TW201932551A - Metal ink, method for producing metal ink, and method for producing substrate with metal pattern - Google Patents

Abstract

A metal ink according to the present invention, which is applied to a substrate for the purpose of forming a metal pattern, contains a metal colloid and a dispersion medium. With respect to the substrate, at least a region where the metal pattern is to be formed contains a thermoplastic resin. The distance Dc between the Hansen solubility parameter of the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa0.5 or less; and the distance Ds between the Hansen solubility parameter of the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa0.5 or more.

Description

Metal ink, method for producing metal ink, and method for manufacturing substrate with metal pattern

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

BACKGROUND ART When forming a metal pattern such as a wiring pattern or a conductive layer of an electrode, a metal ink containing metal nanoparticles is used. The metallic ink is applied to the surface of the substrate when the metal pattern is formed. A resin film or the like is formed on the surface of the substrate (for example, Patent Document 1).

Advance Technical Document Patent Document Patent Document 1: Japanese Patent Laid-Open Publication No. 2013-221058

SUMMARY OF THE INVENTION Problems to be Solved by the Invention As long as a metal pattern can be directly formed on a substrate formed of various thermoplastic resins, the step of coating the surface of the substrate with a resin film can be omitted, which is simple. However, most thermoplastic resins have low solvent resistance and are easily dissolved by a dispersion medium contained in the metallic ink. If the substrate is dissolved by the metallic ink, the electric resistance becomes large, the precision of the metal pattern is lowered, or the product is defective. On the other hand, if a dispersion medium which does not dissolve the thermoplastic resin is used, the stability of the metal colloid in the metallic ink is lowered.

Means for Solving the Problem One aspect of the present invention relates to a metal ink for coating a substrate to form a metal pattern.
Contains metal colloids and dispersion media,
A region in which at least the aforementioned metal pattern is formed in the substrate includes a thermoplastic resin.
The distance Dc between the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa ^0.5 or less.
The distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa ^0.5 or more.

Another aspect of the present invention relates to a method of manufacturing a metallic ink comprising a metal colloid and a dispersion medium and used for coating a substrate to form a metal pattern.
a region of the foregoing substrate in which at least the aforementioned metal pattern is formed comprises a thermoplastic resin;
The method for manufacturing the aforementioned metal ink comprises the following steps:
a step of preparing the dispersion medium, wherein the distance Dc between the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa ^0.5 or more; A step of a metallic ink obtained by dispersing the metal colloid in the dispersion medium.

Another aspect of the present invention relates to a method for producing a substrate having a metal pattern, comprising the steps of coating a metal ink on a substrate to form a metal pattern,
A region in which at least the aforementioned metal pattern is formed in the substrate includes a thermoplastic resin.
The foregoing metal ink comprises a metal colloid and a dispersion medium,
The distance Dc between the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa ^0.5 or less.
The distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa ^0.5 or more.

The effect of the invention can ensure high stability of the metal colloid in the metallic ink, and when the metal pattern is formed on the region containing the thermoplastic resin of the substrate, the dissolution of the substrate can be suppressed.

The novel features of the invention are set forth in the appended claims.

In order to carry out the invention, it is necessary to ensure the stability (specifically, dispersion stability) of the metal colloid in the metallic ink for the metallic ink used to form the metal pattern. On the other hand, in the field of electronics, in recent years, a technique of forming a wiring pattern using a metal ink on a substrate formed of a thermoplastic resin has been studied. However, a dispersion medium which easily ensures the stability of the metal colloid is easily dissolved in the thermoplastic resin. Further, in the case of the metallic ink, it is also necessary to adjust the affinity of the substrate to the metallic ink, the volatility of the dispersion medium contained in the metallic ink, and the like in a balanced manner.

A metallic ink according to an aspect of the present invention is a metallic ink comprising a metal colloid and a dispersion medium and coated on a substrate to form a metal pattern. A region in which at least a metal pattern is formed in the substrate contains a thermoplastic resin. The distance Dc between the dispersion medium and the Hansen solubility parameter (HSP) of the metal colloid is 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the HSP of the thermoplastic resin is 10 MPa ^0.5 or more. Further, the solubility parameter is a measure of the affinity between the substances, and the HSP is represented by a three-dimensional vector of the dispersion term dD, the polar term dP, and the hydrogen bond term dH. Further, another aspect of the present invention also includes the use of the above-described metallic ink for forming a metal pattern on a substrate.

Such a metallic ink can be produced by a manufacturing method comprising the steps of preparing a dispersion medium having a distance Dc of 10 MPa ^0.5 or less from the HSP of the metal colloid, and a distance Ds between the dispersion medium and the HSP of the thermoplastic resin. 10MPa ^0.5 or more; and a step of preparing a metal ink which is obtained by dispersing a metal colloid in a dispersion medium. Still other aspects of the invention also include a method of producing the above metal ink.

Another aspect of the present invention also includes a method of producing a substrate having a metal pattern, comprising the step of coating a metal ink on a substrate to form a metal pattern. Here, a region in which at least a metal pattern is formed in the substrate contains a thermoplastic resin. The metallic ink contains a metal colloid and a dispersion medium. The distance Dc between the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa ^0.5 or more. Furthermore, in still another aspect of the present invention, the use of the metal ink in the method for producing a substrate having a metal pattern is also included.

According to the above aspect of the invention, the distance Dc between the dispersion medium and the HSP of the metal colloid is adjusted to 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the HSP of the substrate (specifically, the thermoplastic resin) is adjusted to 10 MPa ^0.5 or more. Thereby, high stability of the metal colloid in the metallic ink can be ensured, and dissolution of the substrate when the metallic ink is applied to the region containing the thermoplastic resin of the substrate can be suppressed. By suppressing the dissolution of the substrate (specifically, the thermoplastic resin) by the metallic ink, the increase in resistance of the metal pattern can be suppressed. Further, since the metal colloid has high stability in the metallic ink, the metallic ink can be stably stored for a long period of time. Further, the metal colloid usually contains metal particles and a dispersing agent coordinated to the metal particles. In the above aspect of the invention, the distance Dc is calculated based on the HSP of the metal colloid. Therefore, compared with the case where the HSP of the organic group (hydrophobic group or the like) having a low affinity for the metal particles by the dispersing agent or the dispersing agent is separated from the HSP of the dispersion medium, the metal colloid can be selected with high precision. Dispersing the medium ensures high stability of the metal colloid in the metallic ink.

Further, the distances Dc and Ds can be obtained as follows.
First, the precipitate which settled after centrifuging the metallic ink and the supernatant were separately recovered. The type and composition of the dispersion medium contained in the supernatant were determined by gas chromatography analysis (mixing ratio in the case of a mixture). Then, using the HSP calculation software HSPiP (available from the official website of HSP and HSPiP), the dispersion term dD, the polar term dP, and the hydrogen bond term dH of the HSP of the dispersion medium are determined from the type and composition.

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

[Table 1]

The HSP of the metal colloid is specifically determined as follows. The sediment was added to each medium of Table 1 at a concentration of 0.1% by mass, and stirred at room temperature (25 ° C) for 10 minutes by a roll type vibrator. After stirring, it was allowed to stand at room temperature (25 ° C) for 1 hour, and if the metal colloid dispersion was set to 1, the metal colloid precipitate was set to 0. The HSP (i.e., dD, dP, and dH) of each medium is three-dimensionally drawn, and a HSP distribution of a medium in which the metal colloid is dispersed is formed into a ball called Hansen's dissolution ball, and the center coordinates of the ball are set as HSP of the metal colloid.

The HSP of the substrate (thermoplastic resin) was determined as follows. 0.4 g of a small piece cut out from a substrate (including a region in which at least a metal pattern was formed (a region containing a thermoplastic resin)) was placed in 2 mL of each medium of Table 1, and left at room temperature (25 ° C) for 24 hours. Then, the change of the small piece after the placement was visually observed, and if the small piece was dissolved or the crack occurred in the small piece was set to 1, it was set to 0 if the small piece did not change. The HSP (ie dD, dP and dH) of each medium is three-dimensionally drawn, and the HSP distribution of the medium in which the small pieces are dissolved or cracked is formed into a ball called Hansen's dissolution ball, and the center coordinates of the ball are set as the substrate (thermoplastic). Resin) HSP.
The distance Dc (MPa ^0.5 ) was calculated from the HSP of each of the dispersion medium and the metal colloid thus obtained. Further, the distance Ds (MPa ^0.5 ) was calculated from the HSP of each of the dispersion medium and the substrate (thermoplastic resin).

The thermoplastic resin preferably contains at least one selected from the group consisting of polycarbonate resins, styrene resins, and polyester resins. Since such a thermoplastic resin is easy to be formed and has high strength, it is suitable as a base material for forming a metal pattern, but is easily dissolved in, for example, a dispersion medium used for a metallic ink. According to the above aspect of the invention, even when the metal ink is applied to the region of the base material containing the thermoplastic resin, the dissolution of the substrate (specifically, the thermoplastic resin) can be suppressed.

From the viewpoint of further ensuring high stability of the metal colloid in the metallic ink, the distance Dc is preferably 8.6 MPa ^0.5 or less. Moreover, the distance Dc is preferably 3 MPa ^0.5 or more from the viewpoint of improving the sinterability of the coating film and suppressing an increase in the resistance value of the metal pattern.

Distance Ds is suitably 15MPa ^0.5 or less. At this time, it is easy to ensure high wettability of the metal ink to the substrate, and it is possible to suppress the metallic ink from being repelled on the substrate.

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

The metal colloid includes metal nanoparticles and a dispersant coordinated to the metal nanoparticles, and the average particle diameter of the metal nanoparticles is preferably 5 nm or more and 400 nm or less. When such a metal colloid is used, it is easy to ensure high stability (specifically, dispersion stability) of the metal nanoparticles in the metallic ink. Moreover, since the nano-size effect of the metal nano-particles is melted at a temperature lower than the melting point of the metal, the metal ink coating film formed on the substrate can be fired at a lower temperature, and the obtained metal is easily reduced. The resistance of the pattern (metal film). Further, since the firing can be performed at a relatively low temperature, deterioration or deformation due to heat due to heat of the substrate containing the thermoplastic resin can be suppressed.

The dispersant contained in the metal colloid preferably contains a C _4-16 alkylamine. At this time, since the metal film can be formed under mild conditions, deterioration or deformation of the substrate containing the thermoplastic resin can be suppressed.

Hereinafter, the metal ink, the method for producing the same, and the method of manufacturing the substrate having 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. Metal colloids usually contain metal particles, and most of them contain metal particles and a dispersant coordinated to the metal particles. The metal ink may contain a polymerization reactive compound, a polymerization initiator, or the like in addition to these components. Further, the metal ink is preferably a fired metal ink in which a metal pattern is formed by firing a coating film formed on the surface of the substrate.

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

The metal ink may also comprise a plurality of metal particles of different materials. For example, the metal ink may be combined with a first metal particle formed of Ag, an Ag alloy, Cu, or a Cu alloy, and a second metal formed of an alloy other than Ag and Cu, or an alloy of Ag and Cu, and an alloy other than the Cu alloy. Contained by particles. In this case, the ratio of the first metal particles to the entire 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 diameter 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 metallic inks are also known as metallic nano inks. When a metal colloid containing metal nanoparticles is used, since the metal ink coating film formed on the substrate can be baked at a lower temperature by the nano-size effect of the metal nanoparticles, it is easy to reduce the resistance of the obtained metal pattern. Further, deterioration or deformation due to heat of the substrate containing the thermoplastic resin can also be suppressed. The average particle diameter of the metal nanoparticles can be selected from the range of 5 nm or more and less than 1000 nm. The average particle diameter 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), preferably 5 nm or more and 200 nm or less, or 5 nm or more and 100 nm or less. By using the metal nanoparticles having such an average particle diameter, the contact between the metal nanoparticles can be improved, and the metal nanoparticles can be easily fused at a lower temperature, so that the metal pattern formed by using the metal nano ink is electrically conductive. Sex is easy to improve.

Incidentally, the average particle diameter in the present specification means a particle diameter (D50) of 50% of the cumulative volume of the particle size distribution based on the volume. The average particle diameter (D50) was measured by a laser diffraction particle size distribution measuring apparatus by a laser diffraction scattering method. Further, the average particle diameter of the metal particles may be obtained by scanning electron microscopy (SEM) photographs of the metallic ink coating film by enclosing the outer edges of a plurality of (for example, ten) metal particles which are arbitrarily selected. The diameter of a circle (equivalent circle) having the same area is calculated and averaged.

The shape of the metal particles is not particularly limited, and may be any of a spherical shape, an elliptical shape, a polygonal column shape, a polygonal pyramid shape, a flat shape (flaky shape, a scale shape, a small piece shape, or the like), or the like. shape. From the viewpoint of easily increasing the contact between the metal particles, a spherical shape, an elliptical shape, a flat shape, or the like is preferable.

As the metal particles, those commercially available can be used, and those formed by evaporating a metal material can also be used. Further, metal particles produced by a chemical reaction in a liquid phase or a gas phase may also be used.

(Dispersant)
By using a dispersing agent, aggregation of metal particles in the metallic ink can be suppressed, and the metal colloid can be stabilized in the metallic ink. The dispersant may be added to coordinate with the metal particles when the metal ink is prepared, but may also be coordinated to the metal particles before the metal ink is prepared. The dispersing agent may be mixed with the metal particles and heated as needed, thereby coordinating with the metal particles, or by coordinating with the metal particles by using a dispersing agent in the production of the metal particles.

As the dispersant, for example, an organic compound having an organic group having a lower affinity for a metal particle and a lower affinity for a metal particle (for example, a hydrophobic organic group) is used. Examples of the functional group of the polar group include a group containing a hetero atom. Examples of the hetero atom include a nitrogen atom, a sulfur atom, and/or an oxygen atom. Examples of the functional group of the polar group include an amine group, a mercapto group, and an oxygen-containing group (for example, a hydroxyl group (including a phenolic hydroxyl group), a carbonyl group, an ester group, a carboxyl group, etc.). The dispersing agent may contain one functional group of one polarity, and may also contain two or more types.

Among them, from the viewpoint of room temperature stability, an organic amine which is a compound containing an amine group is preferably used. The organic amine can be any of a primary amine, a secondary amine, and a tertiary amine. The organic amine may also be any of a cyclic amine and a chain amine. From the standpoint of easy coordination with metal particles, it is preferably a primary amine (especially a primary chain amine). As the organic amine, for example, an alkylamine (n-butylamine, pentylamine, hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, etc.) is preferable. From the viewpoint of high dispersion stability of the metal particles and easy removal during the production of the metal pattern, a C _4-16 alkylamine (for example, a C _4-15 alkylamine), more preferably a C _{6-14 is} preferable. Alkylamine or C _8-12 alkylamine. When such an amine is used, since a metal film can be formed under mild conditions, deterioration or deformation of the substrate containing the thermoplastic resin can be suppressed. Among them, an amine having a small carbon number (for example, a C _4-10 alkylamine, preferably a C _6-10 alkylamine, more preferably a C _8-10 alkylamine) is low in reactivity due to its high reactivity. It is more advantageous to form a metal film under firing conditions.

The dispersant is preferably a low molecular compound (e.g., a compound having a molecular weight of 500 or less) because it is preferably removed at an appropriate stage of the metal pattern forming process.

The amount of the dispersant (preferably a dispersant which is preferably coordinated to the metal particles) contained in the metallic ink is, for example, 0.1 parts by mass or more and 10 parts by mass or less, preferably 0.3 parts by mass or more and 5 parts by mass based on 100 parts by mass of the metal particles. It is preferably 0.5 parts by mass or more and 5 parts by mass or less by mass or less. When the dispersing amount is in the above range, the metal particles are easily stabilized in the metallic ink, and the dispersing agent is easily removed.

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

Distance Dc can 10MPa ^0.5 or less (preferably 10.0MPa ^0.5 or less). If the distance Dc exceeds 10 MPa ^0.5 , the stability of the metal colloid in the metallic ink is greatly reduced. The distance Dc is preferably 9 MPa ^0.5 or less, preferably 8.6 MPa ^0.5 or less. For example, the above distance Dc 1MPa ^0.5, preferably 3MPa ^0.5 or more, more preferably 4MPa ^0.5 or more, and still more preferably 4.5MPa ^0.5 or more than 4.6MPa ^0.5. These upper limit values and lower limit values can be arbitrarily combined. When the distance Dc is in the above range, it is possible to further ensure high stability of the metal colloid in the metallic ink. Distance Dc or more, for example, may also be 1MPa ^0.5 (3MPa ^0.5 or more) and 10MPa ^0.5 or less, more 1MPa ^0.5 (3MPa ^0.5 or more) 10.0MPa ^0.5 and less than 1MPa ^0.5 (3MPa ^0.5 or more) and 9MPa ^0.5 or less, 1MPa ^0.5 or more ^(0.5 or more 3MPa) ^0.5 and 8.6 MPa or less, 4MPa ^0.5 or more ^(0.5 or more 4.5MPa) ^0.5 and 10 MPa or less, 4MPa ^0.5 or more ^(0.5 or more 4.5MPa) and 10.0MPa ^0.5 or less, 4MPa ^0.5 above (or 4.5MPa ^0.5 above) and 9MPa ^0.5 or less, 4MPa ^0.5 above (4.5MPa ^0.5 or more) and 8.6MPa ^0.5 or less, more 4.6MPa ^0.5 or less and 10MPa ^0.5 (10.0MPa ^0.5 or less), or more and 4.6MPa ^0.5 9MPa ^0.5 The following (or 8.6MPa ^0.5 or less).

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

The dispersion medium (specifically, the above medium) may be, for example, the distances Dc and Ds may satisfy the above range, 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.).

The dD of the HSP of the dispersion medium is, for example, 10 or more and 20 or less, preferably 13 or more and 19 or less, and more preferably 14 or more and 18 or less. dP is, for example, 10 or less, preferably 1 or more and 9 or less, more preferably 2.5 or more and 8 or less (for example, 2.5 or more and 7.5 or less). dH is, for example, 20 or less, preferably 1 or more and 16 or less, more preferably 3 or more and 15 or less. The HSP of the dispersion medium is not limited to the above range, but when it is in the above range, the balance between the distances Dc and Ds is easily obtained, and the high dispersion stability of the metal particles or the dissolution suppressing effect of the substrate can be easily obtained.

It is preferred to form a coating film of a desired shape when the metal ink is coated on the substrate, and the dispersion medium is rapidly volatilized after coating. From this point of view, the boiling point of the dispersion medium is, for example, 130 ° C or more and 280 ° C or less, preferably 150 ° C or more and 250 ° C or less. Furthermore, when the dispersion medium comprises a plurality of media, it is preferred that the boiling point of at least one of the media falls within the above range, and preferably the boiling point of all the media falls within the above range.

The surface tension at 25 ° C of the dispersion medium is preferably 20 mN/m or more and 40 mN/m or less, preferably 25 mN/m or more and 40 mN/m or less. At this time, the metallic ink coating property can be improved. Further, since the droplets can be prevented from excessively expanding, a fine metal pattern can be formed.
Further, in the present specification, the surface tension is obtained by a hanging drop method using a contact angle meter.

The ratio of the dispersion medium to the metallic 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 the above range, constituent components such as metal particles contained in the metallic ink are easily dispersed in the dispersion medium, and it is easy to ensure good coatability. Therefore, the metallic ink is also suitable for spraying (inkjet method, etc.).

(polymerizable reactive compound)
The polymerizable compound can be selected depending on the desired physical properties of the metal ink. As long as the polymer can be formed by polymerization (including crosslinking or hardening) by the action of the activated polymerization initiator, a known polymerizable compound can be used. Examples of the polymerization-reactive compound include a polymer raw material, for example, a precursor such as a monomer or an oligomer obtained by connecting a plurality of monomers, and a curable resin (photocurable resin, thermosetting resin, or the like) may be used.

Examples of the curable resin include an epoxy resin, an acrylic resin, a phenol resin, an anthracene resin, a vinyl ester resin, a vinyl ether resin, an unsaturated polyester resin, a diallyl phthalate resin, and a polyurethane resin.
The polymerizable compounds may be used alone or in combination of two or more.

(polymerization initiator)
The polymerization initiator can be selected depending on the desired physical properties of the metallic ink or the kind of the polymerization-reactive compound. The polymerization initiator is activated by the action of heat and/or light to carry out polymerization of the polymerization-reactive compound, 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 initiator, other curing agents used for the curable resin such as a thermosetting resin or a photocurable resin can be used.
The polymerization initiator may be used alone or in combination of two or more.

(other)
The metal ink may also contain well-known additives as needed. 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, it may contain a hardening accelerator, a reactive diluent, and a surface conditioner depending on the kind of the polymerization reactive compound. Wait.

The viscosity at 25 ° C of the metallic ink is, for example, preferably 1 mPa·s or more and 10000 mPa·s or less. When the metallic ink is applied to the substrate by an inkjet method from the viewpoint of easily ensuring the discharge property of the nozzle, the viscosity of the metallic ink at 25 ° C is preferably 3 mPa·s or more and 300 mPa·s or less.
In the present specification, the viscosity is measured using an E-type viscometer at a rotational speed of 20 rpm.

After the metal ink is applied to the substrate at 25 ° C for 1 minute, the contact angle of the metal ink with respect to the substrate is preferably 5° or more and 30° or less, preferably 10° or more and 25° or less. Since the metallic ink has a high affinity for the region containing the thermoplastic resin of the substrate, the metallic ink is excessively spread on the substrate. However, when the contact angle is in the above range, excessive expansion of the metallic ink can be suppressed. Further, it is also possible to suppress excessive repulsion of the metallic ink on the substrate. Therefore, it is easy to form a delicate metal pattern.

The contact angle can be measured from the lateral direction of the droplet using a contact angle meter (e.g., Resin Interface Science, DM-501). For example, the contact angle of the metallic ink with respect to the substrate after applying the metallic ink to the substrate and passing at 25 ° C for 1 minute is measured. The contact angle can be measured from a lateral view using a contact angle meter.

The surface tension of the metallic ink is preferably 25 mN/m or more and 40 mN/m or less, preferably 27 mN/m or more and 37 mN/m or less. When the surface tension is in the above range, excessive expansion of the metallic ink can be suppressed, and the metallic ink can be suppressed from being excessively repelled, so that it is advantageous to obtain a fine metal pattern.

Such a metallic ink has high stability in the metallic ink, and can suppress dissolution of the substrate when it is applied to the region of the substrate containing the thermoplastic resin. The substrate may comprise at least a thermoplastic resin in the region where the metallic ink is applied, and preferably the region of the coated metal ink of the substrate is formed of a thermoplastic resin.

The dD of the HSP of the thermoplastic resin (specifically, the portion of the substrate including the thermoplastic resin) is, for example, 15 or more and 25 or less, preferably 16 or more and 22 or less, more preferably 17 or more and 19 or less. dP is, for example, 0 or more and 20 or less, preferably 0 or more and 15 or less, more preferably 0 or more and 11 or less. dH is, for example, 1 or more and 23 or less, preferably 1 or more and 15 or less, more preferably 1 or more and 7 or less. The ranges of these dD, dP and dH can be arbitrarily combined. The HSP of the thermoplastic resin (specifically, the portion of the substrate containing the thermoplastic resin) is not limited to the above range, but when it is in the above range, the distance Ds is easily adjusted, and the dissolution inhibiting effect of the substrate (thermoplastic resin) is easily obtained. .

Examples of the thermoplastic resin contained in the substrate coated with the metallic ink include polycarbonate resin, styrene resin (polystyrene (PS), acrylonitrile styrene copolymer (AS resin), acrylonitrile butadiene benzene. Ethylene copolymer (ABS resin), etc., olefin resin, vinyl resin, acrylic resin, polyacetal resin, polyamide resin, polyester resin (ie thermoplastic polyester resin), halogen-containing resin, polyphenylene ether resin, poly Stretching benzene sulfur resin, etc. Examples of the polyester resin include aromatic polyesters (polyalkylene aryl esters (polyethylene terephthalate, polybutylene terephthalate, etc.)) and the like. The base material may contain one type of these thermoplastic resins, or may contain two or more types. Among them, preferred are polycarbonate resins, styrene resins, and polyester resins. Since these thermoplastic resins are easy to be formed and have high strength, they are suitable as a base material for forming a metal pattern, but are easily dissolved in, for example, a dispersion medium used for a metallic ink. In the present invention, even when a metal ink is applied to a region of the substrate containing the thermoplastic resin, dissolution of the substrate (thermoplastic resin) can be suppressed.

[Method of manufacturing metal ink]
The metal ink can be obtained by a manufacturing method comprising the steps of preparing a dispersion medium, the distance Dc of the dispersion medium HSP is 10 MPa ^0.5 or less, and the distance Ds of the HSP is 10 MPa ^0.5 or more; and the step of modulating the metallic ink, The metallic ink is obtained by dispersing a metal colloid in a dispersion medium.

(Preparation step of dispersion medium)
In this step, a dispersion medium for modulating the metallic ink is prepared. Specifically, the dispersion medium having the distance Dc and the distance Ds in the above range is prepared based on the HSP of each of the thermoplastic resin contained in the metal colloid and the region where the metal pattern is formed. The distance Dc and the distance Ds are adjusted, for example, by selecting the type of dispersion medium and/or adjusting the mixing ratio of the plurality of dispersion media. Further, the predetermined dispersion medium may be prepared such that the distance Dc and the distance Ds are within the above range, and the plurality of dispersion mediums may be mixed according to the determined dispersion medium mixing ratio, thereby preparing the dispersion medium.

By the preparation step including the dispersion medium in the production method, high stability of the metal colloid in the obtained metal ink can be ensured, and dissolution of the substrate (thermoplastic resin) when applied to the region containing the thermoplastic resin of the substrate can be suppressed.

(Metal ink modulation step)
In this step, as long as the metal ink in which the metal colloid is dispersed in the dispersion medium can be prepared. The metallic ink can be prepared, for example, by mixing constituent components of the metallic ink (for example, metal particles and a dispersion medium). In order to disperse the constituent components more uniformly, a well-known agitator, a mixer, or the like can be used.

The order in which the constituents are mixed is not particularly limited. For example, a part of the components may be previously mixed, and the remaining components may be added and further mixed. Each component can be added at one time or added several times. The dispersing agent may be added when the metal particles are mixed with the dispersion medium, or may be mixed with the dispersion medium after being coordinated with the metal particles. The timing of adding other components (polymerization-reactive compound, polymerization initiator, and/or additives, etc.) is also not particularly limited.

In a preferred embodiment, the step of preparing the metallic ink comprises the steps of: coordinating the dispersing agent with the metal particles to form a metal colloid; and dispersing the metal colloid in the dispersion medium to obtain a metallic ink.

In the step of producing the metal colloid, for example, the dispersing agent can be coordinated to the metal particles by mixing the metal particles, the dispersing agent, and the liquid medium. Other components (additives (adhesives, etc.), etc.) may also be added in this step as needed.

The liquid medium is preferably a medium (solvent) which is liquid at room temperature (25 ° C) in which the dispersing agent is dissolved. The liquid medium can be selected depending on the type of the dispersant. The liquid medium is preferably an aliphatic alcohol or an aliphatic ester, but is not limited thereto. The liquid medium may be used singly or in combination of two or more. Mixing can also be carried out under heating, as necessary. The produced metal colloid can be recovered by separation from a liquid medium by centrifugal separation or the like.

In the step of obtaining a metallic ink, the metal colloid is mixed with a dispersion medium. Other components (polymerizable reactive compound, polymerization initiator, and/or additive, etc.) may be added in this step as needed. In order to disperse the metal colloid more uniformly in the dispersion medium, a known mixer, a mixer or the like can be used in this step.

[Method of Manufacturing Substrate with Metal Pattern]
A method for producing a substrate having a metal pattern includes a step of coating a metal ink on a substrate to form a metal pattern. The metal pattern forming step may include the steps of: applying a metal ink to the substrate to form a coating film; and baking the coating film to form a metal pattern (metal film). In one aspect of the invention, the use of the metal ink in the manufacturing method and the use of the metal ink for forming a metal pattern on a substrate are also included.

As described above, the substrate contains at least a thermoplastic resin in the region where the metallic ink is applied. Preferably, at least the region of the substrate to which the metallic ink is applied is formed of a thermoplastic resin. For example, the substrate may have a layer containing a thermoplastic resin on the surface (or main surface) on the side where the metal ink is applied, and the base material may include a thermoplastic resin as a whole. The substrate may have a layer containing a thermoplastic resin as a whole on the surface (or main surface) of the coated metal ink side of the substrate, or may have a thermoplastic resin in a part of the surface (or main surface) of the coated metal ink side of the substrate. Layer.

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

(metal pattern forming step)
(coating film forming step)
In the coating film forming step, a metal ink is applied to the surface of the substrate. The application of the metallic ink is not particularly limited, and it can be carried out by a known coating method (spin coating, spray coating, knife coating, screen printing, inkjet, or the like). Further, the coating film may be a pattern film such as a wiring or a filling, or may be a flat film.

The above metal ink is suitable for non-contact spraying (inkjet method, etc.) because of the high stability of the metal colloid in the metallic ink. Further, the coating by inkjet refers to non-contact spraying. The non-contact spraying is a coating method in which a metal ink is sprayed onto an ink body by using air pressure, spring elasticity, vibration of a piezoelectric element (piezoelectric element), or the like, for example, using mechanical or piezoelectric non-contact. The spray dispenser is used for coating. Non-contact spraying is also suitable for forming a wiring pattern on a surface of a three-dimensional shaped object, or making a multilayer substrate or the like. Here, the three-dimensional shaped object refers to a material that becomes a substrate of a circuit member having a three-dimensional structure.

(drying step)
The substrate having the coating film obtained in the coating film forming step can be dried as needed before the firing step. The drying conditions can be appropriately determined depending on the constituent components of the metallic ink and the like. In the drying step, it is preferred to remove volatile components (dispersion medium, etc.).
The drying temperature is not particularly limited and can be carried out at a temperature at which volatile components can be removed. The drying temperature is preferably lower than the firing temperature described later.

(burning step)
In the baking step, the substrate having the coating film obtained in the coating film forming step is fired. The metal particles contained in the coating film are fused by firing, and the electrical resistance of the obtained metal film can be greatly reduced. When it is a metal nanoparticle, since the nanometer size effect of the particle is melted at a temperature lower than the melting point of the metal, the effect of sufficiently reducing the electrical resistance of the metal film can be obtained even at a lower temperature.

The baking can be appropriately selected depending on the kind of the metal particles, and can be carried out, for example, at 50 ° C or higher and 250 ° C or lower, or at 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 carbon number is used as a dispersing agent, a metal film can be formed even under mild conditions. In this case, the baking 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.

The firing may also be carried out in the presence of a reducing agent.
The firing can be carried out in an inert gas atmosphere or in the atmosphere.
The firing time is not particularly limited and may be, for example, 5 minutes or longer and 120 minutes or shorter.

When a person activated by thermal action is used as a polymerization initiator, the polymerization-reactive compound may be polymerized by activation by heat applied in a drying step and/or a calcination step. When a person activated by light action is used as a polymerization initiator, it is preferred 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 can also be carried out under light irradiation.

[Examples]
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 isobutyl alcohol, and 100 g of dodecylamine (dispersant) were mixed. The obtained mixture was heated to a temperature of 100 ° C and refluxed for 5 hours. The solid components in the obtained mixture were collected by centrifugation and recovered. The recovered solid component was washed three times with methanol, and then centrifuged to recover silver nanoparticles having dodecylamine coordinated thereto. The mass ratio of the silver nanoparticles and the dodecylamine coordinated to the silver nanoparticles is 100:0.5.

The recovered silver nanoparticles were dispersed in diethylene glycol monobutyl ether using three rolls, thereby dispersing the dispersion paste. The obtained dispersion paste was applied to a substrate by spin coating, and an SEM photograph of silver nanoparticles was taken. The average particle diameter of the silver nanoparticles was calculated from the captured image by the above method and found to be about 40 nm.

(2) Preparation of Metal Ink Using the homogenizer, the metal colloid containing the silver nanoparticles collected in the above (1) was dispersed in the dispersion medium shown in Table 2, and then filtered using a 1 μm mesh disk filter to prepare a metallic ink. The concentration of the metal colloid in the metal ink was 40% by mass.

(3) Evaluation The following evaluations were performed.
(a) Determination of HSP, and calculation of distances Dc and Ds
The HSP of each of the dispersion medium and the metal colloid was determined by the above procedure using a metallic ink. 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, a plate-like substrate (substrate A) formed of a polycarbonate resin (manufactured by Teijin Co., Ltd., Panlite L-1225Y) and an acrylonitrile styrene butadiene resin (UMG ABS (manufactured by U.S.), UMG ABS EX18A) 11001) The formed plate-shaped substrate (substrate B) was obtained for each HSP according to the above procedure. Both substrates had dD of 18.4, dP of 10.1, and dH of 2.4. Furthermore, the HSP computing software uses HSPiP 4th Edition 4.1.07.
Thus, the distances Dc and Ds are calculated by the HSP.

(b) Dispersion stability After the metal ink was stored at 25 ° C for one month, the presence or absence of precipitation was visually observed, and the evaluation was carried out based on the following criteria.
A: Confirm that there is no precipitation.
B: Confirmation of precipitation.

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

[Table 2]

As shown in Table 2, in the examples in which the distance Dc of the HSP was 10 MPa ^0.5 or less and the distance Ds was 10 MPa ^0.5 or more, the high dispersion stability of the metal colloid was ensured. Also, the volume resistivity is also lowered. The reason for this is considered to be that the substrate is inhibited from being dissolved by the metallic ink.

On the other hand, in Comparative Examples 1 and 2 in which the distance Dc of the HSP exceeded 10 MPa ^0.5 , precipitation was confirmed in the metallic 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 became extremely large. The reason for this is considered to be that the dissolution of the substrate becomes remarkable.

Further, although the above embodiments show cases of using a substrate comprising a polycarbonate resin and the styrene resin, but if the HSP and Dc Ds is 10MPa ^0.5 or less, even if containing a polyester resin (e.g. polyethylene terephthalate When a substrate of another thermoplastic resin such as a butylene formate resin (for example, Duranex 2002 manufactured by Wintech Polymer Co., Ltd.) is used, it is confirmed that the same or similar effects as those of the above examples can be obtained.

While the presently preferred embodiments of the invention have been described, the invention Various changes and modifications will become apparent to those skilled in the <RTIgt; Therefore, the scope of the appended claims is intended to cover all modifications and alternatives

INDUSTRIAL APPLICABILITY According to the metal ink of 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 substrate having a region containing a thermoplastic resin. Further, a wiring pattern may be formed on the surface of the three-dimensional shaped object, or a multilayer substrate or the like may be produced.

Claims (15)

A metal ink for coating a substrate to form a metal pattern, comprising a metal colloid and a dispersion medium, wherein at least a region in which the metal pattern is formed in the substrate comprises a thermoplastic resin, the dispersion medium and the metal colloid The distance Dc of the Hansen solubility parameter is 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa ^0.5 or more. The metal ink according to claim 1, wherein the thermoplastic resin comprises at least one selected from the group consisting of polycarbonate resins, styrene resins, and polyester resins. The metal ink of claim 1 or 2, wherein the aforementioned distance Dc is 8.6 MPa ^0.5 or less. The metallic ink according to any one of claims 1 to 3, wherein the aforementioned distance Dc is 3 MPa ^0.5 or more. The metallic ink according to any one of claims 1 to 4, wherein the aforementioned distance Ds is 15 MPa ^0.5 or less. The metallic ink according to any one of claims 1 to 5, wherein 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. The metallic ink according to any one of claims 1 to 6, wherein 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. Above and below 23. The metal ink according to any one of claims 1 to 7, wherein the metal contained in the metal colloid is selected from at least one selected from the group consisting of silver, a silver alloy, copper, and a copper alloy. The metal ink according to any one of claims 1 to 8, wherein the metal colloid comprises metal nanoparticles and a dispersing agent coordinated to the metal nanoparticles. The metal nanoparticles have an average particle diameter of 5 nm or more and 400 nm or less. The metallic ink of claim 9, wherein the aforementioned dispersing agent comprises a C _4-16 alkylamine. The metal ink according to any one of claims 1 to 10, wherein a ratio of the dispersion medium in the metal ink is 25% by mass or more and 95% by mass or less. A metal ink system comprising a metal colloid and a dispersion medium and applied to a substrate to form a metal pattern, wherein at least a region in which the metal pattern is formed in the substrate comprises a thermoplastic resin; The manufacturing method comprises the steps of: preparing the dispersion medium, the distance Dc between the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin It is 10 MPa ^0.5 or more; and the step of preparing a metallic ink in which the metal colloid is dispersed in the dispersion medium. The method of producing a metallic ink according to claim 12, wherein the thermoplastic resin comprises at least one selected from the group consisting of a polycarbonate resin, a styrene resin, and a polyester resin. A method for producing a substrate having a metal pattern, comprising the steps of applying a metal ink to a substrate to form a metal pattern, wherein at least a region in which the metal pattern is formed in the substrate comprises a thermoplastic resin, and the metal ink comprises a metal colloid and In the dispersion medium, the distance Dc between the dispersion medium and the Hansen solubility parameter of the metal colloid is 10 MPa ^0.5 or less, and the distance Ds between the dispersion medium and the Hansen solubility parameter of the thermoplastic resin is 10 MPa ^0.5 or more. A method of producing a substrate having a metal pattern according to claim 14, wherein the thermoplastic resin comprises at least one selected from the group consisting of polycarbonate resins, styrene resins, and polyester resins.