JPWO2019116978A1 - Metal ink, metal ink manufacturing method, and base material manufacturing method with metal pattern - Google Patents

Abstract

The metal ink applied on the substrate to form a metal pattern contains a metal colloid and a dispersion medium. The base material contains a thermoplastic resin at least in a region forming the metal pattern. The distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa0.5 or less, and the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa0.5 or more.

Description

The present invention relates to a metal ink containing a metal colloid and a method for producing the same, and a method for producing a base material having a metal pattern using the metal ink.

Metal inks containing metal nanoparticles are used to form metal patterns such as wiring patterns and conductive layers of electrodes. The metal ink is applied to the surface of the base material when forming the metal pattern. A resin film or the like is formed on the surface of the base material (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-22158

If the metal pattern can be formed directly on the base material formed of various thermoplastic resins, the step of coating the base material surface with the resin film can be omitted, which is convenient. However, many thermoplastic resins have low solvent resistance and are easily dissolved by the dispersion medium contained in the metal ink. When the base material is dissolved by the metal ink, the resistance is increased, the accuracy of the metal pattern is lowered, and the product is defective. On the other hand, if a dispersion medium that does not dissolve the thermoplastic resin is used, the stability of the metal colloid in the metal ink is lowered.

One aspect of the present invention is a metal ink that is applied onto a substrate to form a metal pattern.
Contains metal colloids and dispersion media
The base material contains a thermoplastic resin at least in a region forming the metal pattern.
The distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less.
The present invention relates to a metal ink in which the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more.

Another aspect of the present invention is a method for producing a metal ink containing a metal colloid and a dispersion medium and being applied onto a substrate to form a metal pattern.
The base material contains a thermoplastic resin at least in a region forming the metal pattern.
Prepare the dispersion medium in which the distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less, and the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. And the process to do
The present invention relates to a method for producing a metal ink, which comprises a step of preparing a metal ink in which the metal colloid is dispersed in the dispersion medium.

Yet another aspect of the present invention comprises a step of applying a metal ink onto a substrate to form a metal pattern.
The base material contains a thermoplastic resin at least in a region forming the metal pattern.
The metal ink contains a metal colloid and a dispersion medium.
The distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less.
The present invention relates to a method for producing a base material having a metal pattern, wherein the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more.

High stability of the metal colloid in the metal ink can be ensured, and dissolution of the base material can be suppressed when a metal pattern is formed using the metal ink on the region containing the thermoplastic resin of the base material.

Although the novel features of the present invention are described in the appended claims, the present invention is further described in the following detailed description collating the drawings with respect to both the structure and the content, together with the other objects and features of the present invention. It will be well understood.

In the metal ink used for forming the metal pattern, it is necessary to ensure the stability of the metal colloid (specifically, the dispersion stability) in the metal ink. On the other hand, in the electronics field, in recent years, a technique for forming a wiring pattern using a metal ink on a substrate made of a thermoplastic resin has been studied. However, the dispersion medium that easily secures the stability of the metal colloid easily dissolves the thermoplastic resin. Further, in the case of metal ink, it is necessary to adjust the affinity between the base material and the metal ink and the volatility of the dispersion medium contained in the metal ink in a well-balanced manner.

The metal ink according to one aspect of the present invention is a metal ink containing a metal colloid and a dispersion medium and applied on a base material to form a metal pattern. The base material contains a thermoplastic resin at least in a region forming a metal pattern. The distance Dc of the Hansen solubility parameter (HSP) between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less, and the distance Ds of the HSP between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. The solubility parameter represents a measure of affinity between substances, and HSP is represented by a three-dimensional vector of a dispersion term dD, a polar term dP, and a hydrogen bond term dH. Another aspect of the present invention also includes the use of the metal ink for coating on a substrate to form a metal pattern.

Such a metal ink is a step of preparing a dispersion medium in which the distance Dc of HSP between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less and the distance Ds of HSP between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. It can be produced by a production method including a step of preparing a metal ink in which a metal colloid is dispersed in a dispersion medium. Yet another aspect of the present invention also includes methods for producing such metal inks.

Another aspect of the present invention also includes a method of manufacturing a base material having a metal pattern, which comprises a step of applying a metal ink on the base material to form a metal pattern. Here, the base material contains a thermoplastic resin at least in a region forming a metal pattern. The metal ink contains a metal colloid and a dispersion medium. The distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less, and the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. Yet another aspect of the present invention also includes the use of the metal ink in a method of producing a substrate having a metal pattern.

According to the above aspect of the present invention, the distance Dc of HSP between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less, and the distance Ds of HSP between the dispersion medium and the base material (specifically, the thermoplastic resin) is 10 MPa. Adjust to ^0.5 or more. As a result, high stability of the metal colloid in the metal ink can be ensured, and dissolution of the base material when the metal ink is applied on the region containing the thermoplastic resin of the base material can be suppressed. By suppressing the dissolution of the base material (specifically, the thermoplastic resin) by the metal ink, it is possible to suppress the increase in the resistance of the metal pattern. Further, since the metal colloid in the metal ink has high stability, the metal ink can be stably stored for a long period of time. The metal colloid usually contains metal particles and a dispersant coordinated to the metal particles. In the above aspect of the present invention, the distance Dc is calculated based on the HSP of the metal colloid. As a result, a dispersion medium suitable for metal colloids can be obtained as compared with the case where the distance between the HSP of an organic group (hydrophobic group, etc.) having a low affinity for the metal particles of the dispersant or the dispersant and the HSP of the dispersion medium is used. Since it can be selected with high accuracy, high stability of the metal colloid in the metal ink can be ensured.

The distances Dc and Ds can be obtained as follows.
First, the sediment obtained by centrifuging the metal ink and the supernatant liquid are collected. The type of dispersion medium contained in the supernatant and the composition (mixing ratio in the case of a mixture) are determined by gas chromatography analysis. Then, from this kind and composition, the dispersion term dD, the polarity term dP, and the hydrogen bond term dH of the dispersion medium HSP are obtained using the HSP calculation software HSPiP (available from the official websites of HSP and HSPiP).

The HSP of the above-mentioned sediment (metal colloid) and base material (thermoplastic resin) can be determined by testing the solubility of each of the 23 types of media shown in Table 1.

Specifically, the HSP of the metal colloid is obtained as follows. The above sediment is added to each medium in Table 1 so as to have a concentration of 0.1% by mass, and the mixture is stirred with a roller shaker at room temperature (25 ° C.) for 10 minutes. After stirring, the mixture is allowed to stand at room temperature (25 ° C.) for 1 hour, and if the metal colloid is dispersed, it is set to 1, and if it is precipitated, it is set to 0. The HSP of each medium (that is, dD, dP and dH) is plotted three-dimensionally, and from the HSP distribution of the medium in which the metal colloid is dispersed, a sphere called Hansen's melting sphere is created, and the center coordinates of this sphere are created. Let be HSP of metal colloid.

The HSP of the substrate (thermoplastic resin) is obtained as follows. 0.4 g of small pieces cut out from the substrate (at least the portion including the region where the metal pattern is formed (the region containing the thermoplastic resin)) was put into 2 mL of each medium in Table 1 and charged at room temperature (25 ° C.) for 24 hours. put. Then, the change of the small piece after being left is visually observed, and if the small piece is melted or a crack is generated in the small piece, it is set to 1, and if there is no change in the small piece, it is set to 0. The HSP of each medium (that is, dD, dP and dH) is plotted three-dimensionally, and from the HSP distribution of the medium in which lysis or cracking of small pieces is seen, a sphere called Hansen's lysis sphere is created and the center of this sphere. Let the coordinates be the HSP of the substrate (thermoplastic resin).
The distance Dc (MPa ^0.5 ) is calculated from each HSP of the dispersion medium and the metal colloid thus obtained. Further, the distance Ds (MPa ^0.5 ) is calculated from each HSP of the dispersion medium and the substrate (thermoplastic resin).

The thermoplastic resin preferably contains at least one selected from the group consisting of polycarbonate resin, styrene resin, and polyester resin. Such a thermoplastic resin is suitable as a base material for forming a metal pattern because it is easy to mold and has high strength, but it dissolves in a dispersion medium such as that used for metal inks. easy. According to the above aspect of the present invention, even when the metal ink is applied to the region of the base material containing such a thermoplastic resin, it is possible to suppress the dissolution of the base material (specifically, the thermoplastic resin). it can.

From the viewpoint of further ensuring high stability of the metal colloid in the metal ink, the distance Dc is preferably 8.6 MPa ^0.5 or less. Further, from the viewpoint that the sinterability of the coating film can be improved and the increase in the resistance value of the metal pattern can be easily suppressed, the distance Dc is preferably 3 MPa ^0.5 or more.

The distance Ds is preferably 15 MPa ^0.5 or less. In this case, it is easy to secure high wettability of the metal ink on the substrate, and it is possible to prevent the metal ink from being repelled on the substrate.

The metal contained in the metal colloid is preferably at least one selected from the group consisting of silver, silver alloys, copper, and copper alloys. These metals have high conductivity and are suitable for forming metal patterns such as wiring patterns.

The metal colloid contains metal nanoparticles and a dispersant coordinated to the metal nanoparticles, and the average particle size of the metal nanoparticles is preferably 5 nm or more and 400 nm or less. When such a metal colloid is used, it becomes easy to secure high stability (specifically, dispersion stability) of the metal nanoparticles in the metal ink. Further, due to the nanosize effect of the metal nanoparticles, the metal is fused at a temperature lower than the melting point of the metal, so that the coating film of the metal ink formed on the base material can be fired at a relatively low temperature, and the obtained metal can be fired. It becomes easy to reduce the resistance of the pattern (metal film). Further, since it can be fired at a relatively low temperature, it is possible to suppress deterioration and deformation of the base material containing the thermoplastic resin due to heat.

The dispersant contained in the metal colloid preferably contains C _4-16 alkylamine. In this case, since the metal film can be formed even under mild conditions, deterioration and deformation of the base material containing the thermoplastic resin can be suppressed.

Hereinafter, the metal ink and its manufacturing method, and the manufacturing method of the substrate provided with the metal pattern will be described in more detail.

[Metal ink]
The metal ink contains a dispersion medium and a metal colloid dispersed in the dispersion medium. The metal colloid usually contains metal particles, and often contains metal particles and a dispersant coordinated to the metal particles. In addition to these components, the metal ink can contain a polymerization reactive compound, a polymerization initiator and the like. Further, the metal ink is preferably a firing type metal ink that forms a metal pattern by firing a coating film formed by coating on the surface of a base material.

(Metal particles)
As the metal material forming the metal particles, a simple substance of a metal, an alloy, or the like is used.
Examples of the metal element contained in the elemental metal or the alloy include a typical metal element and a transition metal element. Typical metal elements include, for example, Zn, Al, Ga, In, Ge, Sn, Pb, Sb, Bi and the like. Examples of the transition metal element include Ti, Zr, V, Cr, Mn, Fe, Ru, Co, Ni, Pd, Pt, Cu, Ag, Au and the like. The alloy preferably contains two or more of these metal elements. As the metal element, Al, Sn, Ti, Ni, Pt, Cu, Ag, Au and the like are preferable. As the metal material (metal contained in the metal colloid), Ag, Ag alloy, Cu, and Cu alloy are preferable, and Ag and Ag alloy are particularly preferable. These metals have high conductivity and are suitable for forming metal patterns such as wiring patterns.

The metal ink may contain a plurality of types of metal particles made of different materials. For example, the metal ink is formed of a first metal particle formed of Ag, Ag alloy, Cu, or Cu alloy, and a single metal other than Ag and Cu or an alloy other than Ag alloy and Cu alloy among the above-exemplified metals. It may be contained in combination with the generated second metal particles. In this case, the ratio of the first metal particles to the total metal particles is preferably 80% by mass or more, and may be 80% by mass or more and 99% by mass or less, or 85% by mass or more and 99% by mass or less.

The average particle size of the metal particles is, for example, 5 nm or more and 1500 nm or less.
The metal ink preferably contains metal nanoparticles as metal particles. Such metal inks are also called metal nano inks. When a metal colloid containing metal nanoparticles is used, the coating film of the metal ink formed on the substrate can be fired at a relatively low temperature due to the nano-size effect of the metal nanoparticles, so that the resistance of the obtained metal pattern can be obtained. It is possible to easily reduce the amount of ink, and it is also possible to suppress deterioration and deformation of the base material containing the thermoplastic resin due to heat. The average particle size of the metal nanoparticles can be selected from the range of 5 nm or more and less than 1000 nm. The average particle size of the metal nanoparticles is preferably 5 nm or more and 500 nm or less (or 5 nm or more and 400 nm or less), and more preferably 5 nm or more and 200 nm or less or 5 nm or more and 100 nm or less. By using metal nanoparticles having such an average particle size, it is possible to enhance the contact between the metal nanoparticles and to facilitate the fusion of the metal nanoparticles even at a relatively low temperature. Therefore, the metal nanoparticles are used. The conductivity of the metal pattern formed is likely to increase.

In the present specification, the average particle size is the particle size (D50) at a cumulative volume of 50% of the volume-based particle size distribution. The average particle size (D50) can be measured by a laser diffraction / scattering method using a laser diffraction type particle size distribution measuring device. Further, the average particle diameter of the metal particles is the same as the area surrounded by the outer edges of a plurality of (for example, 10) metal particles arbitrarily selected in the scanning electron microscope (SEM) photograph of the coating film of the metal ink. It may be calculated by finding the diameter of the circle (equivalent circle) having the above and averaging it.

The shape of the metal particles is not particularly limited, and may be any shape such as a spherical shape, an elliptical spherical shape, a polygonal columnar shape, a polygonal pyramid shape, a flat shape (flakes, scales, flakes, etc.), or similar shapes thereof. You may. From the viewpoint of easily enhancing the contact between the metal particles, a spherical shape, an elliptical spherical shape, a flat shape, or a shape similar to these is preferable.

As the metal particles, commercially available ones may be used, or those formed by evaporating a metal material may be used. Further, metal particles prepared by utilizing a chemical reaction in a liquid phase or a gas phase may be used.

(Dispersant)
By using the dispersant, the aggregation of metal particles in the metal ink is suppressed, and the metal colloid can be stabilized in the metal ink. The dispersant may be added at the time of preparing the metal ink and coordinated with the metal particles, but it is preferable to coordinate with the metal particles prior to the preparation of the metal ink. The dispersant may be coordinated with the metal particles by mixing with the metal particles and heating if necessary, or may be coordinated with the metal particles by using the dispersant in the process of producing the metal particles.

As the dispersant, for example, an organic compound having a polar functional group coordinating with the metal particles and an organic group having a low affinity for the metal particles (for example, a hydrophobic organic group) is used. Examples of polar functional groups include heteroatom-containing groups. Heteroatoms include, for example, nitrogen, sulfur, and / or oxygen atoms. Examples of the polar functional group include an amino group, a mercapto group, an oxygen-containing group (for example, a hydroxy group (including a phenolic hydroxy group), a carbonyl group, an ester group, a carboxy group, etc.) and the like. The dispersant may contain one kind of polar functional group, or may contain two or more kinds of polar functional groups.

Above all, from the viewpoint of room temperature stability, it is preferable to use an organic amine which is a compound containing an amino group. The organic amine may be any of a primary amine, a secondary amine, and a tertiary amine. The organic amine may be either a cyclic amine or a chain amine. Primary amines (among others, primary chain amines) are preferable in terms of easy coordination with metal particles. As the organic amine, for example, alkylamines (n-butylamine, pentylamine, hexylamine, octylamine, decylamine, dodecylamine, myristylamine, etc.) are preferable. C _4-16 alkylamines (eg, C _4-15 alkylamines) are preferred because of their high dispersion stability of the metal particles and their ease of removal during the metal pattern fabrication process, with C _6-14 alkylamines or C _{8- 12} Alkylating amines are even more preferred. When such an amine is used, a metal film can be formed even under mild conditions, so that deterioration and deformation of the base material containing the thermoplastic resin can be suppressed. Among them, amines having a small number of carbon atoms (for example, C _4-10 alkylamines, preferably C _6-10 alkylamines, and more preferably C _8-10 alkylamines) are highly reactive and are therefore mild to low temperature firing. It is more advantageous in forming a metal film under the conditions.

Since the dispersant is preferably removed at an appropriate stage in the process of forming the metal pattern, it is preferably a low molecular weight compound (for example, a compound having a molecular weight of 500 or less).

The amount of the dispersant (preferably the dispersant coordinated to the metal particles) contained in the metal ink is, for example, 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the metal particles, and is 0. It is preferably 3 parts by mass or more and 5 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less. When the amount of the dispersant is in such a range, the metal particles can be easily stabilized in the metal ink, and the dispersant can be easily removed.

(Dispersion medium)
As the dispersion medium, a medium in which the HSP distance Dc between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less and the HSP distance Ds between the dispersion medium and the base material (thermoplastic resin) is 10 MPa ^0.5 or more is used. used. As such a medium, a medium that is liquid at room temperature (25 ° C.) is used. As the dispersion medium, one kind of medium may be used alone, or two or more kinds of media may be used in combination. When two or more media are used, the media may be selected and / or the ratio of each medium may be adjusted so that the HSP distance of the mixture of the two or more media is within the above range. As the medium, an organic medium is preferable.

Distance Dc may be any 10 MPa ^0.5 or less (preferably 10.0 MPa ^0.5 or less). When the distance Dc exceeds 10 MPa ^0.5 , the stability of the metal colloid in the metal ink is greatly reduced. Distance Dc is preferably at 9 MPa ^0.5 or less, and more preferably 8.6 MPa ^0.5 or less. Distance Dc is, for example, 1 MPa ^0.5 or more, preferably 3 MPa ^0.5 or more, more preferably 4 MPa ^0.5 or more, may be 4.5 MPa ^0.5 or more or 4.6 MPa ^0.5 or more. These upper limit values and lower limit values can be arbitrarily combined. When the distance Dc is in such a range, it becomes easier to further secure high stability of the metal colloid in the metal ink. Distance Dc is, for example, 1 MPa ^0.5 or more (or 3 MPa ^0.5 or more) 10 MPa ^0.5 or less, 1 MPa ^0.5 or more (or 3 MPa ^0.5 or higher) 10.0 MPa ^0.5 or less, 1 MPa ^0.5 or more (or 3 MPa ^0.5 or more) 9 MPa ^0.5 or less, 1 MPa ^0.5 or more (or 3 MPa ^0.5 or higher) 8.6 MPa ^0.5 or less, 4 MPa ^0.5 or more (or 4.5 MPa ^0.5 or more) 10 MPa ^0.5 or less, 4 MPa ^0.5 or more (or 4.5 MPa ^0.5 or higher) 10.0 MPa ^0.5 or less, 4 MPa ^0.5 or more (or 4 .5MPa ^0.5 or higher) 9MPa ^0.5 or less, 4 MPa ^0.5 or more (or 4.5 MPa ^0.5 or higher) 8.6 MPa ^0.5 or less, 4.6 MPa ^0.5 or 10 MPa ^0.5 or less (or 10.0 MPa ^0.5 or less), or 4.6 MPa ^0.5 or more 9MPa ^It may be ^0.5 or less (or 8.6 MPa ^0.5 or less).

Distance Ds may be any 10 MPa ^0.5 or more (preferably 10.0 MPa ^0.5 or higher). If the distance Ds is less than 10 MPa ^0.5 , the region containing the thermoplastic resin of the base material will be dissolved. The distance Ds is, for example, 20 MPa ^0.5 or less, preferably 15 MPa ^0.5 or less, and more preferably 13 MPa ^0.5 or less. When the distance Ds is in such a range, it is easy to secure high wettability of the metal ink on the substrate, and it is possible to suppress the metal ink from being repelled on the substrate.

As the dispersion medium (specifically, the above-mentioned medium), for example, the distances Dc and Ds may satisfy the above-mentioned ranges, and the specific type is not particularly limited. Examples of the dispersion medium (specifically, the above medium) include alcohols, ethers, esters, ketones, hydrocarbons (alicyclic hydrocarbons, aromatic hydrocarbons, etc.) and the like.

The dD of HSP of the dispersion medium is, for example, 10 or more and 20 or less, preferably 13 or more and 19 or less, and further preferably 14 or more and 18 or less. The dP is, for example, 10 or less, preferably 1 or more and 9 or less, and more preferably 2.5 or more and 8 or less (for example, 2.5 or more and 7.5 or less). The dH is, for example, 20 or less, preferably 1 or more and 16 or less, and more preferably 3 or more and 15 or less. The HSP of the dispersion medium is not limited to such a range, but when each term is in such a range, it is easy to balance the distances Dc and Ds, and the high dispersion stability and the group of the metal particles are obtained. It is easy to obtain the effect of suppressing the dissolution of the material.

When the metal ink is applied onto the base material, it is preferable that a coating film having a desired shape can be formed, and the dispersion medium volatilizes quickly after the application. From such a viewpoint, the boiling point of the dispersion medium is preferably, for example, 130 ° C. or higher and 280 ° C. or lower, and 150 ° C. or higher and 250 ° C. or lower. When the dispersion medium contains a plurality of media, the boiling points of at least one medium are preferably within the above range, and the boiling points of all the media are more preferably within the above range.

The surface tension of the dispersion medium at 25 ° C. is preferably 20 mN / m or more and 40 mN / m or less, and more preferably 25 mN / m or more and 40 mN / m or less. In this case, the coatability of the metal ink can be improved. In addition, since the droplets are suppressed from spreading excessively, a fine metal pattern can be formed.
In this specification, the surface tension is determined by the suspension method using a contact angle meter.

The proportion of the dispersion medium in the metal ink is preferably 25% by mass or more and 95% by mass or less, and may be 25% by mass or more and 90% by mass or less. When the ratio of the dispersion medium is in such a range, constituent components such as metal particles contained in the metal ink can be easily dispersed in the dispersion medium, and good coatability can be easily ensured. Therefore, the metal ink is also suitable for jet coating (injection method, etc.).

(Polymerization reactive compound)
The polymerization-reactive compound may be selected according to the desired physical properties of the metal ink. A known polymerization-reactive compound can be used as long as it can be polymerized (including cross-linking and curing) by the action of the activated polymerization reaction initiator to form a polymer. Examples of the polymerization-reactive compound include a raw material for a polymer, for example, a monomer or a precursor such as an oligomer in which several monomers are connected, and a curable resin (photocurable resin, thermosetting resin, etc.) can also be used.

Examples of the curable resin include epoxy resin, acrylic resin, phenol resin, silicon resin, vinyl ester resin, vinyl ether resin, unsaturated polyester resin, diallyl phthalate resin, and urethane resin.
As the polymerizable compound, one type may be used alone, or two or more types may be used in combination.

(Polymer initiator)
The polymerization initiator may be selected according to the desired physical properties of the metal ink, the type of the polymerization reactive compound, and the like. As the polymerization initiator, one that is activated by the action of heat and / or light to promote the polymerization of the polymerization-reactive compound is used, and a known polymerization initiator can be used. As the polymerization initiator, for example, a radical polymerization initiator, an ionic polymerization initiator, or the like is used. Further, as the polymerization reaction initiator, other curing agents used in curable resins such as thermosetting resins and photocurable resins can also be used.
As the polymerization initiator, one type may be used alone, or two or more types may be used in combination.

(Other)
The metal ink may contain known additives, if desired. For example, the metal ink may contain a binder (resin binder, etc.), and when the metal ink contains a polymerization-reactive compound and a polymerization initiator, a curing accelerator and a reactive diluent are used depending on the type of the polymerization-reactive compound. , Surface conditioner and the like may be included.

The viscosity of the metal ink at 25 ° C. is preferably, for example, 1 mPa · s or more and 10000 mPa · s or less. When the metal ink is applied onto the base material by an inkjet method, it is preferable that the viscosity of the metal ink at 25 ° C. is 3 mPa · s or more and 300 mPa · s or less from the viewpoint of easily ensuring the ejection property at the nozzle.
In the present specification, the viscosity is the viscosity when measured at a rotation speed of 20 rpm using an E-type viscometer.

The metal ink is applied onto the substrate, and after 1 minute has passed at 25 ° C., the contact angle of the metal ink with respect to the substrate is preferably 5 ° or more and 30 ° or less, and 10 ° or more and 25 ° or less. Is more preferable. Since the metal ink has a high affinity for the region containing the thermoplastic resin of the base material, the metal ink may spread too much on the base material, but when the contact angle is in the above range, the metal ink Is suppressed from spreading too much. In addition, excessive repelling of the metal ink on the base material is also suppressed. Therefore, it becomes easy to form an elaborate metal pattern.

The contact angle can be measured from the lateral direction of the droplet using a contact angle meter (for example, DM-501 manufactured by Kyowa Interface Science Co., Ltd.). For example, the metal ink is applied onto the substrate, and the contact angle of the metal ink with respect to the substrate is measured after 1 minute has passed at 25 ° C. The contact angle can be measured by observing from the side using a contact angle meter.

The surface tension of the metal ink is preferably 25 mN / m or more and 40 mN / m or less, and more preferably 27 mN / m or more and 37 mN / m or less. When the surface tension is in such a range, the metal ink is prevented from spreading too much, and the metal ink is also suppressed from being excessively repelled, which is advantageous in obtaining an elaborate metal pattern.

Such a metal ink has high stability of the metal colloid in the metal ink, and can suppress the dissolution of the base material when applied on the region containing the thermoplastic resin of the base material. The base material may contain at least a thermoplastic resin in the region to which the metal ink is applied, and it is preferable that the region to which the metal ink of the base material is applied is formed of the thermoplastic resin.

The dD of HSP of the thermoplastic resin (specifically, the region portion containing the thermoplastic resin of the base material) is, for example, 15 or more and 25 or less, preferably 16 or more and 22 or less, and 17 or more and 19 or less. It is more preferable to have. The dP is, for example, 0 or more and 20 or less, preferably 0 or more and 15 or less, and more preferably 0 or more and 11 or less. The dH is, for example, 1 or more and 23 or less, preferably 1 or more and 15 or less, and further preferably 1 or more and 7 or less. These dD, dP, and dH ranges can be combined arbitrarily. The HSP of the thermoplastic resin (specifically, the region portion containing the thermoplastic resin of the base material) is not limited to such a range, but when each term is in such a range, the distance It is easy to adjust Ds, and it is easy to obtain the effect of suppressing the dissolution of the base material (thermoplastic resin).

Examples of the thermoplastic resin contained in the base material to which the metal ink is applied include polycarbonate resin, styrene resin (polystyrene (PS), acrylonitrile styrene copolymer (AS resin), and acrylonitrile butadiene styrene copolymer (ABS resin)). Etc.), olefin resin, vinyl resin, acrylic resin, polyacetal resin, polyamide resin, polyester resin (that is, thermoplastic polyester resin), halogen-containing resin, polyphenylene ether resin, polyphenylene sulfide resin and the like. Examples of the polyester resin include aromatic polyesters (polyalkylene arylate (polyethylene terephthalate, polybutylene terephthalate, etc.) and the like). The base material may contain one kind of these thermoplastic resins, or may contain two or more kinds of these thermoplastic resins. Of these, polycarbonate resin, styrene resin, and polyester resin are preferable. Since these thermoplastic resins are easy to mold and have high strength, they are suitable as a base material for forming a metal pattern, but they are easily dissolved in a dispersion medium such as that used for metal inks. .. In the present invention, even when the metal ink is applied to the region of the base material containing such a thermoplastic resin, the dissolution of the base material (thermoplastic resin) can be suppressed.

[Metal ink manufacturing method]
For the metal ink, a step of preparing a dispersion medium having an HSP distance Dc of 10 MPa ^0.5 or less and an HSP distance Ds of 10 MPa ^0.5 or more, and a step of preparing a metal ink in which a metal colloid is dispersed in the dispersion medium. It can be obtained by a manufacturing method comprising.

(Preparation process of dispersion medium)
In this step, a dispersion medium used for preparing the metal ink is prepared. Specifically, a dispersion medium having a distance Dc and a distance Ds within the above ranges is prepared according to the respective HSPs of the metal colloid and the thermoplastic resin contained in the region forming the metal pattern of the base material. For example, the distance Dc and the distance Ds are adjusted by selecting the type of dispersion medium and / or adjusting the mixing ratio of the plurality of dispersion media. Further, the dispersion medium once determined may be prepared so that the distance Dc and the distance Ds are within the above ranges, and the dispersion medium is mixed by mixing a plurality of dispersion media according to the mixing ratio of the once determined dispersion medium. May be prepared.

By including the preparation step of the dispersion medium in the production method, high stability of the metal colloid in the obtained metal ink can be ensured, and the basis for coating on the region containing the thermoplastic resin of the base material. It is possible to suppress the dissolution of the material (thermoplastic resin).

(Metal ink preparation process)
In this step, it is sufficient that a metal ink in which a metal colloid is dispersed in a dispersion medium can be prepared. For example, a metal ink can be prepared by mixing the constituent components of the metal ink (for example, metal particles and a dispersion medium). A known stirrer, mixer or the like is used to disperse the constituents more uniformly.

The mixing order of the components is not particularly limited. For example, some components may be mixed in advance, and the remaining components may be added and further mixed. Each component may be added at once or may be added in a plurality of times. The dispersant may be added when the metal particles and the dispersion medium are mixed, or may be coordinated with the metal particles and then mixed with the dispersion medium. The timing of adding other components (polymerization-reactive compound, polymerization initiator, and / or additive, etc.) is not particularly limited.

In a preferred embodiment, the step of preparing the metal ink includes a step of coordinating a dispersant with the metal particles to prepare a metal colloid and a step of dispersing the metal colloid in a dispersion medium to obtain a metal ink.

In the step of producing the metal colloid, for example, the dispersant can be coordinated with the metal particles by mixing the metal particles, the dispersant, and the liquid medium. If necessary, other components (additives (binder, etc.), etc.) may be added in this step.

As the liquid medium, a medium (solvent) that is liquid at room temperature (25 ° C.) at which the dispersant is dissolved is preferable. The liquid medium may be selected according to the type of dispersant. As the liquid medium, aliphatic alcohols, aliphatic esters and the like are preferable, but the liquid medium is not limited thereto. As the liquid medium, one type may be used alone, or two or more types may be used in combination. Mixing may be carried out under heating if necessary. The produced metal colloid is separated from the liquid medium by centrifugation or the like and recovered.

In the step of obtaining the metal ink, the metal colloid and the dispersion medium are mixed. If necessary, other components (polymerization-reactive compound, polymerization initiator, and / or additive, etc.) may be added in this step. In order to disperse the metal colloid more uniformly in the dispersion medium, a known stirrer, mixer or the like is used in this step.

[Manufacturing method of a base material having a metal pattern]
The method for producing a base material having a metal pattern includes a step of applying a metal ink on the base material to form a metal pattern. The metal pattern forming step can include a step of applying a metal ink to a base material to form a coating film and a step of firing the coating film to form a metal pattern (metal film). One aspect of the present invention also includes the use of the metal ink in the production method and the use of the metal ink for coating on a substrate to form a metal pattern.

As mentioned above, the substrate contains at least a thermoplastic resin in the area where the metal ink is applied. It is preferable that at least the region of the base material to which the metal ink is applied is formed of a thermoplastic resin. For example, the base material may include a layer containing a thermoplastic resin on the surface (or main surface) on the side to which the metal ink is applied and in the vicinity thereof, and the entire base material may contain the thermoplastic resin. .. The base material may have a layer containing a thermoplastic resin on the entire surface (or main surface) of the base material on the side to which the metal ink is applied, or may have a part thereof.

The material of the base material of the base material of the layer containing the thermoplastic resin is not particularly limited, and examples thereof include glass, silicon, and / or a cured resin.

(Metal pattern formation process)
(Coating film forming process)
In the coating film forming step, a metal ink is applied to the surface of the base material. The application of the metal ink is not particularly limited, and can be performed by a known application method (spin coating, spray coating, blade coating, screen printing, inkjet, etc.). Further, the coating film may be a pattern film such as wiring or hole filling, or may be a solid film.

The above-mentioned metal ink is suitable for non-contact jet coating (injection method, etc.) because the stability of the metal colloid in the metal ink is high. The coating by the inkjet method means non-contact jet coating. Non-contact jet coating is a coating method that uses air pressure, spring elasticity, vibration of a piezo element (piezoelectric element), etc. to blow metal ink onto an ink adherend, and is, for example, a mechanical type or a piezo type. The application is made using a non-contact jet dispenser. Non-contact jet coating is also suitable for forming a wiring pattern on the surface of a three-dimensional model or for producing a multilayer substrate. Here, the three-dimensional model refers to a material that is a base material of a circuit member having a three-dimensional structure.

(Drying process)
The base material having the coating film obtained in the coating film forming step may be dried, if necessary, prior to the firing step. The drying conditions can be appropriately determined according to the constituent components of the metal ink and the like. In the drying step, it is preferable to remove volatile components (dispersion medium, etc.).
The drying temperature is not particularly limited, and may be performed at a temperature at which volatile components can be removed. It is desirable that the drying temperature is lower than the firing temperature described later.

(Baking process)
In the firing step, the base material having the coating film obtained in the coating film forming step is fired. By firing, the metal particles contained in the coating film are fused to each other, and the resistance of the obtained metal film can be significantly reduced. In the case of metal nanoparticles, the nano-sized particles fuse at a temperature lower than the melting point of the metal, so that the effect of sufficiently reducing the resistance of the metal film can be obtained even at a relatively low temperature during firing. ..

The firing can be appropriately selected depending on the type of metal of the metal particles, and may be performed at, for example, 50 ° C. or higher and 250 ° C. or lower, 100 ° C. or higher and 250 ° C. or lower, or 150 ° C. or higher and 250 ° C. or lower. When an amine having a small number of carbon atoms is used as the dispersant, a metal film can be formed even under mild conditions. In this case, the firing temperature is preferably 150 ° C. or lower (for example, 50 ° C. or higher and 150 ° C. or lower), and may be 100 ° C. or higher and 150 ° C. or lower.

Firing may be carried out in the presence of a reducing agent, if necessary.
The firing may be carried out in an atmosphere of an inert gas or in the atmosphere.
The firing time is not particularly limited, but may be, for example, 5 minutes or more and 120 minutes or less.

When a polymerization reaction initiator that is activated by the action of heat is used, it may be activated by the heat applied in the drying step and / or the firing step to proceed with the polymerization of the polymerization-reactive compound. When a polymerization reaction initiator that is activated by the action of light is used, it is preferable to irradiate the coating film with light at an appropriate stage from the formation of the coating film to the firing step. The drying step and / or the firing step may be performed under light irradiation.

[Example]
Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<< Examples 1 to 10 and Comparative Examples 1 to 5 >>
(1) Preparation of metal colloid 20 g of silver nitrate, 100 g of isobutanol, and 100 g of dodecylamine (dispersant) were mixed. The resulting mixture was heated to a temperature of 100 ° C. and refluxed for 5 hours. The solid content in the obtained mixture was settled by centrifugation and recovered. The recovered solid content was washed with methanol three times and then centrifuged to recover silver nanoparticles coordinated with dodecylamine. The mass ratio of the silver nanoparticles to the dodecylamine coordinated to the silver nanoparticles was 100: 0.5.

A dispersion paste was prepared by dispersing the recovered silver nanoparticles in diethylene glycol monobutyl ether using three rolls. The obtained dispersed paste was applied to a substrate by spin coating, and SEM photographs of silver nanoparticles were taken. When the average particle size of the silver nanoparticles was calculated by the method described above in this photographed image, it was about 40 nm.

(2) Preparation of metal ink The metal colloid containing the silver nanoparticles recovered in (1) above was dispersed in the dispersion medium shown in Table 2 using a homogenizer, and then using a disc filter having a mesh size of 1 μm. It was filtered to prepare a metal ink. The concentration of the metal colloid in the metal ink was 40% by mass.

(3) Evaluation The following evaluation was performed.
(A) Measurement of HSP and calculation of distances Dc and Ds Using metal inks, the HSPs of the dispersion medium and the metal colloid were determined by the procedure described above. The HSP of the dispersion medium is shown in Table 2. The HSP of the metal colloid had a dD of 19.5, a dP of 4.1 and a dH of 8.8.
Further, it is formed of a plate-shaped substrate (substrate A) formed of a polycarbonate resin (Teijin Corporation, Panlite L-1225Y) and an acrylonitrile styrene-butadiene resin (UMG ABS EX18A 11001, manufactured by UMG ABS Co., Ltd.). The HSPs of each of the plate-shaped substrates (substrate B) were obtained by the procedure described above. In each of the substrates, the dD was 18.4, the dP was 10.1, and the dH was 2.4. As the HSP calculation software, HSPiP 4th Edition 4.1.07 was used.
Distances Dc and Ds were calculated from these HSPs.

(B) Dispersion Stability The metal ink was stored at 25 ° C. for 1 month, and then the presence or absence of precipitation was visually observed and evaluated according to the following criteria.
A: No precipitation is confirmed.
B: Precipitation is confirmed.

(C) Volume resistivity A metal ink was applied to each of the substrate A and the substrate B using a bar coater, and a metal pattern was formed by heating and firing at 120 ° C. for 30 minutes with a blower dryer. The volume resistivity (μΩ · cm) of the formed metal pattern was measured by a four-terminal method using a resistivity meter (Loresta manufactured by Mitsubishi Chemical Analytech Co., Ltd.).
The evaluation results of (a) to (c) are shown in Table 2.

As shown in Table 2, in the examples in which the distance Dc of HSP was 10 MPa ^0.5 or less and the distance Ds was 10 MPa ^0.5 or more, high dispersion stability of the metal colloid could be ensured. In addition, the volume resistivity was also lowered. It is considered that this is because the dissolution of the substrate by the metal ink was suppressed.

On the other hand, in Comparative Examples 1 and 2 in which the distance Dc of HSP exceeds 10 MPa ^0.5 , precipitation was confirmed in the metal ink after storage, and the dispersion stability of the metal colloid was lowered. Further, in Comparative Examples 3 to 5 in which the distance Ds was less than 10 MPa ^0.5 , the volume resistivity was extremely large. It is considered that this is because the dissolution of the substrate became remarkable.

In the above example, an example using a base material containing a polycarbonate resin and a styrene resin was shown, but if the Dc and Ds of HSP are 10 MPa ^0.5 or less, a polyester resin (for example, a polybutylene terephthalate resin (for example, for example) It was also confirmed that the same or similar effects as those in the above examples can be obtained when a base material containing another thermoplastic resin such as Dulanex 2002)) manufactured by Wintech Polymer Co., Ltd. is used.

Although the present invention has described preferred embodiments at this time, such disclosures should not be construed in a limited way. Various modifications and modifications will undoubtedly become apparent to those skilled in the art belonging to the present invention by reading the above disclosure. Therefore, the appended claims should be construed to include all modifications and modifications without departing from the true spirit and scope of the invention.

According to the metal ink according to the embodiment of the present invention, the dispersion stability of the metal colloid is high, and the dissolution of the thermoplastic resin can be suppressed. Therefore, it is suitable for forming a metal pattern such as a wiring pattern on a base material having a region containing a thermoplastic resin. It can also be used for forming a wiring pattern on the surface of a three-dimensional modeled object, manufacturing a multilayer substrate, and the like.

Claims (15)

A metal ink that is applied onto a substrate to form a metal pattern.
Contains metal colloids and dispersion media
The base material contains a thermoplastic resin at least in a region forming the metal pattern.
The distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less.
A metal ink in which the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. The metal ink according to claim 1, wherein the thermoplastic resin contains at least one selected from the group consisting of a polycarbonate resin, a styrene resin, and a polyester resin. The metal ink according to claim 1 or 2, wherein the distance Dc is 8.6 MPa ^0.5 or less. The metal ink according to any one of claims 1 to 3, wherein the distance Dc is 3 MPa ^0.5 or more. The metal ink according to any one of claims 1 to 4, wherein the distance Ds is 15 MPa ^0.5 or less. The dispersion term dD of the Hansen solubility parameter of the dispersion medium is 10 or more and 20 or less, the polar term dP is 10 or less, and the hydrogen bond term dH is 20 or less, any one of claims 1 to 5. The metal ink described in the section. The dispersion term dD of the Hansen solubility parameter of the thermoplastic resin is 15 or more and 25 or less, the polar term dP is 0 or more and 20 or less, and the hydrogen bond term dH is 1 or more and 23 or less. The metal ink according to any one of 6. The metal ink according to any one of claims 1 to 7, wherein the metal contained in the metal colloid is at least one selected from the group consisting of silver, a silver alloy, copper, and a copper alloy. The metal colloid contains metal nanoparticles and a dispersant coordinated to the metal nanoparticles.
The metal ink according to any one of claims 1 to 8, wherein the average particle size of the metal nanoparticles is 5 nm or more and 400 nm or less. The metal ink according to claim 9, wherein the dispersant contains a C _4-16 alkylamine. The metal ink according to any one of claims 1 to 10, wherein the ratio of the dispersion medium in the metal ink is 25% by mass or more and 95% by mass or less. A method for producing a metal ink that contains a metal colloid and a dispersion medium and is applied onto a substrate to form a metal pattern.
The base material contains a thermoplastic resin at least in a region forming the metal pattern.
Prepare the dispersion medium in which the distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less, and the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. And the process to do
A method for producing a metal ink, comprising a step of preparing a metal ink in which the metal colloid is dispersed in the dispersion medium. The method for producing a metal ink according to claim 12, wherein the thermoplastic resin contains at least one selected from the group consisting of a polycarbonate resin, a styrene resin, and a polyester resin. A process of applying metal ink to form a metal pattern on a base material is provided.
The base material contains a thermoplastic resin at least in a region forming the metal pattern.
The metal ink contains a metal colloid and a dispersion medium.
The distance Dc of the Hansen solubility parameter between the dispersion medium and the metal colloid is 10 MPa ^0.5 or less.
A method for producing a base material having a metal pattern, wherein the distance Ds of the Hansen solubility parameter between the dispersion medium and the thermoplastic resin is 10 MPa ^0.5 or more. The method for producing a base material having a metal pattern according to claim 14, wherein the thermoplastic resin contains at least one selected from the group consisting of a polycarbonate resin, a styrene resin, and a polyester resin.