point in the present specification is a value under normal pressure (760 mmHg).

That is, the present invention contains the following components (A), (B), (C), and (D), and the component (B) is 20 to 100 parts by weight, (C) with respect to 100 parts by weight of the component (A). ) Is contained in an amount of 4 to 10 parts by weight based on 100 parts by weight of the component (A) to provide a composition for forming a metal plating layer.
Component (A) Component: Surface-modified metal nanoparticles having a structure in which the surface of the metal nanoparticles is coated with an organic protective agent (B) Component: Dispersion containing alcohol (b-1) and hydrocarbon (b-2) Medium (C) component: (Meta) acrylate (D) component: Thermal radical polymerization initiator

The present invention also comprises a compound in which the organic protective agent constituting the component (A) has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group, and a thiol group. Provided is the above-mentioned composition for forming a metal plating layer.

In the present invention, the organic protective agent constituting the component (A) has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group, and a thiol group. The above-mentioned composition for forming a metal plating layer, which is a compound of the number 4 to 18, is provided.

The present invention also provides the above-mentioned composition for forming a metal plating layer, wherein the (meth) acryloyl equivalent of the (meth) acrylate is 250 to 5000 g / eq.

The present invention also provides the above-mentioned composition for forming a metal plating layer, wherein the (meth) acrylate is a urethane (meth) acrylate.

The present invention also provides the above-mentioned composition for forming a metal plating layer, wherein the thermal radical polymerization initiator is an organic peroxide.

The present invention also provides the above-mentioned composition for forming a metal plating layer, wherein the alcohol (b-1) is an alicyclic secondary alcohol and / or an alicyclic tertiary alcohol.

The present invention also provides the above-mentioned composition for forming a metal plating layer having a viscosity (at 25 ° C. and a shear rate of 10 (1 / s)) of 1 to 100 mPa · s.

The present invention also provides the above-mentioned composition for forming a metal plating layer, wherein the metal nanoparticles constituting the component (A) are silver nanoparticles.

The present invention also provides the above-mentioned composition for forming a metal plating layer, which is used for forming a metal plating layer by inkjet printing, gravure printing, or flexographic printing.

The present invention also provides the above-mentioned composition for forming a metal plating layer, which is used for forming a metal plating layer on a glass substrate.

The present invention also provides a method for forming a metal plating layer, which forms a metal plating layer on a substrate using the above-mentioned composition for forming a metal plating layer.

The present invention also provides a substrate provided with a metal-plated layer made of a sintered body of the above-mentioned composition for forming a metal-plated layer.

The composition for forming a metal plating layer of the present invention has a low viscosity and is excellent in coatability. Therefore, for example, when coating using an inkjet printing method, the composition for forming a metal plating layer adheres to the nozzle opening and causes flight bending (injection at an angle different from the set injection angle), or the nozzle. It is possible to print with high accuracy without clogging the mouth and making injection impossible. Further, the composition for forming a metal plating layer of the present invention is applied to the surface of a base material and then sintered (even at low temperature sintering) to cover the base material (particularly, a smooth substrate such as a glass substrate). To form a sintered body having excellent adhesion. Therefore, even if a protective film is attached to the surface of the sintered body for the purpose of preventing damage, for example, the sintered body will not be peeled off together when the protective film is peeled off. Therefore, the composition for forming a metal plating layer of the present invention can be suitably used for producing a metal plating layer on a smooth substrate.

[Composition for forming a metal plating layer]
The composition for forming a metal plating layer of the present invention contains the following components (A), (B), (C), and (D), and contains 20 to 20 to 100 parts by weight of the component (B) with respect to 100 parts by weight of the component (A). It is characterized by containing 100 parts by weight and 4 to 10 parts by weight of the component (C) with respect to 100 parts by weight of the component (A).
Component (A) Component: Surface-modified metal nanoparticles having a structure in which the surface of the metal nanoparticles is coated with an organic protective agent (B) Component: Dispersion containing alcohol (b-1) and hydrocarbon (b-2) Medium (C) component: (Meta) acrylate (D) component: Thermal radical polymerization initiator

(Surface-modified metal nanoparticles (A))
The surface-modified metal nanoparticles (A) in the present invention have a structure in which the surface of the metal nanoparticles is coated with an organic protective agent. Therefore, in the surface-modified metal nanoparticles (A) in the present invention, the spacing between the metal nanoparticles is secured and aggregation is suppressed. That is, the surface-modified metal nanoparticles (A) in the present invention are excellent in dispersibility.

The surface-modified metal nanoparticles (A) are a metal nanoparticle portion and a surface-modified portion that covers the metal nanoparticles (that is, a portion that is coated with the metal nanoparticles and is formed by an organic protective agent). The proportion of the surface-modified portion is, for example, about 1 to 20% by weight (preferably 1 to 10% by weight) based on the weight of the metal nanoparticle portion. The weight of each of the metal nanoparticles and the surface-modified portion of the surface-modified metal nanoparticles can be obtained from, for example, the thermogravimetric analysis of the surface-modified metal nanoparticles and the weight loss rate in a specific temperature range.

The average primary particle size of the metal nanoparticles portion of the surface-modified metal nanoparticles (A) is, for example, 0.5 to 100 nm, preferably 0.5 to 80 nm, more preferably 1 to 70 nm, and further preferably 1 to 60 nm. Is.

The metal constituting the metal nanoparticles portion of the surface-modified metal nanoparticles (A) may be any metal having conductivity, for example, gold, silver, copper, nickel, aluminum, rhodium, cobalt, ruthenium and the like. Can be mentioned. Among the metal nanoparticles in the present invention, silver nanoparticles are particularly capable of forming conductive electronic components even on a general-purpose plastic substrate having low heat resistance by fusing to each other at a temperature of about 100 ° C. Is preferable. Therefore, the surface-modified metal nanoparticles in the present invention are preferably surface-modified silver nanoparticles, and the metal-plated layer-forming composition of the present invention is preferably a silver-plated layer-forming composition.

The organic protective agent constituting the surface-modified portion of the surface-modified metal nanoparticles (A) is at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group, and a thiol group. A compound having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group, and a thiol group is preferable, and a compound having 4 to 18 carbon atoms is most preferable. It is preferably a compound having an amino group, and particularly preferably a compound having an amino group and having 4 to 18 carbon atoms (that is, an amine having 4 to 18 carbon atoms).

As the surface-modified metal nanoparticles (A), for example, surface-modified silver nanoparticles can be produced by a production method described later or the like.

(Dispersion medium (B))
The dispersion medium (B) in the present invention is a dispersion medium for dispersing the surface-modified metal nanoparticles (A). The dispersion medium (B) contains at least an alcohol (b-1) and a hydrocarbon (b-2). The (b-1) and the (b-2) can each contain one type alone or in combination of two or more types. The above (b-1) and (b-2) may be liquid or solid at room temperature and normal pressure by themselves, but the dispersion medium (B) containing both of them is , A liquid dispersion medium (liquid dispersion medium) under normal temperature and pressure.

Since the composition for forming a metal plating layer of the present invention contains the above (b-1) and the above (b-2) in combination as the dispersion medium (B), the surface-modified metal nanoparticles (A) are dispersed. Excellent in properties and dispersion stability.

(Alcohol (b-1))
The (b-1) includes primary alcohols, secondary alcohols, and tertiary alcohols. In the present invention, the surface-modified metal nanoparticles (A) have low reactivity with the surface-modified portion, and the loss of the surface-modified portion can be suppressed. Therefore, the surface-modified metal nanoparticles (A) are dispersed. The property can be stably maintained for a long period of time, that is, the dispersion stability is excellent, and the sinterability of the metal nanoparticles is improved by rapidly evaporating even in the case of low-temperature sintering, that is, low-temperature baking. Secondary alcohols and / or tertiary alcohols are particularly preferred in that they can impart binding properties.

Further, the above (b-1) includes an aliphatic alcohol, an alicyclic alcohol, and an aromatic alcohol, and among them, the alicyclic type is excellent in the dispersibility of the surface-modified metal nanoparticles (A). Alcohols (ie, alcohols with an alicyclic structure) are preferred.

Therefore, as the above (b-1), an alicyclic secondary alcohol and / or an alicyclic tertiary alcohol is preferable.

The alicyclic alcohol includes a monocyclic alcohol and a polycyclic alcohol. In particular, the monocyclic alcohol is particularly excellent in dispersibility of the surface-modified metal nanoparticles (A), and has low viscosity and applicability. (In the case of coating by the inkjet printing method, it is preferable in that it is excellent in injection stability from the head nozzle).

The boiling point of (b-1) is preferably, for example, 130 ° C. or higher, more preferably 170 ° C. or higher, and particularly when the surface-modified metal nanoparticles (A) are contained in a high concentration (for example, (for example,). A) The content (when the metal element equivalent) is 45% by weight or more of the total amount of the composition for forming a metal plating layer) is preferably 185 ° C. or higher, more preferably 190 ° C. or higher. The upper limit of the boiling point is, for example, 300 ° C., preferably 250 ° C., particularly preferably 220 ° C. When the boiling point is 130 ° C. or higher, volatilization at the printing temperature can be suppressed, and excellent coatability (in the case of coating by the inkjet printing method, injection stability from the head nozzle) can be obtained. Further, when the boiling point is 300 ° C. or lower, it rapidly volatilizes even in the case of low-temperature sintering, and a sintered body having conductivity can be obtained. That is, it is excellent in low-temperature sinterability. On the other hand, if the boiling point is lower than the above range, the fluidity of the composition for forming a metal plating layer decreases at the time of coating, and it may be difficult to form a uniform coating film. For example, when applied by the inkjet printing method, the composition for forming a metal plating layer solidifies and easily adheres to the nozzle opening of the head, and especially when the injection is performed intermittently, the injection becomes unstable and the flight bends. As a result, it may be difficult to print a desired pattern with high accuracy, or the nozzle opening may be clogged and injection may not be possible.

Examples of the monocyclic secondary alcohol include cyclohexanol, 2-ethylcyclohexanol, 1-cyclohexanol, 3,5-dimethylcyclohexanol, 3,3,5-trimethylcyclohexanol, 2,3,5-. Trimethylcyclohexanol, 3,4,5-trimethylcyclohexanol, 2,3,4-trimethylcyclohexanol, 4- (tert-butyl) -cyclohexanol, 3,3,5,5-tetramethylcyclohexanol, 2- Cyclohexanol which may have a substituent such as isopropyl-5-methyl-cyclohexanol (= menthol) and the corresponding cyclohexanol are preferable, and cyclohexanol having an alkyl group having 1 to 3 carbon atoms is particularly preferable. Alternatively, cyclohexanol is preferable, and cyclohexanol having an alkyl group having 1 to 3 carbon atoms is particularly preferable.

Examples of the monocyclic tertiary alcohol include 1-methylcyclohexanol, 4-isopropyl-1-methylcyclohexanol, 2-cyclohexyl-2-propanol, 2- (4-methylcyclohexyl) -2-propanol and the like. , A tertiary alcohol having a 6-7 membered ring (particularly cyclohexane ring) structure is preferred.

As the (b-1), in particular, containing at least a secondary alcohol (particularly, a monocyclic secondary alcohol) is excellent in the initial dispersibility of the surface-modified metal nanoparticles (A) and is excellent. It is preferable in that the dispersibility can be maintained stably for a long period of time. The content of the secondary alcohol is preferably, for example, 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight, based on the total amount of (b-1). % Or more. The upper limit is 100% by weight.

(Hydrocarbon (b-2))
The above (b-2) includes aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. In the present invention, aliphatic hydrocarbons and / or alicyclic hydrocarbons are particularly preferable in that the surface-modified metal nanoparticles (A) are particularly excellent in dispersibility.

For the same reason as in (b-1), the boiling point of (b-2) is preferably, for example, 130 ° C. or higher, more preferably 170 ° C. or higher, still more preferably 190 ° C. or higher, and particularly the surface. When the modified metal nanoparticles (A) are contained in a high concentration (for example, when the content (A) (in terms of metal element) is 45% by weight or more of the total amount of the composition for forming a metal plating layer), the temperature is 200 ° C. The above is preferable, more preferably 230 ° C. or higher, particularly preferably 250 ° C. or higher, and most preferably 270 ° C. or higher. The upper limit of the boiling point is, for example, 300 ° C.

Examples of the aliphatic hydrocarbon include n-decane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane and the like having 10 carbon atoms. Above (for example, 10 to 20), in particular, a chain having 12 or more carbon atoms (for example, 12 to 20, preferably 12 to 18), particularly 15 or more carbon atoms (for example, 15 to 20, preferably 15 to 18). Aliphatic hydrocarbons are preferred.

Examples of the alicyclic hydrocarbon include monocyclic compounds such as cyclohexanes, cyclohexenes, terpene-based 6-membered ring compounds, cycloheptene, cycloheptene, cyclooctane, cyclooctene, cyclodecane, and cyclododecene; bicyclo [2.2. 2] Polycyclic compounds such as octane and decalin can be mentioned.

The cyclohexanes include, for example, ethylcyclohexane, n-propylcyclohexane, isopropylcyclohexane, n-butylcyclohexane, isobutylcyclohexane, sec-butylcyclohexane, tert-butylcyclohexane, and other 6-membered rings with 2 or more carbon atoms (for example, 2). ~ 5) Compound having an alkyl group; Bicyclohexyl and the like are included.

The terpene-based 6-membered ring compound includes, for example, α-pinene, β-pinene, limonene, α-terpinene, β-terpinene, γ-terpinene, terpinene and the like.

The (b-2) preferably contains at least an aliphatic hydrocarbon (particularly preferably a chain aliphatic hydrocarbon, most preferably a chain aliphatic hydrocarbon having 15 or more carbon atoms). The content of the aliphatic hydrocarbon is preferably, for example, 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight, based on the total amount of (b-2). % Or more. The upper limit is 100% by weight.

((Meta) Acrylate (C))
The composition for forming a metal plating layer of the present invention contains (meth) acrylate (C) in an amount of 4 to 10 parts by weight based on 100 parts by weight of the component (A). Therefore, excellent substrate adhesion (particularly, adhesion to a smooth substrate such as a glass substrate) can be imparted to the sintered body of the composition for forming a metal plating layer without impairing the coatability. In the present specification, "(meth) acrylate" means "acrylate" and "methacrylate", and "(meth) acryloyl" means "acryloyl" and "methacryloyl".

As the (meth) acrylate (C), a compound having two or more (meth) acryloyl groups in one molecule, that is, a polyfunctional (meth) acrylate is preferable.

The molecular weight of the (meth) acrylate (C) (polystyrene-equivalent molecular weight by GPC, weighted average value of the molecular weight when two or more compounds are contained as the (meth) acrylate (C)) is, for example, 500 to 10000. It is preferably 750 to 5000, and particularly preferably 1000 to 2000. When the molecular weight of the (meth) acrylate (C) is 500 or more, the substrate adhesion to the sintered body of the composition for forming a metal plating layer containing the (meth) acrylate (C) is excellent (particularly, a glass substrate or the like). Adhesion to smoothing groups) can be imparted. When the molecular weight of the (meth) acrylate (C) is 10,000 or less, the composition for forming a metal plating layer containing the (meth) acrylate (C) has good coatability.

When the molecular weight of the (meth) acrylate (C) exceeds the above range, the solubility in the dispersion medium (B) tends to decrease, and even if it is dissolved in the dispersion medium (B), good coatability can be obtained. It tends to be difficult. Further, the (meth) acrylate (C) having a molecular weight lower than the above range tends to be difficult to obtain the effect of imparting substrate adhesion even when added to the composition for forming a metal plating layer.

The (meth) acryloyl equivalent of the (meth) acrylate (C) [when two or more compounds are contained as the (meth) acrylate (C), the weighted average value of the (meth) acryloyl equivalent] is, for example, 250 to 5000 g. / Eq, preferably 300 to 3000 g / eq, more preferably 450 to 3000 g / eq, particularly preferably 500 to 2500 g / eq, most preferably 600 to 2500 g / eq. When the (meth) acryloyl equivalent exceeds the above range, it tends to be difficult to obtain sufficient substrate adhesion. Further, when the (meth) acryloyl equivalent is less than the above range, low-temperature sintering becomes difficult and the conductivity tends to decrease.

The glass transition temperature (Tg) of the (meth) acrylate (C) is, for example, preferably −70 ° C. to 0 ° C., more preferably −60 ° C. to −10 ° C., and further preferably −60 ° C. to −20 ° C. .. The glass transition temperature (Tg) of the (meth) acrylate (C) can be measured by, for example, differential scanning calorimetry (DSC), dynamic viscoelasticity measurement, or the like.

As the (meth) acrylate, urethane (meth) acrylate is preferable in terms of solubility in the dispersion medium (B).

The urethane (meth) acrylate is a urethane compound having (meth) acryloyl groups at both ends, which is obtained by reacting a hydroxy (meth) acrylate with a terminal isocyanate group of an addition reaction product of a polyol and a polyisocyanate.

The urethane (meth) acrylate includes an aliphatic urethane (meth) acrylate and an aromatic urethane (meth) acrylate, and among them, the aliphatic urethane (meth) acrylate suppresses aggregation between metal nanoparticles. It is preferable because it has an excellent effect.

The polyol includes, for example, an aliphatic polyol, an alicyclic polyol, and an aromatic polyol, and among them, an aliphatic or alicyclic polyol is preferable. Further, the polyol includes polyester polyol, polyether polyol, polycarbonate polyol, low molecular weight glycol and the like.

Examples of the polyester polyol include dicarboxylic acids (for example, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, and 1,4-cyclohexane. Dicarboxylic acid, etc.) and diols (eg, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Hexanediol, neopentyl glycol, trimethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1 , 3-Propanediol, 2-methyl-1,3-propanediol and other aliphatic diols; 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A and other alicyclic diols, etc.) Reactants of.

Examples of the polyether polyol include alkylenes of compounds having two or more hydroxyl groups (for example, polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, etc.). Examples thereof include poly (oxyalkylene) glycol which is an oxide (for example, ethylene oxide, propylene oxide, butylene oxide, etc.) addition polymer.

Examples of the polycarbonate polyol include diols (for example, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.) and dimethyl carbonate. And reaction products with phosgen and the like.

Examples of the low molecular weight glycol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6. -Hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propane Aliper diols such as diols, 2-methyl-1,3-propanediol; alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and bisphenol A hydride; Examples thereof include trifunctional or higher functional hydroxyl group-containing compounds such as pentaerythritol.

The polyisocyanate includes an aliphatic polyisocyanate, an alicyclic polyisocyanate, and an aromatic polyisocyanate, and among them, an aliphatic or alicyclic polyisocyanate is preferable. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate. Examples of the alicyclic polyisocyanate include isophorone diisocyanate.

Examples of the hydroxy (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and pentaerythritol tri. Examples include acrylate.

As the urethane (meth) acrylate, for example, commercially available products such as trade names "EBECRYL 230" and "EBECRYL 270" (all manufactured by Daicel Ornex Co., Ltd.) can be preferably used.

(Thermal Radical Polymerization Initiator (D))
The composition for forming a metal plating layer of the present invention contains a thermal radical polymerization initiator (D) together with (meth) acrylate (C). The thermal radical polymerization initiator (D) includes azo compounds such as azobisisobutyronitrile and organic peroxides. In the present invention, organic peroxides can be used. It is preferable from the viewpoint of the dispersibility of the metal nanoparticles and the fluidity of the composition for forming the metal plating layer.

On the other hand, in the azo compound, the unshared electron pair contained in the N atom in the compound acts on the metal nanoparticles in the same manner as the above-mentioned organic protective agent, so that the azo compound is used in the composition for forming a metal plating layer of the present invention. Is not preferable because the dispersibility of the metal nanoparticles tends to decrease, the viscosity increases, and the coatability tends to decrease. The proportion of the azo compound in the total amount (100% by weight) of the thermal radical polymerization initiator contained in the composition for forming a metal plating layer of the present invention is preferably, for example, 30% by weight or less, more preferably 20% by weight. Hereinafter, it is particularly preferably 10% by weight or less, and most preferably 1% by weight or less. The lower limit is zero.

Examples of the organic peroxides include hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxydicarbonate, peroxyketal, ketone peroxide and the like (specifically, benzoyl peroxide, etc.). tert-Butylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) peroxyhexane, tert-butylperoxybenzoate, tert-butyl peroxide, cumenhydro Peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-dibutylperoxyhexane, 2,4-dichlorobenzoyl peroxide, 1,4-di (2-tert-) Butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, methylethyl ketone peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethyl Hexanoate, etc.).

The composition for forming a metal plating layer of the present invention requires additives such as a dispersant, a surface energy adjusting agent, a plasticizer, a leveling agent, and a defoaming agent in addition to the above components (A) to (D). Can be contained according to the above.

(Manufacturing method of composition for forming metal plating layer)
The composition for forming a metal plating layer of the present invention is, for example, a step of mixing a metal compound and an organic protective agent to form a complex containing the metal compound and the organic protective agent (complex formation step), and heats the complex. The surface-modified metal nanoparticles (A) were produced through a step of decomposing (thermal decomposition step) and a step of cleaning the reaction product (cleaning step) as needed, and the obtained surface-modified metal nanoparticles (A) were produced. ), A step of mixing the dispersion medium (B) and the (meth) acrylate (C) (a step of preparing a composition for forming a metal plating layer).

(Complex formation step)
The complex formation step is a step of mixing a metal compound and an organic protective agent to form a complex containing the metal compound and the organic protective agent. In the present invention, when a silver compound is used as the metal compound, nano-sized silver particles are fused to each other at a temperature of about 100 ° C., so that they have conductivity even on a general-purpose plastic substrate having low heat resistance. It is preferable in that an electronic component can be formed, and in particular, it is preferable to use a silver compound which is easily decomposed by heating to produce metallic silver. Examples of such silver compounds include silver carboxylate such as silver formate, silver acetate, silver oxalate, silver malonate, silver benzoate, and silver phthalate; silver fluoride, silver chloride, silver bromide, and iodide. Silver halide such as silver; silver sulfate, silver nitrate, silver carbonate and the like can be mentioned. In the present invention, among them, the silver content is high, thermal decomposition can be performed without using a reducing agent, and impurities derived from the reducing agent are less likely to be mixed into the composition for forming a metal plating layer. Silver oxalate is preferred.

As an organic protective agent, the unshared electron pair in the hetero atom is coordinated with the metal nanoparticles, so that the effect of strongly suppressing the aggregation between the metal nanoparticles can be exerted. A compound having at least one functional group selected from the group consisting of a group, an amino group, a sulfo group and a thiol group is preferable, and a group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group and a thiol group is particularly preferable. A compound having 4 to 18 carbon atoms having at least one functional group selected from the above is preferable.

As the organic protective agent, a compound having an amino group is particularly preferable, and a compound having an amino group having 4 to 18 carbon atoms, that is, an amine having 4 to 18 carbon atoms is most preferable.

The amine is a compound in which at least one hydrogen atom of ammonia is substituted with a hydrocarbon group, and includes a primary amine, a secondary amine, and a tertiary amine. Further, the amine may be a monoamine or a polyvalent amine such as a diamine. These can be used alone or in combination of two or more.

Among them, the amine is represented by the following formula (a-1), and R ¹ , R ² , and R ³ in the formula are the same or different, and a hydrogen atom or a monovalent hydrocarbon group (R ¹ , R) is used. ⁽ Except when both 2 and R ³ are hydrogen atoms), monoamine (1) having a total carbon number of 6 or more, represented by the following formula (a-1), R ¹ , R ² in the formula A ^{monoamine (2) in which R 3} is the same or different, is a hydrogen atom or a monovalent hydrocarbon group ( ^{except when R 1} , R ² , and R ³ are all hydrogen atoms) and has a total carbon number of 5 or less. ) And the following formula (a-2), R ^{4 to} R ⁷ in the formula are the same or different, a hydrogen atom or a monovalent hydrocarbon group, and R ⁸ is a divalent hydrocarbon group. It preferably contains at least one selected from the hydrocarbons (3) having a total carbon number of 8 or less, and in particular, the monoamine (1) and the monoamine (2) and / or the diamine (3). It is preferable to contain them together.

The hydrocarbon group includes an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Among them, an aliphatic hydrocarbon group and an alicyclic hydrocarbon group are preferable, and a fat is particularly preferable. Group hydrocarbon groups are preferred. Therefore, as the monoamine (1), monoamine (2), and diamine (3), the aliphatic monoamine (1), the aliphatic monoamine (2), and the aliphatic diamine (3) are preferable.

Further, the monovalent aliphatic hydrocarbon group includes an alkyl group and an alkenyl group. The monovalent alicyclic hydrocarbon group includes a cycloalkyl group and a cycloalkenyl group. Further, the divalent aliphatic hydrocarbon group includes an alkylene group and an alkaneylene group, and the divalent alicyclic hydrocarbon group includes a cycloalkylene group and a cycloalkenylene group.

Examples of the monovalent hydrocarbon group in R ¹ , R ² and R ³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and a pentyl group. , Hexyl group, decyl group, dodecyl group, tetradecyl group, octadecyl group and other alkyl groups having about 1 to 18 carbon atoms; vinyl group, allyl group, metallicyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, An alkenyl group having about 2 to 18 carbon atoms such as 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 5-hexenyl group; cyclopropyl group, Cycloalkyl groups having about 3 to 18 carbon atoms such as cyclobutyl group, cyclopentyl group, cyclohexyl group and cyclooctyl group; cycloalkenyl groups having about 3 to 18 carbon atoms such as cyclopentenyl group and cyclohexenyl group can be mentioned. can.

Examples of the monovalent hydrocarbon group in R ^{4 to} R ⁷ include an alkyl group having about 1 to 7 carbon atoms, an alkenyl group having about 2 to 7 carbon atoms, and a cyclo having about 3 to 7 carbon atoms in the above examples. Examples thereof include an alkyl group and a cycloalkenyl group having about 3 to 7 carbon atoms.

Examples of the divalent hydrocarbon group in R ⁸ include a methylene group, a methylmethylene group, a dimethylmethylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a heptamethylene group and the like having 1 carbon number. Alkylene group of ~ 8; alkenylene group having 2 to 8 carbon atoms such as vinylene group, propenylene group, 1-butenylene group, 2-butenylene group, butadienylene group, pentenylene group, hexenylene group, heptenylene group, octenylene group and the like. Can be done.

The ^{hydrocarbon groups in R 1 to} R ⁸ are various substituents [for example, halogen atom, oxo group, hydroxyl group, substituted oxy group (for example, C _1-4 alkoxy group, C _6-10 aryloxy group, C). _7-16 aralkyloxy group, C _1-4 acyloxy group, etc.), carboxyl group, substituted oxycarbonyl group (eg, C _1-4 alkoxycarbonyl group, C _6-10 aryloxycarbonyl group, C _7-16 aralkyloxycarbonyl) Group, etc.), cyano group, nitro group, sulfo group, heterocyclic group, etc.] may be used. Further, the hydroxyl group and the carboxyl group may be protected by a protecting group commonly used in the field of organic synthesis.

The monoamine (1) is a compound having a function of suppressing aggregation and enlargement of metal nanoparticles by adsorbing on the surface of the metal nanoparticles, that is, imparting high dispersibility to the metal nanoparticles. , For example, primary amines having linear alkyl groups such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine; Primary amines with branched chain alkyl groups such as isohexylamine, 2-ethylhexylamine, tert-octylamine; primary amines with cycloalkyl groups such as cyclohexylamine; primary amines with alkenyl groups such as oleylamine. Secondary amines, etc .; N, N-dipropylamine, N, N-dibutylamine, N, N-dipentylamine, N, N-dihexylamine, N, N-dipeptylamine, N, N-dioctylamine, N, N- Secondary amines with linear alkyl groups such as dinonylamine, N, N-didecylamine, N, N-diundesylamine, N, N-didodecylamine, N-propyl-N-butylamine; N, N-di Secondary amines with branched alkyl groups such as isohexylamines, N, N-di (2-ethylhexyl) amines; tertiary amines with linear alkyl groups such as tributylamines and trihexylamines; tri Examples thereof include tertiary amines having a branched alkyl group such as isohexylamine and tri (2-ethylhexyl) amine.

Among the above monoamines (1), when the amino group is adsorbed on the surface of the metal nanoparticles, the distance from other metal nanoparticles can be secured, so that the effect of preventing aggregation of the metal nanoparticles can be obtained and sintering is performed. Amines having a linear alkyl group with a total carbon number of 6-18 (upper limit of total carbon number is more preferably 16, particularly preferably 12), sometimes easily removed, (particularly primary amines). ) Is preferable, and n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine and the like are particularly preferable.

Since monoamine (2) has a shorter hydrocarbon chain than monoamine (1), it has a low function of imparting high dispersibility to metal nanoparticles by itself, but it has higher polarity than monoamine (1) and becomes a metal atom. Because of its high coordination ability, it has a complex formation promoting effect. Further, since the hydrocarbon chain is short, it can be removed from the surface of the metal nanoparticles in a short time (for example, 30 minutes or less, preferably 20 minutes or less) even in low temperature sintering, and a sintered body having excellent conductivity can be obtained. can get.

Examples of the monoamine (2) include total carbon having a linear or branched alkyl group such as n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, isopentylamine, and tert-pentylamine. A primary amine having a number of 2 to 5 (preferably a total carbon number of 4 to 5) and a total carbon number of 2 to 5 (preferably a total carbon number) having a linear or branched alkyl group such as N, N-diethylamine. Secondary amines of equations 4-5) can be mentioned. In the present invention, a primary amine having a linear alkyl group and having a total carbon number of 2 to 5 (preferably a total carbon number of 4 to 5) is preferable.

Since the total carbon number of the diamine (3) is 8 or less, the polarity is higher than that of the monoamine (1), and the coordination ability to the metal atom is high, the diamine (3) has a complex formation promoting effect. Further, the diamine (3) has an effect of accelerating the thermal decomposition at a lower temperature and in a short time in the thermal decomposition step of the complex, and the use of the diamine (3) makes the production of surface-modified metal nanoparticles more efficient. Can be done. Further, the surface-modified metal nanoparticles having a structure coated with a protective agent containing diamine (3) exhibit excellent dispersion stability in a highly polar dispersion medium. Further, since the diamine (3) has a short hydrocarbon chain, it can be removed from the surface of metal nanoparticles in a short time (for example, 30 minutes or less, preferably 20 minutes or less) even in low temperature sintering, and it becomes conductive. An excellent sintered body can be obtained.

Examples of the diamine (3) include 2,2-dimethyl-1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, and 1,7-heptandiamine. , 1,8-octanediamine, 1,5-diamino-2-methylpentane, etc., R ^{4 to} R ⁷ in the formula (a-2) are hydrogen atoms, and R ⁸ is linear or branched. Diamine which is an alkylene group; N, N'-dimethylethylenediamine, N, N'-diethylethylenediamine, N, N'-dimethyl-1,3-propanediamine, N, N'-diethyl-1,3-propanediamine, In formula (a-2) of N, N'-dimethyl-1,4-butanediamine, N, N'-diethyl-1,4-butanediamine, N, N'-dimethyl-1,6-hexanediamine, etc. R ⁴ and R ⁶ are the same or different linear or branched alkyl groups, R ⁵ and R ⁷ are hydrogen atoms, and R ⁸ is a linear or branched alkylene group. N, N-dimethylethylenediamine, N, N-diethylethylenediamine, N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, N, N-dimethyl-1,4- butanediamine, N, N-diethyl-1,4-butanediamine, N, N-dimethyl -1,6- R ^4, R ⁵ are the same or different and straight-chain in the formula (a-2), such as hexanediamine Examples thereof include diamine, which is a linear or branched alkyl group, R ⁶ and R ⁷ are hydrogen atoms, and R ⁸ is a linear or branched alkylene group.

^{Among these, R 4} and R ⁵ in the above formula (a-2) are the same or different linear or branched alkyl groups, R ⁶ and R ⁷ are hydrogen atoms, and R ⁸ is. Diamine which is a linear or branched alkylene group [In particular, R ⁴ and R ⁵ in the formula (a-2) are linear alkyl groups, R ⁶ and R ⁷ are hydrogen atoms, and R ⁸ Is a linear alkylene group, diamine] is preferable.

^{Diamines in which R 4} and R ⁵ in the formula (a-2) are the same or different linear or branched alkyl groups and R ⁶ and R ⁷ are hydrogen atoms, that is, primary amino groups and the first A diamine having a tertiary amino group is a complex formed because the primary amino group has a high coordinating ability with respect to a metal atom, but the tertiary amino group has a poor coordinating ability with respect to a metal atom. Is prevented from becoming excessively complicated, which enables thermal decomposition at a lower temperature and in a shorter time in the thermal decomposition step of the complex. Among these, diamines having a total carbon number of 6 or less (for example, 1 to 6, preferably 4 to 6) are preferable, and diamines having a total carbon number of 5 or less (for example, 1 to 6, preferably 4 to 6) are preferable because they can be removed from the surface of metal nanoparticles in a short time by low-temperature sintering. For example, diamines of 1 to 5, preferably 4 to 5) are more preferable.

The proportion of the content of the monoamine (1) in the total amount of the organic protective agent contained in the composition for forming the metal plating layer of the present invention and the proportion of the total content of the monoamine (2) and the diamine (3) are as follows. It is preferably in the range.
Content of monoamine (1): For example, 5 to 65 mol% (the lower limit is preferably 10 mol%, particularly preferably 20 mol%, most preferably 30 mol%, and the upper limit is preferably 60 mol%. , Particularly preferably 50 mol%)
Total content of monoamine (2) and diamine (3): for example 35-95 mol% (lower limit is preferably 40 mol%, particularly preferably 50 mol%, and upper limit is preferably 90 mol%, Especially preferably 80 mol%, most preferably 70 mol%)

The proportion of the content of the monoamine (2) and the proportion of the content of the diamine (3) in the total amount of the organic protective agent contained in the composition for forming the metal plating layer of the present invention are preferably in the following ranges. ..
Content of monoamine (2): For example, 5 to 65 mol% (the lower limit is preferably 10 mol%, particularly preferably 20 mol%, most preferably 30 mol%, and the upper limit is preferably 60 mol%. , Particularly preferably 50 mol%)
Content of diamine (3): for example 5 to 50 mol% (the lower limit is preferably 10 mol%, and the upper limit is preferably 40 mol%, particularly preferably 30 mol%).

By containing the monoamine (1) in the above range, the dispersion stability of the metal nanoparticles can be obtained. When the content of the monoamine (1) is less than the above range, the metal nanoparticles tend to agglomerate easily. On the other hand, when the content of the monoamine (1) exceeds the above range, it becomes difficult to remove the amine from the surface of the metal nanoparticles in a short time when the sintering temperature is low, and the conductivity of the obtained sintered body is lowered. Tend to do.

By containing the monoamine (2) in the above range, a complex formation promoting effect can be obtained. Further, even if the sintering temperature is low, the organic protective agent can be removed from the surface of the metal nanoparticles in a short time.

By containing the diamine (3) in the above range, the complex formation promoting effect and the thermal decomposition promoting effect of the complex can be easily obtained. Further, the surface-modified metal nanoparticles having a structure coated with a protective agent containing diamine (3) exhibit excellent dispersion stability in a highly polar dispersion medium.

In the present invention, when monoamine (2) and / or diamine (3) having a high coordinating ability to a metal atom of a metal compound is used, the amount of monoamine (1) used is reduced according to the ratio of their use. It is preferable in that the organic protective agent can be removed from the surface of the metal nanoparticles in a short time even if the sintering temperature is low.

The amine used as the organic protective agent in the present invention may contain other amines in addition to the above monoamines (1), monoamines (2), and diamines (3), but all of them are contained in the organic protective agent. The ratio of the total content of the monoamine (1), monoamine (2), and diamine (3) to the amine is preferably, for example, 60% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more. Is. The upper limit is 100% by weight. That is, the content of the other amine is preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less.

The amount of the organic protective agent [particularly monoamine (1) + monoamine (2) + diamine (3)] used is not particularly limited, but is about 1 to 50 mol with respect to 1 mol of the metal atom of the metal compound as a raw material. It is preferably, particularly preferably 2 to 50 mol, most preferably 6 to 50 mol. If the amount of the organic protective agent used is less than the above range, the metal compound that is not converted into the complex tends to remain in the complex formation step, and it tends to be difficult to impart sufficient dispersibility to the metal nanoparticles. ..

In the present invention, for the purpose of further improving the dispersibility of metal nanoparticles, as an organic protective agent, a compound having an amino group and a compound having a carboxyl group (for example, a compound having a carboxyl group and having 4 to 18 carbon atoms) are used. , Preferably an aliphatic monocarboxylic acid having 4 to 18 carbon atoms) may be contained alone or in combination of two or more.

Examples of the aliphatic monocarboxylic acid include butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid and hexadecanoic acid. Saturated aliphatic monocarboxylic acid having 4 or more carbon atoms such as heptadecanoic acid, octadecanoic acid, nonadecanoic acid and icosanoic acid; Monocarboxylic acids can be mentioned.

Among these, saturated or unsaturated aliphatic monocarboxylic acids having 8 to 18 carbon atoms (particularly, octanoic acid, oleic acid, etc.) are preferable. When the carboxyl group of the aliphatic monocarboxylic acid is adsorbed on the surface of the metal nanoparticles, the saturated or unsaturated aliphatic hydrocarbon chain having 8 to 18 carbon atoms becomes a steric obstacle, so that the distance from the other metal nanoparticles Can be ensured, and the action of preventing aggregation of metal nanoparticles is improved.

The amount of the compound having a carboxyl group to be used is, for example, about 0.05 to 10 mol, preferably 0.1 to 5 mol, particularly preferably 0.5 to 2 mol, with respect to 1 mol of the metal atom of the metal compound. Is. If the amount of the compound having a carboxyl group used is less than the above range, it is difficult to obtain the effect of improving the dispersion stability. On the other hand, even if the compound having a carboxyl group is excessively used, the effect of improving the dispersion stability is saturated, but it tends to be difficult to remove it by low-temperature sintering.

The reaction between the organic protective agent and the metal compound is carried out in the presence or absence of a dispersion medium. As the dispersion medium, for example, an alcohol having 3 or more carbon atoms can be used.

Examples of the alcohol having 3 or more carbon atoms include n-propanol (boiling point: 97 ° C.), isopropanol (boiling point: 82 ° C.), n-butanol (boiling point: 117 ° C.), and isobutanol (boiling point: 107.89 ° C.). , Se-butanol (boiling point: 99.5 ° C), tert-butanol (boiling point: 82.45 ° C), n-pentanol (boiling point: 136 ° C), n-hexanol (boiling point: 156 ° C), n-octanol (boiling point: 156 ° C) Boiling point: 194 ° C.), 2-octanol (boiling point: 174 ° C.) and the like. Among these, alcohols having 4 to 6 carbon atoms are preferable, and in particular, alcohols having 4 to 6 carbon atoms are preferable in terms of being able to set a high temperature in the subsequent thermal decomposition step of the complex and being convenient in the post-treatment of the obtained surface-modified metal nanoparticles. n-butanol and n-hexanol are preferable.

The amount of the dispersion medium used is, for example, 120 parts by weight or more, preferably 130 parts by weight or more, and more preferably 150 parts by weight or more with respect to 100 parts by weight of the metal compound. The upper limit of the amount of the dispersion medium used is, for example, 1000 parts by weight, preferably 800 parts by weight, and particularly preferably 500 parts by weight.

The reaction between the organic protective agent and the metal compound is preferably carried out at room temperature (5 to 40 ° C.). Since the reaction is accompanied by heat generation due to the coordination reaction of the organic protective agent with the metal compound, it may be carried out while appropriately cooling so as to be within the above temperature range.

The reaction time between the organic protective agent and the metal compound is, for example, about 30 minutes to 3 hours. As a result, a metal-organic protective agent complex (when amine is used as the organic protective agent, a metal-amine complex) is obtained.

(Pyrolysis process)
The thermal decomposition step is a step of thermally decomposing the metal-organic protective agent complex obtained through the complex formation step to form surface-modified metal nanoparticles. By heating the metal-organic protective agent complex, the metal compound thermally decomposes to form metal atoms while maintaining the coordination bond of the organic protective agent to the metal atoms, and then the organic protective agent coordinates. It is considered that the metal atoms formed are aggregated to form metal nanoparticles coated with an organic protective film.

The thermal decomposition is preferably carried out in the presence of a dispersion medium, and the above-mentioned alcohol can be preferably used as the dispersion medium. The thermal decomposition temperature may be any temperature at which surface-modified metal nanoparticles are formed, and when the metal-organic protective agent complex is a silver oxalate-organic protective agent complex, for example, about 80 to 120 ° C. The temperature is preferably 95 to 115 ° C, particularly preferably 100 to 110 ° C. From the viewpoint of preventing detachment of the surface-modified portion of the surface-modified metal nanoparticles, it is preferable to carry out the process at a temperature as low as possible within the above temperature range. The thermal decomposition time is, for example, about 10 minutes to 5 hours.

Further, the thermal decomposition of the metal-organic protective agent complex is preferably carried out in an air atmosphere or an atmosphere of an inert gas such as argon.

(Washing process)
After the completion of the thermal decomposition reaction of the metal-organic protective agent complex, if excess organic protective agent is present, it is preferable to repeat decantation once or twice or more in order to remove it. Further, the surface-modified metal nanoparticles after the decantation can be subjected to the preparation step of the composition for forming a metal plating layer described later in a wet state without being dried and solidified. It is preferable in that aggregation can be suppressed and high dispersibility can be maintained.

Decantation is performed, for example, by washing suspended surface-modified metal nanoparticles with a detergent, precipitating the surface-modified metal nanoparticles by centrifugation, and removing the supernatant. As the cleaning agent, for example, one or more linear or branched alcohols having 1 to 4 carbon atoms (preferably 1 to 2) such as methanol, ethanol, n-propanol, and isopropanol are used. This is preferable in that the surface-modified metal nanoparticles have good sedimentation property and the cleaning agent can be efficiently separated and removed by centrifugation after cleaning.

(Preparation process of composition for forming metal plating layer)
The step of preparing the composition for forming the metal plating layer includes the surface-modified metal nanoparticles (A) (preferably the wet surface-modified metal nanoparticles (A)) and the dispersion medium (B) obtained through the above steps. This is a step of preparing the composition for forming a metal plating layer of the present invention by mixing (meth) acrylate (C) and, if necessary, an additive. For the mixing, for example, a commonly known mixing device such as a self-revolving stirring and defoaming device, a homogenizer, a planetary mixer, a three-roll mill, and a bead mill can be used. Further, each component may be mixed at the same time or sequentially. The blending ratio of each component can be appropriately adjusted within the following range.

The content (metal element equivalent) of the surface-modified metal nanoparticles (A) in the total amount (100% by weight) of the composition for forming a metal plating layer of the present invention is, for example, about 35 to 70% by weight. The lower limit is preferably 40% by weight, particularly preferably 45% by weight, most preferably 50% by weight, and particularly preferably 55% by weight, from the viewpoint of obtaining a coating film or a sintered body having a higher film thickness. The upper limit is preferably 65% by weight, particularly preferably 60% by weight, from the viewpoint of coatability (in the case of coating by the inkjet printing method, injection stability from the head nozzle).

The content of the dispersion medium (B) (in terms of metal element) in the composition for forming a metal plating layer of the present invention is 20 to 100 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the surface-modified metal nanoparticles (A). It is 30 to 90 parts by weight, more preferably 40 to 80 parts by weight, still more preferably 50 to 75 parts by weight, particularly preferably 55 to 75 parts by weight, and most preferably 60 to 75 parts by weight.

The content of the dispersion medium (B) in the total amount (100% by weight) of the composition for forming a metal plating layer of the present invention is, for example, 20 to 65% by weight, preferably 25 to 60% by weight, and more preferably 30 to 55% by weight. %, Most preferably 30 to 50% by weight. The composition for forming a metal plating layer of the present invention has excellent coatability because it contains the dispersion medium (B) in the above range. For example, when coated by an inkjet printing method, the ejection stability from the nozzle of the head is good. Can be maintained at.

The content of (b-1) (particularly, monocyclic secondary alcohol) is, for example, 15 to 70 parts by weight, preferably 20 to 60 parts by weight, based on 100 parts by weight of the surface-modified metal nanoparticles (A). , Particularly preferably 30 to 55 parts by weight, most preferably 40 to 55 parts by weight.

The content of (b-2) (particularly an aliphatic hydrocarbon) is, for example, 5 to 50 parts by weight, preferably 10 to 40 parts by weight, particularly preferably 10 parts by weight, based on 100 parts by weight of the surface-modified metal nanoparticles (A). Is 15 to 30 parts by weight, most preferably 15 to 25 parts by weight.

The ratio of the content of the (b-1) to the content of the (b-2) in the total amount of the dispersion medium (B) contained in the composition for forming a metal plating layer of the present invention (the former / the latter (weight ratio)) is For example, 50/50 to 95/5, preferably 60/40 to 90/10, particularly preferably 65/35 to 85/15. When the content of (b-1) is less than the above range, the smoothness of the coating film tends to decrease. In addition, the low-temperature sinterability tends to decrease. On the other hand, when the content of (b-2) is less than the above range, the coatability tends to decrease.

The dispersion medium (B) in the present invention may contain one or more other dispersion media in addition to the above (b-1) and (b-2), but the above (b-). The total content of 1) and (b-2) is preferably 70% by weight or more, particularly preferably 75% by weight or more, and most preferably 80% by weight or more of the total amount of (B). Therefore, the content of the other dispersion medium (the total amount when two or more kinds are contained) is preferably 30% by weight or less, particularly preferably 25% by weight or less, and most preferably 20% by weight of the total amount of (B). % Or less. When the content of the other dispersion medium exceeds the above range, the coatability tends to decrease due to the thickening, or the metal nanoparticles tend to aggregate and the dispersibility tends to decrease.

Further, the content of the primary alcohol in the total amount (100% by weight) of the dispersion medium (B) contained in the composition for forming a metal plating layer of the present invention is preferably, for example, about 30% by weight or less, more preferably. It is preferably 25% by weight or less, particularly preferably 20% by weight or less, most preferably 15% by weight or less, and particularly preferably 5% by weight or less.

The content of (meth) acrylate (C) (particularly urethane (meth) acrylate) in the composition for forming a metal plating layer of the present invention is based on 100 parts by weight (metal element equivalent) of the surface-modified metal nanoparticles (A). The lower limit is preferably 5 parts by weight, particularly preferably 6 parts by weight, and most preferably 7 parts by weight. The upper limit is preferably 9 parts by weight. When the (meth) acrylate (C) is used in a range of 4 parts by weight or more, a sintered body having excellent substrate adhesion can be obtained. Further, when the (meth) acrylate (C) is used in the range of 10 parts by weight or less, a sintered body having conductivity can be obtained.

The (meth) acrylate (C) in the present invention includes other (meth) acrylates (for example, isobornyl (meth) acrylate, 1,6-hexanedimethanol di (meth) acrylate, etc. in addition to urethane (meth) acrylate. , (Meta) acrylate having a (meth) acryloyl equivalent of less than 250 g / eq) may be contained, but urethane in the total amount of (meth) acrylate (C) contained in the composition for forming a metal plating layer of the present invention. The proportion of the content of the (meth) acrylate is, for example, 50% by weight or more, preferably 55% by weight or more. Therefore, the content of the (meth) acrylate having a (meth) acryloyl equivalent of less than 250 g / eq is 50% by weight or less, preferably 45% by weight or less of the total amount of the (meth) acrylate (C).

Further, the composition for forming a metal plating layer of the present invention may contain other curable compounds in addition to (meth) acrylate (C), but is completely cured contained in the composition for forming a metal plating layer. The ratio of the (meth) acrylate (C) to the sex compound is, for example, 50% by weight or more, preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more. The upper limit is 100% by weight.

Further, the ratio of the total of the surface-modified metal nanoparticles (A), the dispersion medium (B) and the (meth) acrylate (C) to the total amount (100% by weight) of the composition for forming a metal plating layer of the present invention is, for example, It is 70% by weight or more, preferably 80% by weight or more, and particularly preferably 90% by weight or more.

The content of the thermal radical polymerization initiator (D) (the total amount when two or more kinds are contained) is, for example, 0.1 to 10 parts by weight, preferably 0, based on 100 parts by weight of the (meth) acrylate (C). .5 to 5.0 parts by weight, particularly preferably 1 to 5 parts by weight.

The viscosity (at 25 ° C., shear rate of 10 (1 / s)) of the composition for forming a metal plating layer of the present invention is, for example, 1 to 100 mPa · s. The upper limit of the viscosity is preferably 50 mPa · s, particularly preferably 20 mPa · s, and most preferably 15 mPa · s. The lower limit of the viscosity is preferably 2 mPa · s, particularly preferably 3 mPa · s, and most preferably 5 mPa · s.

The composition for forming a metal plating layer of the present invention has excellent dispersion stability. For example, when the composition for forming a metal plating layer having a metal concentration of 65% by weight is stored at 5 ° C., the metal nanoparticles are contained in a period of one month or more. Aggregation can be suppressed.

As described above, the composition for forming a metal plating layer of the present invention has a low viscosity and is excellent in coatability. In addition, the surface-modified metal nanoparticles (A) are excellent in dispersion stability, and good coatability can be maintained even if the surface-modified metal nanoparticles (A) are contained in a high concentration. Further, the composition for forming a metal plating layer of the present invention has excellent low-temperature sinterability, and a sintered body having excellent substrate adhesion can be obtained by low-temperature sintering. Furthermore, by sintering the composition for forming a metal plating layer of the present invention, a sintered body having conductivity can be obtained. Therefore, the composition for forming a metal plating layer of the present invention has high heat resistance such as a substrate (particularly, a substrate having low heat resistance such as a general-purpose plastic substrate or a glass substrate) by inkjet printing, gravure printing, or flexo printing. It can be suitably used for forming a metal plating layer on a substrate having a smooth surface and difficult to obtain an anchor effect).

[Method of forming metal plating layer]
The method for forming a metal plating layer of the present invention is characterized in that a metal plating layer is formed on a substrate by using a composition for forming a metal plating layer.

The thickness of the metal plating layer is preferably in the range of, for example, 0.1 to 5 μm (preferably 0.5 to 2 μm).

In the method for forming a metal plating layer of the present invention, since the composition for forming a metal plating layer is used, sintering is possible at a low temperature, and the sintering temperature is, for example, 150 ° C. or lower (the lower limit of the sintering temperature is For example, it is 60 ° C., more preferably 100 ° C. because it can be sintered in a short time), particularly preferably 130 ° C. or lower, and most preferably 120 ° C. or lower. The sintering time is, for example, 0.5 to 3 hours, preferably 0.5 to 2 hours, and particularly preferably 0.5 to 1 hour.

By using the composition for forming a metal plating layer of the present invention, the metal nanoparticles can be sufficiently sintered even at low temperature sintering (for example, sintering at low temperature for 30 minutes at 120 ° C. for a short time). proceed. As a result, a sintered body having excellent substrate adhesion (particularly, a sintered body having excellent adhesion to a substrate having excellent surface smoothness such as glass) can be obtained. Therefore, even if a protective film is attached to the surface of the sintered body for the purpose of preventing damage, for example, the sintered body will not be peeled off together when the protective film is peeled off.

Further, by sintering the composition for forming a metal plating layer of the present invention, a sintered body having conductivity can be obtained.

By using the composition for forming a metal plating layer of the present invention, a sintered body having excellent adhesion to a substrate can be obtained as described above. Therefore, as a substrate, the surface of a glass substrate or the like is smooth and has an anchor effect. Can be preferably used as a substrate for which it is difficult to obtain.

Further, as described above, low-temperature sintering is possible by using the composition for forming a metal plating layer of the present invention. Therefore, as the substrate, in addition to a glass substrate and a heat-resistant plastic substrate such as a polyimide film, polyethylene is used. A general-purpose plastic substrate having low heat resistance such as a polyester film such as a terephthalate (PET) film and a polyethylene naphthalate (PEN) film and a polyolefin film such as polypropylene can also be preferably used.

The substrate provided with the metal plating layer obtained by the method for forming the metal plating layer of the present invention includes, for example, a liquid crystal display, an organic EL display, a field emission display (FED), an IC card, an IC tag, a solar cell, an LED element, and an organic material. It is suitably used for transistors, capacitors, electronic paper, flexible batteries, flexible sensors, membrane switches, touch panels, EMI shields, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Preparation Example 1 (Preparation of surface-modified silver nanoparticles)
Complex formation step Silver oxalate (molecular weight: 303.78) was obtained from silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) and oxalic acid dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.).
20.0 g (65.8 mmol) of the silver oxalate was charged in a 500 mL flask, and 30.0 g of n-butanol was added thereto to prepare an n-butanol slurry of silver oxalate.
To this slurry, at 30 ° C., n-butylamine (molecular weight: 73.14, manufactured by Daicel Co., Ltd.) 57.8 g (790.1 mmol), n-hexylamine (molecular weight: 101.19, Tokyo Kasei Kogyo Co., Ltd.) 40.0 g (395.0 mmol), n-octylamine (molecular weight: 129.25, trade name "Farmin 08D", manufactured by Kao Co., Ltd.) 38.3 g (296.3 mmol), n-dodecylamine (molecular weight) 185.35, trade name "Farmin 20D", manufactured by Kao Co., Ltd. 18.3 g (98.8 mmol), and N, N-dimethyl-1,3-propanediamine (molecular weight: 102.18, Koei Chemical Industry Co., Ltd.) 40.4 g (395.0 mmol) of an amine mixed solution (manufactured by Co., Ltd.) was added dropwise.
After the dropping, the mixture was stirred at 30 ° C. for 2 hours to promote a complex formation reaction of silver oxalate and amine to obtain a white substance (silver oxalate-amine complex).

Pyrolysis step After the formation of the silver oxalate-amine complex, the temperature of the reaction solution is raised from 30 ° C. to about 105 ° C. (103 to 108 ° C.), and then heated for 1 hour while maintaining the above temperature. The silver acid-amine complex was thermally decomposed to obtain a suspension in which dark blue surface-modified silver nanoparticles were suspended in an amine mixture.

Washing step After cooling, 200 g of methanol is added to the obtained suspension and stirred, then surface-modified silver nanoparticles are precipitated by centrifugation, the supernatant is removed, and 60 g of methanol is added again and stirred. Then, the surface-modified silver nanoparticles were precipitated by centrifugation, and the supernatant was removed. In this way, wet surface-modified silver nanoparticles were obtained.

Example 1 (Preparation of composition for forming silver-plated layer)
Weigh each component according to the formulation (unit: parts by weight) shown in Table 1 below, stir in an oil bath (100 rpm) for 3 hours, and then use a rotating and revolving kneader (Mazelstar KKK2508, manufactured by Kurashiki Spinning Co., Ltd.). Stirring and kneading (2 minutes x 3 times) to form a black-brown silver-plated layer composition (1) (silver concentration: 50% by weight, viscosity (at 25 ° C., shear rate 10 (1 / s)): 10 .1 mPa · s) was obtained.
The obtained composition for forming a metal plating layer (1) is surface-modified silver by a dynamic light scattering method using the trade name "Zeta Nanosizer Series Nano-S" (manufactured by Malvern) as an analyzer. When the average particle size of the nanoparticles was confirmed, it was 25 nm.

Examples 2-4, Comparative Examples 1-3
A composition for forming a silver-plated layer (silver concentration: 50% by weight) was obtained in the same manner as in Example 1 except that the formulation was changed as shown in Table 1 below.

The substrate adhesion of the sintered body of the composition for forming a silver-plated layer obtained in Examples and Comparative Examples was evaluated by the following method.

(Evaluation of substrate adhesion of sintered body)
The composition for forming a silver plating layer obtained in Examples and Comparative Examples was applied onto a non-alkali glass plate to form a coating film. Using a hot plate, the obtained coating film is quickly sintered under condition 1 (100 ° C. for 30 minutes, 120 ° C. for 30 minutes) or condition 2 (100 ° C. for 30 minutes, 150 ° C. for 1 hour). Then, a sintered body having a thickness of about 1 μm was obtained.
A tape peeling test (based on JIS K 5600) was performed on the obtained sintered body / non-alkali glass plate laminate, and the ratio (residual rate) of the sintered body remaining on the non-alkali glass plate when the tape was peeled off. :%) Was used to evaluate the substrate adhesion.

<Surface-modified metal nanoparticles>
-Surface-modified silver nanoparticles: Surface-modified silver nanoparticles obtained in Preparation Example 1 <dispersion medium>
-Hexadecane: Boiling point 287 ° C, reagent manufactured by Tokyo Chemical Industry Co., Ltd.-3,3,5-trimethylcyclohexanol: Boiling point 193-196 ° C, reagent manufactured by Tokyo Chemical Industry Co., Ltd. <(meth) acrylate>
EBECRYL 230: Bifunctional aliphatic urethane acrylate, manufactured by Daicel Ornex Co., Ltd., molecular weight: 5000, acryloyl equivalent: 2500, Tg: -55 ° C, resin content 100% by weight
EBECRYL 270: Bifunctional aliphatic urethane acrylate, manufactured by Daicel Ornex Co., Ltd., molecular weight: 1500, acryloyl equivalent: 750, Tg: -27 ° C, resin content 100% by weight
EBECRYL 303: Bifunctional aliphatic urethane acrylate, manufactured by Daicel Ornex Co., Ltd., molecular weight: 900, containing 45% by weight of 1,6-hexanediol diacrylate in addition to 55% by weight of the resin component ・ EBECRYL 767: 2 Functional aliphatic urethane acrylate, manufactured by Daicel Ornex Co., Ltd., molecular weight: 1500, contains 30% by weight of isobornyl acrylate in addition to 70% by weight of the resin component <thermal radical polymerization initiator>
Perbutyl O: tert-butylperoxy-2-ethylhexanoate, manufactured by NOF CORPORATION, heat generation start temperature 106 ° C

Claims (13)

It contains the following components (A), (B), (C), and (D), the component (B) is 20 to 100 parts by weight with respect to 100 parts by weight of the component (A), and the component (C) is (A). It contains 4 to 10 parts by weight with respect to 100 parts by weight of the component, and the ratio of the contents of the following (b-1) and the following (b-2) (former / latter (weight ratio)) is 65/35 to 95/5. A composition for forming a metal plating layer.
Component (A): Surface-modified metal nanoparticles having a structure in which the surface of the metal nanoparticles is coated with an organic protective agent (B) Component: Monocyclic secondary alcohol (b-1) and chain aliphatic hydrocarbons Dispersion medium containing hydrogen (b-2) (C) component: Polyfunctional (meth) acrylate (however, the content of (meth) acrylate with a (meth) acryloyl equivalent of less than 250 g / eq is 50 in the total amount of component (C). Weight% or less)
Component (D): Thermal radical polymerization initiator According to claim 1, the organic protective agent constituting the component (A) is a compound having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group, and a thiol group. The composition for forming a metal plating layer according to the above. A compound having 4 to 18 carbon atoms, wherein the organic protective agent constituting the component (A) has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a sulfo group, and a thiol group. The composition for forming a metal plating layer according to claim 1. The metal according to claim 1, wherein the organic protective agent constituting the component (A) is an amine having 4 to 18 carbon atoms, or an amine having 1 to 18 carbon atoms and a fatty acid monocarboxylic acid having 1 to 18 carbon atoms. Composition for forming a plating layer. The composition for forming a metal plating layer according to any one of claims 1 to 4, wherein the (meth) acryloyl equivalent of the component (C) is 250 to 5000 g / eq. The composition for forming a metal plating layer according to any one of claims 1 to 5, wherein the polyfunctional (meth) acrylate is a polyfunctional urethane (meth) acrylate. The composition for forming a metal plating layer according to any one of claims 1 to 6, wherein the thermal radical polymerization initiator is an organic peroxide. The composition for forming a metal plating layer according to any one of claims 1 to 7, which has a viscosity (at 25 ° C. and a shear rate of 10 (1 / s)) of 1 to 100 mPa · s. The composition for forming a metal plating layer according to any one of claims 1 to 8, wherein the metal nanoparticles constituting the component (A) are silver nanoparticles. The composition for forming a metal plating layer according to any one of claims 1 to 9, which is used for forming a metal plating layer by inkjet printing, gravure printing, or flexographic printing. The composition for forming a metal plating layer according to any one of claims 1 to 10, which is used for forming a metal plating layer on a glass substrate. A method for forming a metal plating layer, wherein the metal plating layer is formed on a substrate by using the composition for forming a metal plating layer according to any one of claims 1 to 11. A substrate provided with a metal plating layer made of a sintered body of the composition for forming a metal plating layer according to any one of claims 1 to 11.