JP5861480B2 - Manufacturing method of metal nanowire - Google Patents

Description

  The present invention relates to a method for producing metal nanowires.

  Since metal nanowires have high conductivity, they are used in the field of electrodes. As a method for producing this metal nanowire, for example, a method for producing silver nanowire using silver nitrate, ethylene glycol and 1-butyl-3-methylimidazolium methyl sulfate has been reported (Patent Document 1).

International Publication No. 2010/058941 Pamphlet

  However, the silver nanowires obtained by the above-described manufacturing method are a plurality of bundles assembled together (that is, those containing a lot of aggregates), and can contain a lot of particulate silver nanomaterials. It was difficult to obtain a single silver nanowire (that is, a silver nanowire having a small degree of aggregation and a uniform shape).

  Then, an object of this invention is to provide the manufacturing method from which a single metal nanowire is obtained easily.

  As a result of intensive studies, the present inventors have made the present invention.

  That is, this invention provides the manufacturing method of metal nanowire including reacting a metal salt in presence of a reducing agent, a polar polymer, and the compound represented by following formula (1).

（式中、
X^-は、ハロゲン化物イオンを表す。Ｒ¹およびＲ²は、それぞれ独立に、水素原子または置換若しくは非置換の１価の炭化水素基を表し、複数あるＲ²は、同一でも異なっていてもよい。）

(Where
X ⁻ represents a halide ion. R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and a plurality of R ² may be the same or different. )

  According to the method for producing metal nanowires of the present invention, a single metal nanowire can be produced.

2 is a photograph taken with a scanning electron microscope image (magnification: 5,000 times) of the silver nanowire obtained in Example 1. FIG. 4 is a photograph taken with a scanning electron microscope image (magnification: 5,000 times) of the silver nanowire obtained in Example 2. FIG. 2 is a photograph taken with a scanning electron microscope image (magnification: 5,000 times) of the silver nanomaterial obtained in Comparative Example 1. FIG. 4 is a photograph taken with a scanning electron microscope image (magnification: 5,000 times) of the silver nanomaterial obtained in Comparative Example 2. FIG. It is a photograph by the scanning electron microscope image (magnification: 5,000 times) of the silver nanowire obtained in Example 3. It is the photograph by the biological microscope (magnification: 1,000 times) of the silver nanowire obtained in Example 4.

  The manufacturing method of the metal nanowire of this invention is a manufacturing method including making a metal salt react in presence of a reducing agent, a polar polymer, and the compound represented by following formula (1).

（式中、X^-は、ハロゲン化物イオンを表す。Ｒ¹およびＲ²は、それぞれ独立に、水素原子または置換若しくは非置換の１価の炭化水素基を表し、複数あるＲ²は、同一でも異なっていてもよい。）

(In the formula, X ⁻ represents a halide ion. R ¹ and R ² each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and a plurality of R ² may be the same. May be different.)

  In the present specification, the “metal nanowire” has a nano-unit diameter (the shortest diameter is 1000 nm or less) present in the product (usually a mixture) obtained by the production method of the present invention. Means a wire-like individual. Metal nanowires are electron microscopes (scanning electron microscopes (hereinafter referred to as “SEM”) and transmission electron microscopes (hereinafter referred to as “TEM”)) or optical microscopes (for example, metal microscopes, biological microscopes, It can be visually confirmed from photographs taken with a stereo microscope, a polarizing microscope, a fluorescence microscope, a laser microscope, a microscope, etc.).

The shortest diameter of the metal nanowire is usually 1 nm or more, and since conductivity is good, 5 nm or more is preferable, 10 nm or more is more preferable, and 30 nm or more is more preferable.
The longest diameter of the metal nanowire is usually more than 1000 nm, but since the conductivity is good, it is preferably 1300 nm or more, more preferably 1600 nm or more, still more preferably 2000 nm or more, and particularly preferably 2500 nm. Above, especially preferably 3000 nm or more. The longest diameter of the metal nanowire is usually 1 cm or less, preferably 1 mm or less, more preferably 0.5 mm or less, still more preferably 0.3 mm or less, and particularly preferably 0.1 mm or less. It is.

The ratio between the longest diameter and the shortest diameter of metal nanowire (hereinafter referred to as “aspect ratio”) is usually 1.5 or more, and is preferably 5 or more, more preferably because conductivity is improved. It is 10 or more, more preferably 20 or more, particularly preferably 1 × 10 ² or more, and particularly preferably 3 × 10 ² or more.

Since the aspect ratio of the metal nanowire is usually 1 × 10 ⁷ or less and the dispersibility is good, it is preferably 1 × 10 ⁶ or less, more preferably 1 × 10 ⁵ or less, and still more preferably 1 × 10 ⁴ or less, particularly preferably 1 × 10 ³ or less.

The aspect ratio of the metal nanowire is preferably ²⁰ to 1 × 10 ⁵ , more preferably 1 × 10 ² to 1 × 10 ⁴ when the upper limit and the lower limit are described together.

As described above, the aspect ratio means the ratio of the longest diameter to the shortest diameter (longest diameter / shortest diameter) in metal nanomaterials such as metal nanowires, and this aspect ratio has a distribution. Is the arithmetic mean. The aspect ratio of a metal nanomaterial such as a metal nanowire can be specified using the above-mentioned photograph taken with an electron microscope or an optical microscope.
That is, the aspect ratio is, for example, the ratio of the length (longest diameter) of the metal nanowire to the diameter (shortest diameter).

  As a metal which comprises metal nanowire, since stability as a metal becomes favorable, a transition metal is preferable, a periodic table group 11 metal is more preferable, and silver is still more preferable.

  The metal nanowires obtained by the production method of the present invention are useful in the fields of catalysts such as industrial catalysts (for example, high surface area catalysts, low-temperature sinterable electrodes), conductive films, wirings, and coating-type electrodes.

  ・ Method of manufacturing metal nanowires

In the formula (1), X ⁻ is a halide ion, preferably F ⁻ , Cl ⁻ , Br ⁻ and I ⁻ , more preferably Cl ⁻ and Br ^{−, and} still more preferably Cl ⁻ .

In the formula (1), examples of the monovalent hydrocarbon group represented by R ¹ include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, an arylalkenyl group, and an arylalkynyl group. An alkyl group, an alkenyl group, an aryl group, an arylalkyl group, and an arylalkenyl group are preferable, an alkyl group, an alkenyl group, and an arylalkyl group are more preferable, and an alkyl group is still more preferable.

  The alkyl group may be linear, branched or cyclic. The number of carbon atoms of the linear and branched alkyl groups is usually 1 to 50, preferably 1 to 20, and more preferably 1 to 6. The number of carbon atoms of the cyclic alkyl group is usually 3 to 50, preferably 3 to 20. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, cyclohexyl, heptyl, octyl, and nonyl. Group, decyl group, lauryl group and the like. A hydrogen atom in the alkyl group may be substituted with a fluorine atom. Examples of the alkyl group substituted with a fluorine atom include a trifluoromethyl group, a pentafluoroethyl group, a perfluorobutyl group, a perfluorohexyl group, and a perfluorooctyl group.

  The alkenyl group may be linear, branched or cyclic. The number of carbon atoms of the linear and branched alkenyl groups is usually 2 to 50, preferably 2 to 20. The number of carbon atoms of the cyclic alkenyl group is usually 3 to 50, preferably 3 to 20. Examples of the alkenyl group include ethenyl group, propenyl group, 3-butenyl group, 2-butenyl group, 2-pentenyl group, 2-hexenyl group, 2-nonenyl group and 2-dodecenyl group.

  The alkynyl group may be linear, branched or cyclic. The number of carbon atoms of the linear and branched alkynyl groups is usually 2 to 50, preferably 2 to 20. The number of carbon atoms of the cyclic alkynyl group is usually 3 to 50, preferably 3 to 20. Examples of the alkynyl group include ethynyl group, 1-propynyl group, 3-butynyl group, 4-pentynyl group, and 5-hexynyl group.

The aryl group is a remaining atomic group obtained by removing one hydrogen atom directly from a carbon atom constituting an aromatic ring from an aromatic hydrocarbon, having a condensed ring, an independent benzene ring and a condensed ring. It includes those in which two or more selected rings are directly bonded or those bonded via a vinylene group or the like.
The number of carbon atoms of the aryl group is usually 6 to 60, preferably 6 to 48. The number of carbon atoms does not include the number of carbon atoms of the substituent described later. Examples of the aryl group include a phenyl group, C ₁ -C ₁₂ alkoxyphenyl group ( "C ₁ -C ₁₂ alkoxy" means that number of carbon atoms in the alkoxy moiety is 1 to 12. Hereinafter, the same.) , C ₁ -C ₁₂ alkylphenyl group (“C ₁ -C ₁₂ alkyl” indicates that the alkyl moiety has 1 to 12 carbon atoms, the same shall apply hereinafter), 1-naphthyl group, 2 - naphthyl, 1-anthracenyl group, 9-anthracenyl group and the like, C ₁ -C ₁₂ alkoxyphenyl group, is C ₁ -C ₁₂ alkylphenyl group are preferable. A hydrogen atom in the aryl group may be substituted with a fluorine atom. Examples of the aryl group substituted with a fluorine atom include a pentafluorophenyl group.
The C ₁ -C ₁₂ alkoxyphenyl group, methoxyphenyl group, ethoxyphenyl group, propyloxyphenyl group, isopropyloxyphenyl group, butoxyphenyl group, isobutoxyphenyl group, sec- butoxyphenyl, tert- butoxyphenyl, Pentyloxyphenyl group, hexyloxyphenyl group, cyclohexyloxyphenyl group, heptyloxyphenyl group, octyloxyphenyl group, 2-ethylhexyloxyphenyl group, nonyloxyphenyl group, decyloxyphenyl group, 3,7-dimethyloctyloxyphenyl Group, lauryloxyphenyl group and the like.
The C ₁ -C ₁₂ alkylphenyl group include a methylphenyl group, ethylphenyl group, dimethylphenyl group, propylphenyl group, mesityl group, methylethylphenyl group, isopropylphenyl group, butylphenyl group, isobutylphenyl group, tert- butyl Examples thereof include a phenyl group, a pentylphenyl group, an isoamylphenyl group, a hexylphenyl group, a heptylphenyl group, an octylphenyl group, a nonylphenyl group, a decylphenyl group, and a dodecylphenyl group.

The arylalkyl group is a combination of the aryl group and the alkyl group. The number of carbon atoms in the arylalkyl group is usually 7 to 60, preferably 7 to 30. The number of carbon atoms does not include the number of carbon atoms of the substituent described later. The aryl alkyl group, a phenyl -C ₁ -C ₁₂ alkyl group, C ₁ -C ₁₂ alkoxyphenyl -C ₁ -C ₁₂ alkyl group, C ₁ -C ₁₂ alkylphenyl -C ₁ -C ₁₂ alkyl group, 1- naphthyl -C ₁ -C ₁₂ alkyl group, 2-naphthyl -C ₁ -C ₁₂ alkyl group, and the like.

The arylalkenyl group is a combination of the aryl group and an alkenyl group. The number of carbon atoms of the arylalkenyl group is usually 8 to 60, preferably 8 to 30. The number of carbon atoms does not include the number of carbon atoms of the substituent described later. As the arylalkenyl group, a phenyl-C ₂ -C ₁₂ alkenyl group (“C ₂ -C ₁₂ alkenyl” indicates that the alkenyl moiety has 2 to 12 carbon atoms. The same shall apply hereinafter). C ₁ -C ₁₂ alkoxyphenyl -C ₂ -C ₁₂ alkenyl group, C ₁ -C ₁₂ alkylphenyl -C ₂ -C ₁₂ alkenyl group, 1-naphthyl -C ₂ -C ₁₂ alkenyl group, 2-naphthyl -C ₂ -C ₁₂ alkenyl groups and the like, C ₁ -C ₁₂ alkoxyphenyl -C ₂ -C ₁₂ alkenyl group, a C ₂ -C ₁₂ alkylphenyl -C ₂ -C ₁₂ alkenyl group are preferred.

The arylalkynyl group is a combination of the aryl group and an alkynyl group. The number of carbon atoms of the arylalkynyl group is usually 8 to 60, preferably 8 to 30. The number of carbon atoms does not include the number of carbon atoms of the substituent described later. As the arylalkynyl group, a phenyl-C ₂ -C ₁₂ alkynyl group (“C ₂ -C ₁₂ alkynyl” indicates that the alkynyl moiety has 2 to 12 carbon atoms; the same applies hereinafter). C ₁ -C ₁₂ alkoxyphenyl -C ₂ -C ₁₂ alkynyl group, C ₁ -C ₁₂ alkylphenyl -C ₂ -C ₁₂ alkynyl group, 1-naphthyl -C ₂ -C ₁₂ alkynyl group, 2-naphthyl -C ₂ -C ₁₂ alkynyl groups and the like, C ₁ -C ₁₂ alkoxyphenyl -C ₂ -C ₁₂ alkynyl and C ₁ -C ₁₂ alkylphenyl -C ₂ -C ₁₂ alkynyl group are preferable.

Part or all of the hydrogen atoms contained in the monovalent hydrocarbon group represented by R ¹ are alkoxy groups, alkylthio groups, aryloxy groups, arylthio groups, arylalkoxy groups, arylalkylthio groups, amino groups, substituted amino groups. Group, silyl group, substituted silyl group, halogen atom, acyl group, acyloxy group, imine residue, amide group, acid imide group, monovalent heterocyclic group, hydroxyl group, aldehyde group, carboxyl group, substituted oxycarbonyl group, It may be substituted with a substituent such as a cyano group or a nitro group. In addition, when two or more substituents exist, they may be the same or different. Here, the “monovalent heterocyclic group” means an atomic group remaining after removing one hydrogen atom from a heterocyclic compound.

  As the substituent, an alkoxy group, an aryloxy group, an arylalkoxy group, an amino group, a substituted amino group, an acyl group, an acyloxy group, an acid imide group, a cyano group, and a nitro group are preferable, and an alkoxy group, an aryloxy group, an aryl group More preferred are an alkoxy group, a substituted amino group, an acyl group, and an acyloxy group. Hereinafter, more preferred substituents will be described.

  The alkoxy group as the substituent may be linear, branched or cyclic. The number of carbon atoms of the linear and branched alkoxy groups is usually 1-20, and preferably 1-10. The number of carbon atoms of the cyclic alkoxy group is usually 3 to 20, and 3 to 10 is preferable. Examples of the alkoxy group include methoxy group, ethoxy group, propyloxy group, isopropyloxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, cyclohexyloxy group, heptyloxy Group, octyloxy group, nonyloxy group, decyloxy group, lauryloxy group and the like. A hydrogen atom in the alkoxy group may be substituted with a fluorine atom. Examples of the alkoxy group substituted with a fluorine atom include trifluoromethoxy group, pentafluoroethoxy group, perfluorobutoxy group, perfluorohexyloxy group, perfluorooctyloxy group, methoxymethyloxy group, and 2-methoxyethyloxy group. Is mentioned.

The number of carbon atoms of the aryloxy group as the substituent is usually 6 to 60, and preferably 6 to 48. The aryloxy group is a phenoxy group, C ₁ -C ₁₂ alkoxy phenoxy group, C ₁ -C ₁₂ alkylphenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, a pentafluorophenyl group and the like.
Examples of the C _{1 to} C ₁₂ alkoxyphenoxy group include a methoxyphenoxy group, an ethoxyphenoxy group, a propyloxyphenoxy group, an isopropyloxyphenoxy group, a butoxyphenoxy group, an isobutoxyphenoxy group, a sec-butoxyphenoxy group, a tert-butoxyphenoxy group, Pentyloxyphenoxy group, hexyloxyphenoxy group, cyclohexyloxyphenoxy group, heptyloxyphenoxy group, octyloxyphenoxy group, 2-ethylhexyloxyphenoxy group, nonyloxyphenoxy group, decyloxyphenoxy group, 3,7-dimethyloctyloxyphenoxy Group, lauryloxyphenoxy group and the like.
The C ₁ -C ₁₂ alkylphenoxy group, methylphenoxy group, ethylphenoxy group, dimethylphenoxy group, propylphenoxy group, 1,3,5-methylphenoxy group, methylethylphenoxy group, isopropylphenoxy group, butylphenoxy group, Examples include isobutylphenoxy, sec-butylphenoxy, tert-butylphenoxy, pentylphenoxy, isoamylphenoxy, hexylphenoxy, heptylphenoxy, octylphenoxy, nonylphenoxy, decylphenoxy, dodecylphenoxy It is done.

The arylalkoxy group as the substituent is a combination of the aryl group as the substituent and the alkoxy group as the substituent. The number of carbon atoms of the arylalkoxy group is usually 7 to 60, preferably 7 to 30. The aryl alkoxy group, a phenyl -C ₁ -C ₁₂ alkoxy group, C ₁ -C ₁₂ alkoxyphenyl -C ₁ -C ₁₂ alkoxy group, C ₁ -C ₁₂ alkylphenyl -C ₁ -C ₁₂ alkoxy group, 1 - naphthyl -C ₁ -C ₁₂ alkoxy groups, 2-naphthyl -C ₁ -C ₁₂ alkoxy groups and the like.

Examples of the substituted amino group as the substituent include an amino group substituted with one or more groups selected from the group consisting of an alkyl group, an aryl group, an arylalkyl group, and a monovalent heterocyclic group. The number of carbon atoms of the substituted amino group is usually 1 to 60, and preferably 2 to 48. Examples of the substituted amino group as a substituent include methylamino group, dimethylamino group, ethylamino group, diethylamino group, propylamino group, dipropylamino group, isopropylamino group, diisopropylamino group, butylamino group, isobutylamino group, sec-butylamino group, tert-butylamino group, pentylamino group, hexylamino group, cyclohexylamino group, heptylamino group, octylamino group, 2-ethylhexylamino group, nonylamino group, decylamino group, 3,7-dimethyloctyl Amino group, laurylamino group, cyclopentylamino group, dicyclopentylamino group, cyclohexylamino group, dicyclohexylamino group, pyrrolidyl group, piperidyl group, ditrifluoromethylamino group, phenylamino group, diphenyl Amino group, C ₁ -C ₁₂ alkoxyphenyl amino group, di (C ₁ -C ₁₂ alkoxyphenyl) amino group, di (C ₁ -C ₁₂ alkylphenyl) amino groups, 1-naphthylamino group, 2-naphthylamino group , pentafluorophenyl group, pyridylamino group, pyridazinylamino group, pyrimidylamino group, Pirajiruamino group, triazyl amino group, phenyl -C ₁ -C ₁₂ alkylamino group, C ₁ -C ₁₂ alkoxyphenyl -C ₁ ~ C ₁₂ alkylamino group, C ₁ -C ₁₂ alkylphenyl -C ₁ -C ₁₂ alkylamino group, di (C ₁ -C ₁₂ alkoxyphenyl -C ₁ -C ₁₂ alkyl) amino group, di (C ₁ -C ₁₂ alkylphenyl -C ₁ -C ₁₂ alkyl) amino groups, 1-naphthyl -C ₁ -C ₁₂ alkylamino group, 2-naphthyl -C ₁ -C ₁₂ alkylamino Etc. The.

  The number of carbon atoms of the acyl group as the substituent is usually 2 to 20, and preferably 2 to 18. Examples of the acyl group as a substituent include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pivaloyl group, a benzoyl group, a trifluoroacetyl group, and a pentafluorobenzoyl group.

  The number of carbon atoms of the acyloxy group as the substituent is usually 2 to 20, and preferably 2 to 18. Examples of the acyloxy group as a substituent include an acetoxy group, a propionyloxy group, a butyryloxy group, an isobutyryloxy group, a pivaloyloxy group, a benzoyloxy group, a trifluoroacetyloxy group, and a pentafluorobenzoyloxy group.

In the formula (1), R ¹ is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, an arylalkenyl group or an arylalkynyl group, more preferably an alkyl group, It is an alkenyl group, an aryl group, an arylalkyl group or an arylalkenyl group, more preferably an alkyl group, an alkenyl group or an arylalkyl group, and particularly preferably an alkyl group.

In the formula (1), R ² is the same as the group represented by R ¹ , but preferably a hydrogen atom, alkyl group, alkenyl group, aryl group, arylalkyl group, arylalkenyl group or arylalkynyl. More preferably a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an arylalkyl group or an arylalkenyl group, still more preferably a hydrogen atom, an alkyl group, an alkenyl group or an arylalkyl group, particularly Preferably, it is a hydrogen atom or an alkyl group.

  Examples of the compound represented by the formula (1) include the following formulas a-1 to a-11, b-1 to b-12, c-1 to c-7, d-1 to d-7, and The compounds represented by e-1 to e-12 are mentioned, and the synthesis of the compound becomes easier, so that in the following formulas a-1 to a-11, b-1 to b-12 and d-7 Compounds represented by the following formulas a-1 to a-11 and b-1 to b-12 are more preferable, and the following formulas a-3 to a-10 and b-3 to b are preferred. The compound represented by −10 is more preferable.

  In the production method of the present invention, the compound represented by the formula (1) may be used alone or in combination of two or more.

The metal salt is usually represented by the following formula (2).
M ^{m +} _a X ′ ⁿ⁻ _b (2)
(In the formula, M ^{m +} represents a metal ion having a positive charge. X ′ ⁿ⁻ represents an anion. A and b each independently represent an integer of 1 or more. When there are a plurality of M ^{m +} They may be the same or different, and when a plurality of X ′ are present, they may be the same or different.)

  In the formula (2), a is usually an integer of 1 to 3, preferably 1 or 2. b is usually an integer of 1 to 3, preferably 1 or 2. However, a and b are combinations in which there is no bias in the charge of the compound represented by the formula (2) as a whole.

In the formula (2), M represents a metal species, and m represents an integer of 1 or more.
Examples of the metal ion having a positive charge represented by M ^{m +} include ions of silver, gold, platinum, palladium, rhodium, iridium, ruthenium, osmium, iron, cobalt, copper, lead, tin, and the like. Silver ions, gold ions, platinum ions and copper ions are preferred, silver ions, gold ions and copper ions are more preferred, and silver ions are still more preferred.

In the formula (2), n represents an integer of 1 or more.
Examples of the anion represented by X ′ ⁿ⁻ include F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , OH ⁻ , CN ⁻ , NO ₃ ⁻ , NO ₂ ⁻ , ClO ⁻ , ClO ₂ ⁻ and ClO ₃ ^−. , ClO ₄ ⁻ , HSO ₄ ⁻ , SCN ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , R ³ O ⁻ (wherein R ³ represents a substituted or unsubstituted monovalent hydrocarbon group), R ⁴ COO ^- (wherein, R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group.), R ⁵ SO ₃ ^- (wherein, R ⁵ represents a monovalent hydrocarbon group substituted or unsubstituted. ), R ⁶ OCO ₂ ⁻ (wherein R ⁶ represents a substituted or unsubstituted monovalent hydrocarbon group), CO ₃ ²⁻ , S ²⁻ , SO ₄ ²⁻ , PO ₄ ³⁻ , O ^{2- and the} like, preferably Cl ⁻ , Br ⁻ , I ⁻ , NO ₃ ⁻ , ClO ⁻ , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , R ³ O ⁻ , R ⁴ COO ⁻ , R ⁵ SO ₃ ^-, R ⁶ CO _{3 ^{-, CO 3 2-, PO 4}} 3-, SO 4 2- , and the _{^{like, Cl -, NO 3 -,}} ClO 4 -, R 4 COO -, R 5 SO 3 -, R 6 CO 3 -, CO ₃ ²⁻ , PO ₄ ³⁻ and SO ₄ ²⁻ are preferred, and Cl ⁻ , NO ₃ ⁻ , ClO ₄ ⁻ , R ⁴ COO ⁻ , CO ₃ ²⁻ and SO ₄ ²⁻ are more preferred.

The monovalent hydrocarbon group represented by R ³ , R ⁴ , R ⁵ and R ⁶ (hereinafter referred to as “R ^{3 to} R ⁶ ”) is the monovalent hydrocarbon group described in R ^1. The definitions, specific examples, and preferred examples are the same as those described above.

  The said metal salt may use only 1 type, or may use 2 or more types together.

  The metal salt represented by the formula (2) is preferably a silver salt, and as the silver salt, silver chloride, silver bromide, silver iodide, silver sulfide, silver oxide, silver nitrate, silver hypochlorite, Examples include silver chlorite, silver chlorate, silver perchlorate, silver acetate, silver sulfate, silver carbonate, silver phosphate, silver tetrafluoroborate, silver hexafluorophosphate, and silver trifluoromethanesulfonate. Since the solubility of silver salts in solvents such as alcohol-based reducing solvents is good, silver nitrate, silver perchlorate, silver acetate, silver sulfate, silver carbonate, silver phosphate, silver tetrafluoroborate, hexafluorophosphorus Silver nitrate and silver trifluoromethanesulfonate are preferred, silver nitrate, silver perchlorate, silver acetate, silver carbonate, silver tetrafluoroborate, silver hexafluorophosphate and silver trifluoromethanesulfonate are more preferred, silver nitrate, acetic acid And more preferably silver carbonate, silver nitrate is particularly preferable.

  In the production method of the present invention, the amount of the compound represented by the formula (1) is usually 1 to 0.0001 mol, preferably 0.1 to 0.0001, relative to 1 mol of the metal salt. More preferably, it is 0.05-0.0001 mol, More preferably, it is 0.05-0.001 mol, Most preferably, it is 0.01-0.001 mol.

  Examples of the polar polymer include polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyethyleneimine, starch, gelatin, carboxymethylcellulose, methylcellulose, polyvinyl alcohol, polyethylene oxide and derivatives thereof, preferably polyvinyl Pyrrolidone, polyacrylic acid, polyacrylamide, polyethyleneimine, polyvinylpyrrolidone and polyethylene oxide, more preferably polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyethyleneimine and polyethylene oxide, particularly preferably polyvinylpyrrolidone, Acrylic acid, polyacrylamide and polyethyleneimine.

The weight average molecular weight in terms of polystyrene of the polar polymer is usually 3 × 10 ² to 1 × 10 ⁶ , preferably 5 × 10 ² , since the solubility in a solvent such as an alcohol-based reducing solvent described later is good. a to 3 × 10 ^5, more preferably from ^{1 × 10 3 ~1 × 10 5} , particularly preferably from ^{3 × 10 3 ~1 × 10 5} .

  In the production method of the present invention, the addition amount of the polar polymer is usually 0.001 to 1000 mol, preferably 0.01 to 100 mol, more preferably 0.001 mol, per 1 mol of the metal salt. 1 to 10 mol, particularly preferably 1 to 5 mol. This is because metal nanowires having a more preferable aspect ratio can be obtained more easily.

  In the production method of the present invention, the polar polymers may be used singly or in combination of two or more.

  Examples of the reducing agent include hydrazine, sodium borohydride, citric acid, oxalic acid, hydrogen gas, 1,2-ethanediol (hereinafter sometimes referred to as “ethylene glycol”), 1,2-propanediol. 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, pentanediol, hexanediol, heptanediol, octanediol, diethylene glycol, Triethylene glycol, tetraethylene glycol, dipropylene glycol, hexylene glycol, 2-butene-1,4-diol, glycerol, 1,1,1-trishydroxymethylethane, 2-ethyl-2-hydroxymethyl-1, 3-propanediol, 1,2,3-hex And alcohol-based reducing solvents such as Ntriol and benzyl alcohol, preferably the above-mentioned alcohol-based reducing solvents, more preferably 1,2-ethanediol (ethylene glycol), 1,2-propanediol, 1 , 3-propanediol.

  In the manufacturing method of this invention, the said reducing agent may be used individually by 1 type, or may use 2 or more types together.

  In the production method of the present invention, the amount of the reducing agent added may be more than the amount necessary for reducing the metal salt. When the reducing agent is a reducing agent other than the alcohol-based reducing solvent, it is usually at least 0.1 mole, preferably at least 1 mole relative to 1 mole of the metal salt. When the reducing agent is an alcohol reducing solvent, the upper limit addition amount is usually 100 L, preferably 60 L, more preferably 40 L, particularly preferably 30 L with respect to 1 mol of the metal salt. The addition amount is usually 10 mL with respect to 1 mol of the metal salt.

  In the production method of the present invention, a solvent other than the alcohol-based reducing solvent (for example, hydrogen halide) may be further added.

  Examples of the hydrogen halide include hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, and the like, and hydrogen chloride is preferred because of its good affinity with the metal salt.

  Examples of the solvent other than the alcohol-based reducing solvent different from hydrogen halide include benzene, toluene, xylene, orthodichlorobenzene, chloroform, tetrahydrofuran, hexane, diethyl ether, acetonitrile, N-methylpyrrolidone, and the like. It is done.

  The reaction temperature in the manufacturing method of this invention is 40-200 degreeC normally, Preferably it is 60-190 degreeC, More preferably, it is 100-190 degreeC, More preferably, it is 110-170 degreeC.

  The reaction time in the production method of the present invention is usually 5 minutes or more, preferably 10 minutes or more, more preferably 20 minutes or more, and particularly preferably 30 minutes or more. However, the upper limit reaction time is usually 300 minutes. It is because the yield of the obtained metal nanowire tends to be better when the reaction time is 30 to 300 minutes.

  In the production method of the present invention, when a solvent other than the alcohol-based reducing solvent is used, the amount of the solvent is preferably 1 mL or more, more preferably 10 mL or more, further preferably 50 mL or more with respect to 1 mol of the metal salt. 150 mL or more is particularly preferable, and 200 mL or more is particularly preferable. This is because when the amount of the solvent is within these ranges, the metal salt is easily dissolved, and a large amount of metal nanowires can be produced at one time.

  In the production method of the present invention, the metal salt, the reducing agent, the polar polymer, and the compound represented by the formula (1) (hereinafter, these may be referred to as “raw materials”) may be reacted in any order. Good. For example, the raw materials may be reacted all at once, a part of the raw materials may be reacted first, and the remaining raw materials may be reacted after a certain time has elapsed.

  In the production method of the present invention, the raw material may be reacted by any method, for example, a part or all of the raw material may be dissolved in a solvent and then reacted in a reaction vessel. After the addition, a solvent may be added and dissolved to react. In addition, when the solubility of a polar polymer is low, it is preferable to make it react with a metal salt after dissolving a polar polymer in a solvent.

  In the production method of the present invention, heating is usually performed in order to obtain the reaction temperature. However, the heating may be performed after mixing all of the raw materials or after mixing a part of the raw materials. May be. In addition, you may heat previously things (for example, said solvent) other than a raw material.

  The production method of the present invention may include a purification step for purifying the product to obtain high-purity metal nanowires after the above reaction. This purification step can be performed by centrifugation, supernatant removal, redispersion, filtration, ultrafiltration, washing, heating, drying, and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited at all by these.

<Example 1>
In a 500 mL flask, 2.08 g (18.75 mmol) of polyvinylpyrrolidone (hereinafter referred to as “PVP”) (polystyrene equivalent weight average molecular weight: 5.5 × 10 ⁴ ), 21.8 mg (0.125 mmol) 1-Butyl-3-methylimidazolium chloride and 200 mL of ethylene glycol were added and stirred until the PVP was dissolved. 2.12 g (12.50 mmol) of silver nitrate was added to the obtained solution, and the silver nitrate adhering to the wall surface of the flask was dissolved with 50 mL of ethylene glycol and poured into the flask. Next, the flask was immersed in an oil bath at 165 ° C. and stirred for 120 minutes to obtain a silver nanowire dispersion. After cooling the obtained dispersion to room temperature, the solvent was dried, and the obtained silver nanowire was SEM (manufactured by JEOL Ltd., trade name: JSM-5500, the angle of the sample stage was 0 ° during observation) Horizontal), and the shooting location is an arbitrary location, and there is no operation to arrange at the time of sample preparation.) As a result of visual confirmation from the photograph of), among 100 randomly selected from unpurified silver nanowires Thus, there were 91 silver nanowires having a short axis (shortest diameter) of 1000 nm or less and an aspect ratio of 1.5 or more, and all were single silver nanowires.

<Example 2>
In Example 1, instead of using 21.8 mg (0.125 mmol) of 1-butyl-3-methylimidazolium chloride, 25.3 mg (0.125 mmol) of 1-hexyl-3-methylimidazolium chloride A silver nanowire was obtained in the same manner as in Example 1 except that was used. When silver nanowires were confirmed in the same manner as in Example 1, among 100 randomly selected from unpurified silver nanowires, the short axis (shortest diameter) was 1000 nm or less, and the aspect ratio There were 95 silver nanowires having a ratio of 1.5 or more, and all were single silver nanowires.

<Example 3>
In a 50 mL flask, 125 mg (11.25 mmol) of PVP (polystyrene equivalent weight average molecular weight: 5.5 × 10 ⁴ ), 1.3 mg (0.0075 mmol) of 1-butylimidazolium chloride and 10 mL of ethylene glycol were added. In addition, stirring was performed until the PVP was dissolved. Next, 127 mg (7.50 mmol) of silver nitrate was added thereto, and silver nitrate adhering to the wall of the flask was poured into the flask with 5 mL of ethylene glycol. Next, the flask was immersed in an oil bath at 160 ° C. and stirred for 90 minutes, whereby a silver nanowire dispersion liquid was obtained. When silver nanowires were confirmed in the same manner as in Example 1, among 100 randomly selected from unpurified silver nanowires, the short axis (shortest diameter) was 1000 nm or less, and the aspect ratio There were 96 silver nanowires having a ratio of 1.5 or more, and all were single silver nanowires.

<Example 4>
In a 500 mL flask, 4.17 g (37.5 mmol) of PVP (polystyrene equivalent weight average molecular weight: 5.5 × 10 ⁴ ), 54.2 mg (0.25 mmol) of 1-hexyl 2,3-dimethylimidazolium chloride And 200 mL of ethylene glycol were added and stirred until the PVP was dissolved. Next, 4.25 g (25.0 mmol) of silver nitrate was added thereto, and silver nitrate adhering to the wall surface of the flask was poured into the flask with 50 mL of ethylene glycol. Next, the flask was immersed in an oil bath at 150 ° C. and stirred for 40 minutes, whereby a silver nanowire dispersion liquid was obtained. When silver nanowires were confirmed in the same manner as in Example 1, among 100 randomly selected from unpurified silver nanowires, the short axis (shortest diameter) was 1000 nm or less, and the aspect ratio There were 50 silver nanowires having a ratio of 1.5 or more, and all were single silver nanowires.

<Comparative Example 1>
In Example 1, except that 1-butyl-3-methylimidazolium chloride was not used, a reaction was performed in the same manner as in Example 1, whereby a particulate silver nanomaterial was obtained. The silver nanomaterial was confirmed in the same manner as in Example 1, and among the 100 randomly selected from the unpurified silver nanomaterial, the definition of the present specification (the shortest diameter is 1000 nm or less, the wire shape The number of silver nanowires that satisfy the individual) was zero.

<Comparative Example 2>
In Example 1, instead of using 21.8 mg (0.125 mmol) of 1-butyl-3-methylimidazolium chloride, 31.3 mg (0.125 mmol) of 1-butyl-3-methylimidazolium methylsulfate A reaction was carried out in the same manner as in Example 1 except that the fate was used. As a result, a particulate silver nanomaterial was obtained. The silver nanomaterial was confirmed in the same manner as in Example 1, and among the 100 randomly selected from the unpurified silver nanomaterial, the definition of the present specification (the shortest diameter is 1000 nm or less, the wire shape The number of silver nanowires that satisfy the individual) was zero.

Claims (2)

Reducing agent, in the presence of a compound represented by polar polymer and the following formula (1), comprises reacting a gold Shokushio a method for producing a metal nanowires,
The manufacturing method of the said metal nanowire whose addition amount of the compound represented by the said Formula (1) is 0.001-0.01 mol with respect to 1 mol of said metal salts.

(Where
X ⁻ represents a halide ion.
R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and a plurality of R ² may be the same or different. ) The metal is silver in the metal salt and the metal nanowires, method of producing metal nanowires of claim 1.

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