JP6497129B2 - Dispersant and method for producing the same, ink, and method for forming conductive pattern - Google Patents

Description

  The present invention relates to a dispersant and a method for producing the same, an ink, and a method for forming a conductive pattern.

Conventionally, photolithography, etching, etc. have been mainly used as a method for forming conductive patterns such as wiring and antennas on a substrate, but there are problems in terms of the number of process steps, material use efficiency, etc. There are high manufacturing costs.
Then, the method of forming a conductive pattern using printing methods, such as an inkjet printing method, is known (for example, refer patent document 1).

The inkjet printing method is a method in which ink is printed on a substrate using the inkjet method, and then dried and baked.
As an ink, a nano metal ink in which metal particles having a primary particle size of the order of nm are dispersed in a dispersion medium is known.
For example, as a method of forming a conductive film, a step of depositing a film containing a plurality of copper nanoparticles on the surface of a substrate, a step of exposing at least a part of the film to make the exposed portion conductive, Has been proposed (see Patent Document 2). At this time, a conductive film is deposited from a dispersion containing copper nanoparticles, a solvent and a dispersant.
However, since the proposed method is locally heated and baked by thermal energy converted from light energy absorbed by the copper nanoparticles, the preferred range of exposure conditions for obtaining good film quality and conductivity is narrow. There is a problem.

  An object of this invention is to provide the dispersing agent of the metal particle which does not have baking shortage and excessive baking.

The above problem is solved by the “dispersant” described in the following (1).
(1) “A dispersant used in a dispersion of metal particles, a structural unit derived from a compound represented by the following general formula (1), a structural unit derived from a compound represented by the following structural formula (2), And a structural unit derived from a compound having an ionic group.

（ただし、Ｒ_１は−Ｈあるいは−ＣＨ_３、Ｒ_２は炭素数９までのアルキル基、ｘは２または３である。また、ｎは一般式（１）の分子量が１００００以下となるような整数である。）

(Where R ₁ is —H or —CH ₃ , R ₂ is an alkyl group having up to 9 carbon atoms, x is 2 or 3, and n is such that the molecular weight of general formula (1) is 10,000 or less. (It is an integer.)

」。

"

  According to the present invention, a dispersing agent for metal particles that is free from insufficient firing or excessive firing can be easily obtained.

The present invention relates to the “dispersant” described in the above (1), but as will be understood from the following detailed description, the “of the embodiment described in the following (2) to (7)” Also included are "dispersant", "dispersant manufacturing method", "ink", and "conductive pattern forming method".
(2) The ionic group in the compound having an ionic group includes any one selected from an amino group, a carboxyl group, a sulfo group, and a phospho group. Dispersant. "
(3) “A method for producing a dispersant used in a dispersion of metal particles, comprising a structural unit derived from a compound represented by the following general formula (1), a compound represented by the following structural formula (2); A method for producing a dispersant, comprising a step of polymerizing a compound having an ionic group.

（ただし、Ｒ_１は−Ｈあるいは−ＣＨ_３、Ｒ_２は炭素数９までのアルキル基、ｘは２または３である。また、ｎは一般式（１）の分子量が１００００以下となるような整数である。）

(Where R ₁ is —H or —CH ₃ , R ₂ is an alkyl group having up to 9 carbon atoms, x is 2 or 3, and n is such that the molecular weight of general formula (1) is 10,000 or less. (It is an integer.)

(4) “Ink used for forming a conductive pattern, comprising the dispersant, metal particles, and dispersion medium liquid according to (1) or (2)”.
(5) The ink according to (4) above, wherein the medium liquid contains a solvent selected from glycol ether, glycol ester, and dialkyl glycol ether as a main component.
(6) Conductivity characterized by including an application step of applying the ink according to (4) or (5) on a substrate and a baking step of baking the ink applied on the substrate. Method for forming a sex pattern. "
(7) “The method for forming a conductive pattern according to (6), wherein the baking step includes a step of photo-baking the ink applied on the base material.”

(Dispersant)
Hereinafter, the present invention will be described in detail.
The dispersant of the present invention is used for dispersing metal particles, and is a structural unit derived from a compound represented by the following general formula (1), a structural unit derived from a compound represented by the following structural formula (2), and an ionic group And a structural unit derived from a compound having

（ただし、Ｒ_１は−Ｈあるいは−ＣＨ_３、Ｒ_２は炭素数９までのアルキル基あるいはフェニル基、ｘは２または３である。また、ｎは一般式（１）の分子量が１００００以下となるような整数である。）

(However, R ₁ is —H or —CH ₃ , R ₂ is an alkyl group or phenyl group having up to 9 carbon atoms, x is 2 or 3. n is a molecular weight of 10,000 or less in the general formula (1). It is an integer such that

  The polymer having at least the above monomer as a constituent element becomes a comb polymer in which a side chain that is a repeating structure of an alkylene oxide extends with respect to the main chain. It is considered that this alkylene oxide part contributes to compatibility with the solvent, and is easily gasified completely during thermal decomposition and hardly remains.

<Constitutional unit derived from the compound represented by the general formula (1)>
The compound represented by the general formula (1) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, poly (ethylene glycol) methyl ether methacrylate, ethylene glycol methyl ether methacrylate, di ( Ethylene glycol) methyl ether methacrylate, ethylene glycol phenyl ether methacrylate, methacrylate triethylene glycol methyl ether, methacrylates such as poly (ethyl glycol) ethyl ether methacrylate, ethylene glycol methyl ether acrylate, ethylene glycol phenyl ether acrylate, di ( Ethylene glycol) ethyl ether acrylate, poly (ethylene glycol) methyl ether acrylate , Ethylene glycol dicyclopentenyl ether acrylate, Di (ethyl glyceryl) 2-ethyl hexyl ether acrylate, poly (propylene glyceryl) 4-nonethyl propyl ether acrylate, Poly (ethyl propyl ether) Examples include acrylates such as acrylate and poly (propylene glycol) acrylate.

<Constitutional unit derived from a compound having an ionic group>
There is no restriction | limiting in particular as an ionic group in the compound which has the said ionic group, According to the objective, it can select suitably, For example, an amino group or its salt, a carboxyl group or its salt, a sulfo group or its salt, Examples thereof include a phospho group or a salt thereof. These may be used individually by 1 type and may use 2 or more types together. Among these, an amino group, a carboxyl group, a sulfo group, and a phospho group are preferable from the viewpoint of adsorptivity to metal particles.

  There is no restriction | limiting in particular as a compound which has the said amino group, According to the objective, it can select suitably, For example, N-methylaminoethyl (meth) acrylate, N-ethylaminoethyl (meth) acrylate, N, N -Dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl acrylate, N, N-di-tert-butylaminoethyl acrylate, N-phenylaminoethyl methacrylate, N , N-diphenylaminoethyl methacrylate, allylamine, 4-aminostyrene, 4-N, N-dimethylaminostyrene, N-methylaminoethylstyrene, dimethylaminoethoxystyrene, diphenylaminoethylstyrene, N-phenylaminoethylstyrene, -N- piperidyl ethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinyl-6-methyl-pyridine.

  The compound having a carboxyl group is not particularly limited and may be appropriately selected depending on the purpose. For example, (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, Cinnamic acid, crotonic acid, vinyl benzoic acid, 2-methacryloxyethyl succinic acid, 2-methacryloxyethyl maleic acid, 2-methacryloxyethyl hexahydrophthalic acid, 2-methacryloxyethyl trimellitic acid and the like can be mentioned.

  The compound having a sulfo group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid. Is mentioned.

  The compound having a phospho group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 3- (meth) acryloxypropylphosphonic acid.

  Since the dispersant has a structural unit derived from the compound represented by the structural formula (2), good conductivity can be obtained in a wide exposure energy range. Although details are unknown, it is probably because the firing proceeds well due to the good adhesion of the compound represented by the structural formula (2) to the substrate and the ability to retain heat energy due to heat resistance. .

Since the dispersant has a group represented by the following general formula (A) in the side chain, it is considered that the dispersant is easily decomposed during firing and can form a conductive thin film or pattern having a small volume resistivity.
In addition, it is thought that group represented by general formula (A) contributes also to the solubility with respect to the dispersion medium which disperse | distributes a metal particle.

（ただし、ｘは、２又は３であり、ｎは、２以上の自然数である。）

(However, x is 2 or 3, and n is a natural number of 2 or more.)

Since the dispersant has a structural unit derived from a compound having an ionic group, the dispersant can be adsorbed on the metal particles. In addition, since the said dispersing agent has a polymer chain, it can suppress aggregation of a metal particle by a steric hindrance.
There is no restriction | limiting in particular in the number average molecular weight of the said dispersing agent, According to the objective, it can select suitably, For example, 5000-100000 are preferable.

(Method for producing dispersant)
The method for producing a dispersant of the present invention includes a polymerization step, and further includes other steps as necessary.

<Polymerization process>
The polymerization step includes a step of polymerizing a composition containing the compound represented by the general formula (1), the compound represented by the structural formula (2), and the compound having the ionic group.

  The composition may contain other components in addition to the compound represented by the general formula (1), the compound represented by the structural formula (2), and the compound having the ionic group. There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a polymerization initiator, a solvent, etc. are mentioned.

  The molar ratio A / B of the compound A represented by the general formula (1) with respect to the compound B having the ionic group in the synthesis of the dispersant is not particularly limited, and the adsorptivity of the dispersant to the metal particles and Although it can determine suitably from the balance of steric hindrance, 9-999 are preferable and, as for the said molar ratio A / B, 20-100 are more preferable. The molar ratio C of the compound C represented by the structural formula (2) to the sum of the compound A represented by the general formula (1), the compound B having the ionic group, and the compound C represented by the structural formula (2). / (A + B + C) is preferably 0.001 to 0.2. Within this range, good film quality can be obtained, and the function as a dispersant is suitably exhibited, so that it is preferable to easily obtain the storage stability of the ink.

  When the ionic group in the compound having an ionic group is a salt of an amino group, a carboxyl group, a sulfo group or a phospho group, the compound represented by the general formula (1) and the amino group, carboxyl group, sulfo group The dispersing agent may be synthesized by polymerizing a composition containing a compound having a group or a phospho group and then neutralizing the composition.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a neutralization process, a refinement | purification process, etc. are mentioned.

(ink)
The ink of the present invention can be used, for example, for forming a conductive pattern, and contains the dispersant, metal particles, and dispersion medium liquid of the present invention, and further contains other components as necessary. .

<Dispersant>
The content of the dispersant of the present invention in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 part by mass to 20 parts by mass with respect to 100 parts by mass of the dispersion medium. .

<Dispersion medium>
The dispersion medium liquid is not particularly limited as long as the metal particles can be dispersed, and can be appropriately selected according to the purpose. Examples thereof include an organic solvent. The organic solvent is preferably a polar organic solvent from the viewpoint of the solubility of the dispersant, and more preferably a monoalkyl glycol ether, a glycol monoalkyl ether ester or a dialkyl glycol ether.

  The monoalkyl glycol ether is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol Ethylene glycol ethers such as monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol Monomethyl ether Pyrene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol And propylene glycol ethers such as propylene glycol monobutyl ether.

  There is no restriction | limiting in particular as said glycol monoalkyl ether ester, According to the objective, it can select suitably, For example, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate etc. are mentioned.

  The dialkyl glycol ether is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol Examples include dimethyl ether.

<Metal particles>
The metal particles are not particularly limited as long as a conductive pattern can be formed, and examples thereof include copper particles, silver particles, and nickel particles.

The average particle diameter of the metal particles is preferably 2 nm to 100 nm, and more preferably 5 nm to 50 nm.
The average particle size of the metal particles can be measured using, for example, a dynamic light scattering method.

  There is no restriction | limiting in particular in content of the said metal particle in the said ink, Although it can select suitably according to the objective, 10 mass parts-50 mass parts are preferable with respect to 100 mass parts of said dispersion media.

  The disperser used when dispersing the metal particles in the dispersion medium is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a homogenizer, a ball mill, a sand mill, and an attritor.

(Method for forming conductive pattern)
The method for forming a conductive pattern of the present invention includes a coating process and a baking process, and further includes other processes as necessary.
The conductive pattern includes a conductive thin film on which no pattern is formed.

<Application process>
The coating step is a step of coating the ink of the present invention on a substrate.

As the base material is not particularly limited and may be appropriately selected depending on the intended purpose, e.g., a glass substrate, a quartz substrate, a silicon substrate, SiO ₂ film-coated silicon substrate, a polyethylene terephthalate substrate, a polycarbonate Examples thereof include polymer base materials such as base materials, polystyrene base materials, and polymethylmethacrylate base materials, films with an ink receiving layer (OHP sheet), and ink jet recording media such as paper with an ink receiving layer. These may be used individually by 1 type and may use 2 or more types together.
The base material may be appropriately synthesized or a commercially available product may be used.
There is no restriction | limiting in particular as thickness of the said base material, According to the objective, it can select suitably, 100 micrometers or more are preferable and 500 micrometers or more are more preferable.

  The ink application method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a spin coating method, an ink jet method, a gravure printing method, and a screen printing method. Among these, the inkjet method is preferable because direct patterning is possible.

<Baking process>
The firing step is a step of firing the ink applied on the substrate.
When the ink applied on the substrate is baked, the gap between the metal particles can be eliminated and the ohmic contact can be formed by combining the metal particles.

  The method for firing the ink applied on the substrate is not particularly limited as long as the metal particles can be combined, and can be appropriately selected according to the purpose. Examples include firing. Among these, light baking is preferable from the viewpoint that damage to the substrate can be suppressed. The temperature at which the ink applied on the substrate is photo-baked is preferably 200 ° C. or lower, and more preferably 150 ° C. or lower. There is no restriction | limiting in particular as a light source used at the time of the said photobaking, According to the objective, it can select suitably, For example, a xenon lamp etc. are mentioned. In addition, it is preferable to heat-dry before baking the ink apply | coated on the said base material.

The conductive pattern obtained by the method for forming a conductive pattern of the present invention using the ink of the present invention containing the dispersant of the present invention has a low volume resistivity and excellent conductivity. The volume resistivity of the conductive pattern is preferably 1 × 10 ⁻⁴ Ω · cm or less, and more preferably 1 × 10 ⁻⁵ Ω · cm or less. The volume resistivity is calculated by measuring the electrical resistance and thickness of the conductive pattern using a resistivity meter (eg, Loresta, manufactured by Mitsubishi Chemical Corporation) and a surface shape measuring device (eg, Alphastep, manufactured by KLA). can do.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Example 1 (Synthesis Example 1) to Example 8 (Synthesis Example 8); Synthesis Examples 1 to 8 of Polymer Dispersant]
In a reaction vessel equipped with a stirrer, thermometer and reflux condenser, 300 parts of ethanol was taken and heated to 60 ° C. under a nitrogen purge. The solution which consists of 1 part of azobisdimethylvaleronitrile which is a monomer and a polymerization initiator which are shown in the following table in this was dripped over 1 hour. Subsequently, stirring was continued at the same temperature for 5 hours to complete the reaction. By evaporating ethanol as a solvent from the obtained resin solution with an evaporator, the polymer dispersant of the present invention suitable for dispersing metal particles was obtained.

<Average particle diameter of ink>
The average particle size of the ink was measured using a thick particle size analyzer FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.).

[Example 9: Ink Preparation Example 1]
10 parts by mass of dispersant 1, 40 parts by mass of copper particles QSI-Nano Copper Powder (manufactured by QuantumSphere), and 100 parts by mass of ethylene glycol monoethyl ether were ultrasonically dispersed for 10 minutes, and then a high-speed mixer fill mix (primics) For 10 minutes. Next, coarse particles were removed using a filter having a pore size of 1 μm to obtain an ink having an average particle size of 70 nm.

Example 10 Ink Preparation Example 2
In Example 9, 2 parts by weight of Dispersant 2 was used in place of 10 parts by weight of Dispersant 1, and diethylene glycol monoethyl ether was used in place of ethylene glycol monoethyl ether. Thus, an ink having an average particle diameter of 82 nm was obtained.

Example 11 Ink Preparation Example 3
In Example 9, 10 parts by weight of dispersant 3 was used instead of 10 parts by weight of dispersant 1, and triethylene glycol dimethyl ether was used instead of ethylene glycol monoethyl ether. Thus, an ink having an average particle diameter of 73 nm was obtained.

Example 12 Ink Preparation Example 4
In Example 9, 10 parts by weight of Dispersant 1 was used in place of 10 parts by weight of Dispersant 1, and diethylene glycol monobutyl ether acetate was used in place of ethylene glycol monoethyl ether. Thus, an ink having an average particle diameter of 78 nm was obtained.

[Comparative Example 1]
In Example 9, an ink having an average particle diameter of 68 nm was obtained in the same manner as in Example 9 except that 10 parts by mass of Dispersant 5 was used instead of Dispersant 1.

[Comparative Example 2]
In Example 10, an ink having an average particle diameter of 82 nm was obtained in the same manner as in Example 10 except that 2 parts by mass of the dispersant 6 was used instead of the dispersant 2.

[Comparative Example 3]
In Example 11, an ink having an average particle diameter of 75 nm was obtained in the same manner as in Example 11 except that 10 parts by mass of the dispersant 7 was used instead of the dispersant 3.

[Comparative Example 4]
In Example 12, an ink having an average particle diameter of 77 nm was obtained in the same manner as in Example 12 except that 2 parts by mass of the dispersant 8 was used instead of the dispersant 4.

  Next, using each ink produced, a conductive pattern was formed as follows, and the volume resistivity was measured. The results are shown in Table 2.

<Formation of conductive pattern>
After ink was patterned on a film with an ink receiving layer (OHP sheet) using an inkjet coating apparatus (manufactured by Ricoh Co., Ltd.), the dispersion medium was evaporated using a 120 ° C. hot plate. Next, light of the following energy was irradiated using a xenon flash pulse (SINTERON, manufactured by XENON) to form a conductive pattern. Furthermore, the electrical resistivity and thickness of the conductive pattern were measured using a resistivity meter (Loresta, manufactured by Mitsubishi Chemical Corporation) and Alpha Step (manufactured by KLA), and the volume resistivity was calculated.

From the result of Table 2, the ink of Examples 9-12 obtained the conductive pattern with a low volume resistivity in the wide irradiation energy range.
On the other hand, the inks of Comparative Examples 1 to 4 had a narrow irradiation energy range in which a low volume resistivity was obtained.

JP 2008-60544 A Special table 2010-528428 gazette

Claims (7)

A dispersant used in a dispersion of metal particles, comprising a structural unit derived from a compound represented by the following general formula (1), a structural unit derived from a compound represented by the following structural formula (2), and an ionic group And a structural unit derived from the compound.

(Where R ₁ is —H or —CH ₃ , R ₂ is an alkyl group having up to 9 carbon atoms, x is 2 or 3, and n is such that the molecular weight of general formula (1) is 10,000 or less. (It is an integer.)

  2. The dispersant according to claim 1, wherein the ionic group in the compound having an ionic group includes one selected from an amino group, a carboxyl group, a sulfo group, and a phospho group. A method for producing a dispersant used in a dispersion of metal particles, comprising a compound represented by the following general formula (1), a compound represented by the following structural formula (2), and a compound having an ionic group The manufacturing method of the dispersing agent characterized by having the process to superpose | polymerize.

(Where R ₁ is —H or —CH ₃ , R ₂ is an alkyl group having up to 9 carbon atoms, x is 2 or 3, and n is such that the molecular weight of general formula (1) is 10,000 or less. (It is an integer.)

  An ink used for forming a conductive pattern, comprising the dispersant according to claim 1, metal particles, and a dispersion medium liquid. The ink according to claim 4, wherein the medium liquid contains a solvent selected from glycol ether, glycol ester, and dialkyl glycol ether as a main component.   A method for forming a conductive pattern, comprising: an application step of applying the ink according to claim 4 on a substrate; and a baking step of baking the ink applied on the substrate.   The method for forming a conductive pattern according to claim 6, wherein the baking step includes a step of light baking the ink applied on the base material.