JP2014047364A - Metal nanoparticle protective polymer, metal colloidal solution and manufacturing methods therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To intentionally add and adjust a plurality of properties, such as good metal nanoparticle control ability, high dispersion stability, good low-temperature firing property, and easy purification separation property of metal nanoparticles to make it more practical To provide a metal nanoparticle protective polymer capable of developing conductivity, a metal colloid solution, and a production method thereof.
SOLUTION: A metal nanoparticle having a polyalkyleneimine N-oxide segment (A) obtained by oxidizing a nitrogen atom in a polyalkyleneimine and a hydrophilic segment (B) in one molecule. Metal nanoparticles characterized by oxidizing precursor compound (I) having polyalkyleneimine segment (a) and hydrophilic segment (B) in one molecule using a protective polymer and oxidizing agent (II) A method for producing a protective polymer, a method for producing a metal colloid solution characterized by reducing metal ions in a medium to form metal nanoparticles in the presence of the protective polymer, and the obtained metal colloid solution.
[Selection figure] None

Description

  The present invention relates to a metal colloid solution using a polymer containing a polyalkyleneimine N-oxide segment and a hydrophilic segment, or a polymer further containing a hydrophobic segment as a protective agent for metal nanoparticles, a production method thereof, In addition, the present invention relates to the polymer and a production method thereof.

  Metal nanoparticles are nanoparticles having a particle size of 1 to several hundred nanometers, and their specific surface area is remarkably large, so they are attracting attention from many fields, and include electronic materials, catalysts, magnetic materials, optical materials, various sensors, colors Application to materials, medical examinations, etc. is expected.

  Although printed wiring boards and semiconductor devices are manufactured exclusively through a photolithographic process, they have complicated multi-stage manufacturing processes. Attention has been focused on the production technology of a coating type electronic device which is dispersed in the above to form an ink composition, which is patterned by various printing methods and assembled as a device.

  Such technology is called printed electronics, but this method has the possibility that electronic circuit patterns and semiconductor elements can be mass-produced by roll-to-roll, on-demand, simplification of processes and resource saving. Is expected to develop into a low-cost manufacturing method for display devices, light-emitting devices, IC tags (RFIDs), and the like. As the conductive material ink used in the printed electronics, a conductive ink composed of metal nanoparticles such as gold, silver, platinum, and copper can be used. However, silver is used because of economy and ease of handling. Nanoparticles and their inks have been developed in advance.

  When the metal of the silver nano particles is reduced to nano size, the specific surface area is remarkably higher than that of bulk silver and the surface energy is increased. Therefore, there is a strong tendency to fuse with each other to reduce the surface energy. As a result, the grains are fused together at a temperature much lower than the melting point of bulk silver. This is sometimes referred to as a quantum size effect (Kubo effect), which has the merit of using silver nanoparticles as a conductive material. However, the ease of fusion between the metal nanoparticles impairs the stabilization of the metal nanoparticles, and the storage stability deteriorates. To stabilize the metal nanoparticles, to prevent the fusion It is necessary to protect with a protective agent.

  In general, nanomaterials (general compounds having a size on the order of nanometers) tend to be expensive because they are manufactured through a special process because of their size, which is one factor that hinders their spread. . In order to produce metal nanoparticles at a low cost, a liquid phase reduction method that does not require a special apparatus such as a vacuum process is advantageous. The liquid phase reduction method is a method in which a metal compound is reacted with a reducing agent in a solvent and reduced to obtain metal nanoparticles. At that time, the shape and particle size of the generated metal nanoparticles are controlled and stable. In order to form a dispersion state, a technique for performing reduction in the presence of a compound also called a dispersion stabilizer or a protective agent is disclosed. The protective agent is exclusively designed to have functional groups that can coordinate to metal particles such as tertiary amino groups, quaternary ammonium groups, heterocyclic rings with basic nitrogen atoms, hydroxy groups, carboxyl groups, etc. In many cases, it is a polymer compound prepared (see, for example, Patent Document 1).

As described above, in order to produce metal nanoparticles that are expected to have a good low-temperature fusion phenomenon, it is necessary to use a protective agent that can appropriately control the shape and particle size of the metal nanoparticles, obtain dispersion stability, and the like. Become. However, since the protective agent reduces the conductive performance as a resistance component for the fused bulk metal, depending on the amount used, good low-temperature sinterability (100-150 ° C thin film coated with metal nanoparticle-containing conductive ink) The specific resistance obtained by baking with a characteristic of ^10-6 Ωcm order becomes difficult to express. Thus, from the viewpoint of the design of the conductive material, the protective agent has the ability to produce particles in a small size, and the ability to stably disperse the particles. From the viewpoint of producing metal nanoparticles, it is necessary to simultaneously have a plurality of properties such as the ability to easily purify and separate the produced metal nanoparticles. It can be used as such a protective agent, such as commercially available polymer pigment dispersants such as Solsperse (trademark of Zeneca) and Florene (trademark of Kyoeisha Chemical Co., Ltd.), and a pigment affinity group (amine) as a main chain / side chain. However, it is difficult to realize these simultaneously by using only a polymer having a plurality of solvation moieties and a copolymer polymer having a polyethyleneimine moiety and a polyethylene oxide moiety. Therefore, further improvement is necessary (see, for example, Patent Documents 2 to 4).

JP 2004-346429 A JP-A-11-080647 JP 2006-328472 A JP 2008-037884 A

  The problem to be solved by the present invention is to intentionally add and adjust multiple properties such as good controllability of metal nanoparticles, high dispersion stability, good low-temperature calcinability, and easy purification separation of metal nanoparticles. Thus, it is an object of the present invention to provide a metal nanoparticle protective polymer, a metal colloid solution, and a method for producing them that can exhibit more practical conductivity.

  The inventor of the present invention provides a binary polymer in which a polyalkyleneimine segment containing polyethyleneimine and a hydrophilic segment containing a polyoxyalkylene chain are bonded, or a hydrophobic segment such as an epoxy resin is further added to the binary system. It has already been disclosed that the bonded ternary polymer is effective for the production of metal nanoparticles (Patent Document 4, etc.). However, with this technology, since the above-mentioned performance could not be achieved at a high level, as a result of further intensive studies, a polymer obtained by oxidizing the nitrogen atom in the polyalkyleneimine segment was used. Has been found to be effective, and the present invention has been completed.

  That is, the present invention is a metal having a polyalkyleneimine N-oxide segment (A) obtained by oxidizing a nitrogen atom in a polyalkyleneimine and a hydrophilic segment (B) in one molecule. The present invention provides a nanoparticle protective polymer, a production method thereof, a metal colloid solution in which a metal nanoparticle-containing complex using this as a protective agent is dispersed in a medium, and a production method thereof.

  The metal colloid solution obtained by the present invention exhibits good low-temperature firing properties. Such good conductive performance at low temperature is due to the fact that the protective polymer used in the present invention is easily detached from the surface of the metal nanoparticles at low temperature. In addition, the metal nanoparticles obtained in the presence of this specific protective polymer have a sufficiently small particle size, a monodispersed particle size and a narrow particle size distribution, and exhibit good storage stability. This protects the metal nanoparticles by the high coordination binding force of the N-oxide structure portion to the metal in the protective polymer and also exhibits the dispersibility in the medium by the hydrophilic segment or the hydrophobic segment in the polymer. Thus, the dispersion stability as a dispersion is not impaired, and a stable dispersion state is maintained for a long time in a solvent.

  In the present invention, when producing a metal colloid solution, after the metal nanoparticles are obtained by reduction, in the purification separation method step of removing impurities, the produced dispersion of the composite composed of the metal nanoparticles and the protective polymer is used. The complex easily settles and separates only by a simple operation of adding a poor solvent, but this is due to the strong associating force of the protective polymer, and it requires almost no complicated process or precise condition setting. It is highly advantageous as a general manufacturing method.

  Further, the metal nanoparticles in the metal colloid solution obtained by the present invention have characteristics as metal nanoparticles such as a large specific surface area, high surface energy, and plasmon absorption, and further, dispersion stability possessed by the self-organized polymer dispersion. Properties, storage stability, etc. can be efficiently expressed, and has various chemical, electrical, and magnetic performances required as conductive pastes, etc., in various fields such as catalysts, electronic materials, magnetic materials, Applications to optical materials, various sensors, color materials, medical examinations, etc. are possible.

  The metal nanoparticle protective polymer of the present invention includes a polymer compound having a polyalkyleneimine N-oxide segment (A) and a hydrophilic segment (B), or a polyalkyleneimine N-oxide segment (A) and a hydrophilic property. A polymer compound having a segment (B) and a hydrophobic segment (C). Dispersion of metal nanoparticles (metal colloid solution) protected by a protective polymer having such a structure is excellent in dispersion stability and conductive properties, and has various color development, catalyst, electrical function, etc. possessed by metal nanoparticles. As a metal-containing functional dispersion.

  The polyalkyleneimine N-oxide segment (A) in the protective polymer in the present invention is fixed as a nanoparticle because the alkyleneimine N-oxide unit in the segment can be coordinated with the metal or metal ion. It is a segment that can be converted. In the case where a complex formed by protecting the metal nanoparticles obtained in the present invention with the protective polymer is produced or stored in a hydrophilic solvent, a polyalkyleneimine N-oxide segment (A ) And the hydrophilic segment (B), the obtained metal colloid solution can exhibit particularly excellent dispersion stability and storage stability.

  From the viewpoint of an industrial production method, a simple purification / separation method of a complex formed by dissolving or dispersing a metal compound in a medium and reducing the resulting metal nanoparticles with the protective polymer is important. It is preferable to adopt a method in which a poor solvent such as acetone is added to the solution after the reaction to separate by precipitation. The alkyleneimine N-oxide unit of the protective polymer of the present invention has a function of promptly advancing the association between the metal nanoparticle-containing complexes in a poor solvent environment from a high polarity, making it easy to create a block of a large association group To settle.

  In addition, the metal colloid solution itself, which is a dispersion of the metal nanoparticle-containing composite, or a conductive material prepared by adjusting this solution to a conductive ink is protected during the sintering process after printing or coating on a substrate. Like the quaternary amine, the alkyleneimine N-oxide unit in the polymer has a weak binding force, so it can be easily decaptured from the metal nanoparticle surface even at a low temperature. It shows sex.

  The particle size of the dispersion (composite) in the metal colloid solution of the present invention is not limited to the molecular weight of the protective polymer used and the degree of polymerization of the polyalkyleneimine N-oxide segment (A), but also the components constituting the protective polymer, That is, it is also affected by the structure and composition ratio of the polyalkyleneimine N-oxide chain (A), the hydrophilic segment (B) described later, and the hydrophobic segment (C) described later.

  The degree of polymerization of the polyalkyleneimine N-oxide segment (A) is not particularly limited, but if it is too low, the protective ability of the metal nanoparticles as a protective polymer may be insufficient and too high. The particle diameter of the composite particles composed of the metal nanoparticles and the protective polymer may become large, which may hinder storage stability. Therefore, in order to improve the ability to immobilize metal nanoparticles and the ability to prevent the dispersion particles from becoming enormous, the number of alkyleneimine units of the polyalkyleneimine N-oxide segment (A) (polymerization) Degree) is usually in the range of 1 to 10,000, preferably in the range of 5 to 2,500, and most preferably in the range of 5 to 300.

  The polyalkyleneimine N-oxide segment (A) can be easily obtained by oxidizing the alkyleneimine moiety in the polyalkyleneimine segment, which is the precursor structure, and specifically obtained by contact with an oxidizing agent. be able to. The segment composed of the polyalkyleneimine can be used without particular limitation as long as it is generally commercially available or can be synthesized, but from the viewpoint of industrial availability, branched polyethyleneimine, A branched polypropyleneimine is preferable, and a branched polyethyleneimine is particularly preferable.

  When the hydrophilic segment (B) constituting the protective polymer of the present invention uses a hydrophilic medium such as water as the metal colloid solution, the hydrophilic segment (B) has a high affinity with a solvent, and the storage stability of the colloidal solution. It is a segment that retains sex. Moreover, when using a hydrophobic solvent, it has the role which forms the core of a dispersion particle by the strong association force in the molecule | numerator of this hydrophilic segment (B) or between molecules. The degree of polymerization of the hydrophilic segment (A) is not particularly limited. However, when a hydrophilic solvent is used, storage stability may be deteriorated if the degree of polymerization is too low, and aggregation may occur if the degree is too high. In the case of using a hydrophobic solvent, if the degree of polymerization is too low, the associating power of the dispersion particles becomes poor, and if it is too high, the affinity with the solvent cannot be maintained. From these viewpoints, the degree of polymerization of the hydrophilic segment (B) is usually 1 to 10,000, preferably 3 to 3,000, and 5 to 1,000 from the viewpoint of ease of production. It is more preferable that Furthermore, the polymerization degree when the hydrophilic segment is a polyoxyalkylene chain is particularly preferably 5 to 500.

  The hydrophilic segment (B) can be used without particular limitation as long as it is generally composed of a commercially available or synthesizable hydrophilic polymer chain. In particular, when a hydrophilic solvent is used, it is preferably made of a nonionic polymer because a colloid solution having excellent stability can be obtained.

  Examples of the hydrophilic segment (B) include polyoxyalkylene chains such as polyoxyethylene chains and polyoxypropylene chains, polymer chains composed of polyvinyl alcohols such as polyvinyl alcohol and partially saponified polyvinyl alcohol, polyhydroxyethyl acrylate, poly Polymer chains composed of water-soluble poly (meth) acrylic esters such as hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, polyacetylethyleneimine, polyacetylpropyleneimine, polypropionylethyleneimine, polypropionylpropyleneimine Polyacylalkyleneimine chains having hydrophilic substituents such as polyacrylamide, polyisopropylacrylamide, polyvinyl pyrrolidone, etc. Polymer chains composed of acrylamides can be exemplified, and among these, a colloid solution having particularly excellent stability is obtained, and a polyoxyalkylene chain is preferred from the viewpoint of easy industrial availability. .

  In the present invention, the protective polymer may further have a hydrophobic segment (C). In particular, when the medium is an organic solvent as a metal colloid solution, it is preferable to use a polymer having a hydrophobic segment (C) as a protective agent.

  The hydrophobic segment (c) can be used without particular limitation as long as it is composed of residues of hydrophobic compounds that are generally commercially available or can be synthesized. For example, polystyrenes such as polystyrene, polymethylstyrene, polychloromethylstyrene, polybromomethylstyrene, polyacrylic acid methyl ester, polymethacrylic acid methyl ester, polyacrylic acid 2-ethylhexyl ester, polymethacrylic acid 2-ethylhexyl ester, etc. Water-insoluble poly (meth) acrylic acid esters, polybenzoylethyleneimine, polybenzoylpropyleneimine, poly (meth) acryloylethyleneimine, poly (meth) acryloylpropyleneimine, poly [N- {3- (perfluoro Octyl) propionyl} ethyleneimine], poly [N- {3- (perfluorooctyl) propionyl} propyleneimine] and the like polymer residues of polyacylalkyleneimines having a hydrophobic substituent, Epoxy resins, polyurethanes, include such residues of the resin and polycarbonate, also a residue of a single compound or a residue of a compound obtained by previously reacting the two or more different compounds. Among these, from the viewpoint that the synthesis of the protective polymer is industrially easy, and from the viewpoint of excellent adhesion to the base material when printing and applying the obtained metal colloid solution, it is composed of a structure derived from an epoxy resin. In particular, the hydrophobic segment (C) having a structure derived from a bisphenol A type epoxy resin is preferable.

  In addition, the degree of polymerization of the hydrophobic segment (C) is not particularly limited, but is usually 1 to 10,000, and polystyrenes, poly (meth) acrylic acid esters, poly having a hydrophobic substituent. In the case of acylalkylenimines and the like, it is preferably from 3 to 3,000, more preferably from 10 to 1,000. Moreover, when it consists of resin residues, such as an epoxy resin, polyurethanes, and polycarbonates, the polymerization degree is usually 1 to 50, preferably 1 to 30, particularly 1 to 20. preferable.

  The method for producing a metal nanoparticle protective polymer of the present invention includes a compound having a polyalkyleneimine segment and a hydrophilic segment (B) as the precursor compound (I), or a polyalkyleneimine segment and a hydrophilic segment (B). And a compound having a hydrophobic segment (C), and this is treated with an oxidizing agent. By using such a method, a protective polymer as designed can be easily obtained. About the manufacturing method of precursor compound (I), the method described in the said patent document 4 and Unexamined-Japanese-Patent No. 2006-213887 can be used as it is.

  After obtaining such precursor compound (I), the nitrogen atom in the polyalkyleneimine segment contained therein is oxidized. Oxidation is carried out by using a compound having a peroxide structure (—O—O—, —N—O—) in the aqueous solution of the precursor compound (I), such as hydrogen peroxide, metal peroxide, inorganic peracid and its salt, organic This is done by adding peroxides such as peroxy compounds and organic peracids and salts thereof.

  As the hydrogen peroxide, what is industrially supplied as 30-50% hydrogen peroxide water can be used. As examples of metal peroxides, sodium peroxide, potassium peroxide, lithium peroxide, magnesium peroxide, zinc peroxide and the like are easily available and can be used similarly. Examples of inorganic peracids and salts thereof include persulfuric acid, percarbonate, perphosphoric acid, hypoperchloric acid, oxone (a registered trademark of DuPont, an oxidizing agent mainly composed of potassium hydrogen persulfate), ammonium persulfate, and sodium persulfate. , Potassium persulfate, sodium percarbonate and the like can be used. Organic peroxy compounds and organic peracids and their salts include peracetic acid, perbenzoic acid, m-chlorobenzoic acid, benzoyl peroxide, t-butyl peroxide, 1,2-dimethyldioxirane, Davis reagent (2- (phenylsulfonyl) ) -3-aryloxaziridine) and the like, and these can also be used. Among these oxidizing agents, particularly preferably used are 30% aqueous hydrogen peroxide, ammonium persulfate, oxone, and peracetic acid, which are easy to obtain and handle and inexpensive.

  The oxidizing agents listed above can give one oxygen atom per nitrogen atom. A one-to-one reaction may be assumed for the tertiary and secondary amines. The reaction with the primary amine is assumed to be complicated, and it is not limited to the reaction with one molecule of the oxidant, and the reaction with the next oxidant can be considered. With this in mind, as a result of examining the amount of the oxidizing agent, the oxidizing agent corresponding to 10.5 to 100% of the total number of nitrogen atoms in the polyalkyleneimine segment in the precursor compound (I) It has been found that a protective polymer exhibiting good conductivity, dispersion stability and easy purification separation can be obtained when the is added.

In particular, when the polyalkyleneimine segment is based on a branched polyalkyleneimine compound, primary, secondary and tertiary amines are uniformly and randomly contained, and an oxidizing agent is added to these. When reacted, the tertiary amine is only amine oxide (C—N ⁺ (O ⁻ ) (— C) —C), and the secondary amine is amine oxide (C—HN ⁺ (O ⁻ ) —C). ) And the reaction conditions, hydroxylamine (CN (OH) -C) and its oxidized nitrone (C = CN ⁺ (O ^- ) ^- C) are converted into primary amines. From hydroxylamine (C—NH (OH)), nitroso (C—NO), and nitro (C—NO ₂ ), it is estimated that the resulting protected polymer may contain a small amount of the above structure. . Although such a complicated oxidation state has a considerable influence on the protective ability of the resulting protective polymer, it is not necessary to consider a mixed state and make a single structure. It is preferable that the branched polyalkyleneimine segment that can be mixed is oxidized from the viewpoint of the storage stability of the resulting metal colloid solution and the low-temperature sinterability of the coating film obtained by using this. is there.

  The metal nanoparticle protective polymer of the present invention has a hydrophilic segment (B) or further a hydrophobic segment (C) separately from the polyalkyleneimine N-oxide segment (A) capable of stably presenting metal nanoparticles. Have As described above, the hydrophilic segment (B) shows a strong associating force in a hydrophobic solvent, shows a high affinity with the solvent in the hydrophilic solvent, and the hydrophobic segment (C) in the hydrophilic solvent. It exhibits a strong associative force and exhibits a high affinity with a solvent in a hydrophobic solvent. Furthermore, in the case where the hydrophobic segment (C) has an aromatic ring, it is considered that π electrons of the aromatic ring interact with the metal, thereby further contributing to stabilization of the metal nanoparticles. .

  The molar ratio (A) :( B) of the polymer constituting the chain of each component of the polyalkyleneimine N-oxide segment (A) and the hydrophilic segment (B) in the metal nanoparticle protective polymer of the present invention is particularly limited. Although it is not carried out, it is usually in the range of 1: (1 to 100), particularly preferably 1: (1 to 30), from the viewpoint of excellent dispersion stability and storage stability of the resulting colloidal solution. In the case of a polymer also having a hydrophobic segment (C), the moles of the polymer constituting the chain of each component of the polyalkyleneimine N-oxide segment (A), the hydrophilic segment (B), and the hydrophobic segment (C) The ratio (A) :( B) :( C) is not particularly limited, but is usually 1: (1 to 100) :() from the viewpoint of excellent dispersion stability and storage stability of the resulting colloidal solution. 1 to 100), and 1: (1-30) :( 1-30) is particularly preferable. From the above, the weight average molecular weight of the metal nanoparticle protective polymer of the present invention is preferably in the range of 1,000 to 500,000, particularly preferably in the range of 1,000 to 100,000.

  The protective polymer of the present invention is dispersed or dissolved in various media and used for the production of a metal colloid solution. What can be used as the medium is not limited, and the dispersion may be either an O / W system or a W / O system. Depending on the production method of the metal colloid solution and the intended use of the resulting metal colloid solution, various hydrophilic solvents, hydrophobic solvents, or mixed solvents thereof, or mixed solvents that use other solvents as described later can be selected. Can be used. When a mixed solvent is used, the hydrophilic solvent is increased when the mixing ratio is O / W, and the hydrophobic solvent is increased when W / O. Since the mixing ratio varies depending on the type used, it cannot be generally limited. However, as a general guideline, when an O / W system is used, a hydrophilic solvent having a capacity of 5 times or more that of a hydrophobic solvent is used. In the case of the / O system, it is preferable to use a hydrophobic solvent having a capacity 5 times or more that of the hydrophilic solvent.

  Examples of the hydrophilic solvent include methanol, ethanol, isopropyl alcohol, tetrahydrofuran, acetone, dimethylacetamide, dimethylformamide, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, dimethyl Examples thereof include sulfone oxide, dioxirane, N-methylpyrrolidone and the like, and they may be used alone or in admixture of two or more.

  Examples of the hydrophobic solvent include hexane, cyclohexane, ethyl acetate, butanol, methylene chloride, chloroform, chlorobenzene, nitrobenzene, methoxybenzene, toluene, xylene, and the like. good.

  Examples of other solvents that can be used by mixing with a hydrophilic solvent or a hydrophobic solvent include ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and the like. It is done.

  The method for dispersing the metal nanoparticle protective polymer in the medium is not particularly limited, and can be easily obtained by standing or stirring at room temperature, but may be ultrasonicated if necessary. Further, a heat treatment or the like may be performed. When the familiarity with the medium is low due to the crystallinity of the protective polymer, etc., for example, the protective polymer may be dissolved or swollen with a small amount of a good solvent and then dispersed in the target medium. At this time, it is more effective to perform ultrasonic treatment or overheat treatment.

  When a hydrophilic solvent and a hydrophobic solvent are mixed and used, the mixing method and mixing order are not particularly limited, and various methods may be used. Since the affinity and dispersibility with various solvents may vary depending on the type and composition of the protective polymer used, the solvent mixing ratio, mixing order, mixing method, mixing conditions, etc. are appropriately selected according to the purpose. It is preferable.

  The method for producing a metal colloid solution of the present invention is to reduce metal ions into metal nanoparticles in the above-mentioned protective polymer solution or dispersion, and the source of metal ions is a metal salt or metal An ionic solution of The source of the metal ion may be any water-soluble metal compound, such as a salt of a metal cation and an acid group anion, or one in which the metal is contained in an anion of an acid group, a transition metal, etc. Metal ions having the following metal species can be preferably used.

As a transition metal ion, even if it is a transition metal cation (M ^{n +} ) or an anion (ML _x ⁿ⁻ ) composed of a halogen bond, it can be suitably coordinated in a complex state. . In addition, in this specification, a transition metal refers to the transition metal element which exists in 4th-6th period in 4th-12th group of a periodic table.

Examples of transition metal cations include the following transition metal cations (M ^{n +} ), such as monovalent, divalent, trivalent, or tetravalent cations such as Cr, Co, Ni, Cu, Pd, Ag, Pt, and Au. Is mentioned. The counter anion of these metal cations may be Cl, NO ₃ , SO ₄ , or an organic anion of carboxylic acids.

Further, anions containing the following metals (ML _x ⁿ⁻ ), such as AgNO ₃ , AuCl ₄ , PtCl ₄ , and CuF ₆ , are also preferably coordinated in a complex state. Can be made.

  Among these metal ions, silver, gold, and platinum metal ions are particularly preferable because they are reduced spontaneously at room temperature or in a heated state and converted into nonionic metal nanoparticles. Moreover, when using the obtained metal colloid solution as a conductive material, it is preferable to use silver ion from the viewpoint of the ability to develop conductivity and the antioxidant properties of a film obtained by printing and painting.

  Moreover, it is also possible to make 2 or more types of metal species to contain. In this case, since various metal ions undergo reduction reactions in the medium by adding various metal salts or ions simultaneously or separately, and various metal particles are generated, a colloidal solution containing various metals. Can be obtained.

  In the present invention, the metal ion may be further reduced by a reducing agent.

  Various reducing agents can be used as the reducing agent, and are not particularly limited. It is preferable to select the reducing agent according to the intended use of the resulting metal colloid solution, the metal species to be contained, and the like. Examples of reducing agents that can be used include boron compounds such as hydrogen, sodium borohydride, ammonium borohydride, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, ethylene glycol, and propylene glycol, formaldehyde, acetaldehyde, Aldehydes such as propionaldehyde, acids such as ascorbic acid, citric acid, sodium citrate, propylamine, butylamine, diethylamine, dipropylamine, dimethylethylamine, triethylamine, ethylenediamine, triethylenetetramine, methylaminoethanol, dimethylaminoethanol, Examples include amines such as triethanolamine, and hydrazines such as hydrazine and hydrazine carbonate. Among these, sodium borohydride, ascorbic acid, sodium citrate, methylaminoethanol, dimethylaminoethanol and the like are more preferable from the viewpoint of industrial availability and handling.

  In the method for producing a metal colloid solution of the present invention, the use ratio of the protective polymer and the source of metal ions is not particularly limited, but the total amount of polyalkyleneimine N-oxide segments in the protective polymer is not limited. When the number of nitrogen atoms is 100 mol, the metal is usually in the range of 1 to 20,000 mol, preferably in the range of 1 to 10,000 mol, particularly preferably in the range of 50 to 7,000 mol.

  In the method for producing a metal colloid solution of the present invention, the method of mixing the medium in which the protective polymer is dispersed or dissolved with the metal salt or ionic solution is not particularly limited, and the protective polymer is dispersed. Alternatively, a method of adding a metal salt or ionic solution to a dissolved medium, a reverse method thereof, or a method of mixing while simultaneously charging in another container may be used. A mixing method such as stirring is not particularly limited.

  Moreover, the addition method of a reducing agent is not limited, For example, a reducing agent can be mixed as it is, or it dissolves and disperses | distributes in aqueous solution or another solvent. Also, the order of adding the reducing agent is not limited. Even if the reducing agent is added to the protective polymer solution or dispersion in advance, the reducing agent is added at the same time when the metal salt or ionic solution is mixed. Furthermore, after mixing the protective polymer solution or dispersion and the metal salt or ionic solution, after several days or weeks, a method of mixing the reducing agent may be used.

  When the metal salt used in the production method of the present invention or an ionic solution thereof is added to a medium in which the protective polymer is dispersed or dissolved, it is left as it is or in an aqueous solution regardless of the O / W system or W / O system. It is good to add it after adjusting. Since metal ions such as silver, gold, palladium and platinum are coordinated to the alkyleneimine N-oxide unit in the polymer and then spontaneously reduced at room temperature or in a heated state, By placing or stirring, metal nanoparticles can be obtained, and a metal colloid solution that is a dispersion of a complex protected with a protective polymer can be obtained. As described above, in order to efficiently reduce metal ions, A reducing agent is preferably used, and the colloidal metal solution can be obtained by standing or stirring at room temperature or warming. At this time, the reducing agent is preferably adjusted as it is or in an aqueous solution. The temperature for heating varies depending on the type of the protective polymer, the metal used, the medium, the type of the reducing agent, etc., but is generally 100 ° C. or lower, preferably 80 ° C. or lower.

  As described above, by reducing metal ions, metal nanoparticles are precipitated, and the surface of the particles is protected by the protective polymer and stabilized. The solution after the reduction reaction contains impurities such as a reducing agent, counter ions of metal ions, and protective polymers that are not involved in the protection of metal nanoparticles, and as such, sufficient performance as a conductive material is exhibited. I can't. Accordingly, a purification step for removing the impurities and the like is necessary. However, the protective polymer of the present invention has a high protective ability, so that a poor solvent is added to the reaction solution to protect the metal nanoparticles with the protective polymer. It is possible to precipitate the complex efficiently. The precipitated complex can also be concentrated or isolated using a process such as centrifugation. After the concentration, the non-volatile content (concentration) is prepared with a desired medium according to the use of the metal colloid solution and applied to various uses.

  The content of the metal nanoparticles in the metal colloid solution obtained in the present invention is not particularly limited, but if the content is too small, the properties of the metal nanoparticles as a colloid solution are difficult to appear and too much. The relative weight of the metal nanoparticles in the colloidal solution increases, and the balance between the relative weight and the dispersing power of the protective polymer is expected to lead to insufficient stability of the colloidal solution, as well as the alkylene in the protective polymer. From the viewpoint of reducing ability and coordination ability due to the imine N-oxide unit, the nonvolatile content in the metal colloid solution is preferably in the range of 10 to 80% by mass, particularly 20 to 70% by mass. It is preferable that it is the range of these. The content of the metal nanoparticles in the non-volatile content is preferably 93% by mass or more, particularly 95% by mass or more, from the viewpoint of the ability to develop conductivity when using a colloidal solution as a conductive material. Preferably there is.

  The particle size of the metal nanoparticles contained in the non-volatile content of the metal colloid solution obtained in the present invention is not particularly limited, but in order for the metal colloid solution to have higher dispersion stability, the metal nanoparticles The particle diameter of the particles is preferably 1 to 70 nm, more preferably 5 to 50 nm.

  In general, metal nanoparticles in the size region of several tens of nm have characteristic optical absorption due to surface plasmon excitation, depending on the metal species. Therefore, by measuring the plasmon absorption of the metal colloid solution obtained in the present invention, it is possible to confirm that the metal is present as fine particles of nanometer order in the solution. It is also possible to observe the average particle size, the distribution width, etc. in a TEM (transmission electron microscope) photograph of the film obtained by casting the film.

  The colloidal metal solution obtained in the present invention is stably dispersed for a long period of time in any medium, so that its use is not limited. For example, catalysts, electronic materials, magnetic materials, optical materials, various sensors It can be used in a very wide range of fields such as color materials and medical examination applications. From the point that the metal species that can be contained and the ratio thereof can be easily adjusted, it is possible to efficiently exhibit the effect according to the purpose. Furthermore, since it is stably dispersed over a long period of time, it can be used for long-term use and long-term storage, and is highly useful. In addition, the method for producing a metal colloid solution of the present invention is highly advantageous as an industrial production method because it requires almost no complicated steps or precise condition settings.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” represents “mass%”.

In the following examples, the equipment and measurement methods used are as follows.
¹ H-NMR: manufactured by JEOL Ltd., AL300, 300 Hz
Particle size measurement: FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.
Plasmon absorption spectrum: manufactured by Hitachi, Ltd., UV-3500

Confirmation of Structure of Protected Polymer by ¹ H-NMR After concentrating about 3 mL of the solution of the protected polymer and sufficiently drying under reduced pressure, the residue was reduced to about 0.0% of a solvent for NMR measurement such as 0.03% tetramethylsilane-containing deuterated chloroform. This was dissolved in 8 mL, put into a glass NMR measurement sample tube having an outer diameter of 5 mm, and a ¹ H-NMR spectrum was obtained using a JEOL JNM-LA300 type nuclear magnetic resonance absorption spectrum measuring apparatus. The chemical shift value δ was expressed using tetramethylsilane as a reference substance.

Particle size measurement by dynamic light scattering method A part of the metal colloid solution was diluted with purified water, and the particle size distribution and average particle size were measured with an FPAR-1000 type concentrated particle size analyzer (Otsuka Electronics Co., Ltd.). .

Measurement of metal content in non-volatile materials by thermogravimetric analysis About 1 mL of a metal colloid solution is placed in a glass sample bottle, heated and concentrated in a nitrogen water stream in a boiling water bath, and the residue is further vacuum-dried at 50 ° C. for 8 hours or more. Obtained. 2-10 mg of this non-volatile material is precisely weighed on an aluminum pan for thermogravimetric analysis and placed on an EXSTAR TG / DTA6300 differential thermogravimetric analyzer (manufactured by Seiko Instruments Inc.), under an air stream from room temperature to 500 ° C. every minute The temperature was raised at a rate of 10 ° C., and the weight loss rate associated with heating was measured. The silver content in the nonvolatile material was calculated by the following formula.
Metal content (%) = 100-weight reduction rate (%)

Measurement of resistivity of metal thin film obtained from metal colloid solution About 0.5 mL of the metal colloid solution was dropped on the top of a clean glass plate of 2.5 × 5 cm, and a bar coater No. 8 was used as a coating film. The produced coating film was air-dried and then heated in a hot air dryer at 125 ° C. and 180 ° C. for 30 minutes to obtain a fired coating film. The thickness of the obtained fired coating film was measured using an optical C130 type real color confocal microscope (Lasertec), and then the surface resistivity (Ω / □) was measured by Loresta-EP MCP-T360 type low resistivity. Using a meter (manufactured by Mitsubishi Chemical Co., Ltd.), the measurement was performed according to JIS K7194 “Resistivity Test of Conductive Plastic by 4-Probe Method”. The coating thickness showed a constant value of approximately 0.3 μm according to the above conditions, and the volume resistivity (Ωcm) was calculated from the thickness and the surface resistivity (Ω / □) by the following formula.
Volume resistivity (Ωcm) = Surface resistivity (Ω / □) × Thickness (cm)

Synthesis Example 1 Synthesis of Tosylated Polyethylene Glycol Monomethyl Ether Under a nitrogen atmosphere, a mixed solution of methoxypolyethylene glycol [Mn = 2,000] 20.0 g (10.0 mmol), pyridine 8.0 g (100.0 mmol), and chloroform 20 ml. A chloroform (30 ml) solution containing 9.6 g (50.0 mmol) of p-toluenesulfonic acid chloride was added dropwise for 30 minutes while stirring with ice cooling. After completion of dropping, the mixture was further stirred at a bath temperature of 40 ° C. for 4 hours. After completion of the reaction, 50 ml of chloroform was added to dilute the reaction solution. Subsequently, after sequentially washing with 100 ml of 5% hydrochloric acid aqueous solution, 100 ml of saturated aqueous sodium hydrogen carbonate solution and 100 ml of saturated saline solution, it was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The obtained solid was washed several times with hexane, filtered, and dried under reduced pressure at 80 ° C. to obtain 22.0 g of a tosylated product.

The measurement result of ¹ H-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) of the obtained product is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm) = 7.8 (d, 2H, J = 7.8 Hz, tosyl group), 7.3 (d, 2H, J = 7.8, tosyl group), 4.2 (t, 2H, J = 4.2 Hz, sulfonic acid ester adjacent position), 3.6-3.5 (m, PEGM methylene), 3.4 (s, 3H, PEGM chain terminal methoxy group) 2.4 (s, 3H, tosyl group) Methyl).

Synthesis Example 2 Precursor of Protective Polymer (1): Synthesis of Polyethyleneimine-b-Polyethylene Glycol Copolymer 19.3 g (9.0 mmol) of tosylated polyethylene glycol obtained in Synthesis Example 1 above, and branched polyethyleneimine 30.0 g (3.0 mmol) (manufactured by Nippon Shokubai Co., Ltd., Epomin SP200) was dissolved in 270 ml of N, N-dimethylacetamide, 0.18 g of potassium carbonate was added, and the mixture was stirred at 100 ° C. for 6 hours in a nitrogen atmosphere. After completion of the reaction, the solid matter was removed, followed by concentration under reduced pressure at 70 ° C., and a mixture of 200 ml of ethyl acetate and 600 ml of hexane was added to the residue to obtain a precipitate. The precipitate was dissolved in 120 ml of chloroform and reprecipitated again by adding a mixed solvent of 200 ml of ethyl acetate and 600 ml of hexane. This was separated by filtration and dried under reduced pressure to obtain 47.1 g of a pale yellow solid (yield 97%).

The measurement results of ¹ H-NMR, ¹³ C-NMR, ¹⁵ N-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) and elemental analysis of the obtained product are shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm) = 3.60 (m, PEGM methylene), 3.25 (s, 3H, PEGM chain terminal methoxy group), 2.70 to 2.40 (m, branched PEI ethylene).
¹³ C-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 39.0 (m), 46.0 (m), 48.0 (m), 51.0 (m), 53.0 (m), 56.0 (m) (more branched PEI Ethylene), 59.0 (s), 70.0 (m), 71.5 (m) (more PEGM methylene and terminal methoxy groups).
¹⁵ N-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 16.0 (m), 27.0-33.0 (m)
Measurement results of elemental analysis: C (53.9%), H (10.4%), N (18.2%)

Synthesis Example 3 Precursor of protected polymer (2): Synthesis of polyethyleneimine-b-polyethylene glycol-b-bisphenol A type epoxy resin EPICLON AM-040-P (manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent 933) 37.4 g (20 mmol), 2.72 g (16 mmol) of 4-phenylphenol was dissolved in 100 mL of N, N-dimethylacetamide, 0.52 mL of an ethanol solution of 65% ethyltriphenylphosphonium acetate was added, and under a nitrogen atmosphere, The reaction was carried out at 120 ° C. for 6 hours. After standing to cool, it was dropped into a large amount of water, and the resulting precipitate was washed with a large amount of water. The residue was dried under reduced pressure to obtain a modified bisphenol A type epoxy resin. The yield of the obtained product was 98%. ^{As a result of 1} H-NMR measurement and considering the integration ratio of epoxy groups, 0.95 epoxy rings remain in one molecule of bisphenol A type epoxy resin, and the product is a monofunctional epoxy resin having a bisphenol A skeleton. It was confirmed that.

The measurement results of ¹ H-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) of the obtained monofunctional epoxy resin are shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 7.55 to 6.75 (m), 4.40 to 3.90 (m), 3.33 (m), 2.89 (m), 2.73 (m), 1. 62 (s)

  A solution of 3.2 g (1.6 mmol) of the modified epoxy resin in acetone (50 mL) was added to a solution of 20 g (0.8 mmol) of the polyethyleneimine-b-polyethylene glycol copolymer obtained in Synthesis Example 2 in methanol (150 mL). After dropwise addition in a nitrogen atmosphere, the mixture was stirred at 50 ° C. for 2 hours. After completion of the reaction, the solvent was distilled off under reduced pressure and further dried under reduced pressure to obtain a polyethyleneimine-b-polyethylene glycol-b-bisphenol A type epoxy resin. The yield was 100%.

The measurement result of ¹ H-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) of the obtained product is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm) = 7.55 to 6.75 (m), 4.40 to 3.90 (m), 3.60 (m), 3.25 (s), 2.70 to 2.40 (m) ), 1.62 (s).

Example 1 Oxidation 1 of Precursor of Protective Polymer (1) (Oxidation Reaction 1 of Polyethyleneimine-b-Polyethylene Glycol Copolymer): Synthesis of Protective Polymer (1-1) Protective polymer obtained in Synthesis Example 2 ( After dissolving 36.6 g (N equivalent, 531 mmol) of the polyethyleneimine-b-polyethylene glycol copolymer which is the precursor of 1) in 100 mL of pure water, 35% hydrogen peroxide solution 5. 68 g (58.4 mmol, 11 mol% with respect to N equivalent) was gradually added to carry out the oxidation reaction for 5 hours, and a protective polymer (1-1) having a polyethyleneimine N-oxide chain as a product and a hydrophilic segment was obtained. Obtained quantitatively.

The measurement results of ¹ H-NMR and ¹³ C-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) and elemental analysis of the obtained product are shown below.
¹ H-NMR (DMSO-d ₆ ) measurement result:
δ (ppm) = 3.6 (m, PEGM methylene), 3.3 to 3.2 (m, N-oxide ethylene), 3.25 (s, 3H, PEGM chain terminal methoxy group), 2.9 ( m, N-oxide ethylene), 2.7-2.4 (m, branched PEI ethylene).
¹³ C-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 36.0 (m, N-oxide ethylene), 39.0 (m), 43.0 (m, N-oxide ethylene), 46.0 (m), 48.0 (m), 51.0 (m), 53.0 (m), 56.0 (m), 59.0 (s), 63.0-68.0 (m, N-oxide ethylene), 70.0 (m) 71.5 (s).
Elemental analysis measurement results: C (52.9%), H (10.0%), N (17.5%)

^{In the 1} H-NMR measurement, in the branched PEI ethylene of 2.40 to 2.70 ppm, the tertiary amine peak of 2.40 to 2.55 ppm with a higher magnetic field decreased, and the integration ratio decreased. The peaks of 55 to 2.60 ppm secondary amine and 2.60 to 2.70 ppm primary amine remained almost unchanged. Similarly, in the ¹³ C-NMR measurement results, the tertiary amine peak at 51.0 to 56.0 ppm decreased, but the peaks of the secondary amine and the primary amine at 39.0 to 51.0 ppm remained almost unchanged. Further, from the integral ratio of elemental analysis and NMR measurement, it is considered that about 11.0 to 15.0% of the total nitrogen (N) of the precursor compound was oxidized to N-oxide.

Example 2 Oxidation 2 of Precursor of Protective Polymer (1) (Oxidation Reaction 2 of Polyethyleneimine-b-Polyethylene Glycol Copolymer): Synthesis of Protective Polymer (1-2) Protective polymer obtained in Synthesis Example 2 ( After dissolving 36.6 g (N equivalent, 531 mmol) of the polyethyleneimine-b-polyethylene glycol copolymer which is the precursor of 1) in 100 mL of pure water, 35% hydrogen peroxide solution 15. 5 g (159.3 mmol, 30 mol% with respect to N equivalent) was gradually added to carry out the oxidation reaction for 5 hours, and a protected polymer (1-2) having a polyethyleneimine N-oxide chain as a product and a hydrophilic segment was obtained. Obtained quantitatively.

The measurement results of ¹ H-NMR and ¹³ C-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) and elemental analysis of the obtained product are shown below.
¹ H-NMR (DMSO-d ₆ ) measurement result:
δ (ppm) = 3.6 (m, PEGM methylene), 3.3 to 3.2 (m, N-oxide ethylene), 3.25 (s, 3H, PEGM chain terminal methoxy group), 2.9 ( m, N-oxide ethylene), 2.7-2.4 (m, branched PEI ethylene).
¹³ C-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 36.0 (m, N-oxide ethylene), 39.0 (m), 43.0 (m, N-oxide ethylene), 46.0 (m), 48.0 (m), 51.0 (m), 53.0 (m), 56.0 (m), 59.0 (s), 63.0-68.0 (m, N-oxide ethylene), 70.0 (m) 71.5 (s).
Measurement results of elemental analysis: C (52.5%), H (10.1%), N (16.2%)

Higher magnetic field 2.40 to 2.55 ppm tertiary amine peak is almost eliminated in 2.40 to 2.70 ppm branched PEI ethylene by ¹ H-NMR measurement, and 2.55 to 2.60 ppm secondary. The amine and the primary amine peak at 2.60-2.70 ppm decreased, and the integration ratio decreased. Similarly, in the ¹³ C-NMR measurement results, the tertiary amine peak at 51.0 to 56.0 ppm was almost eliminated, and the peaks of the secondary amine and primary amine at 39.0 to 51.0 ppm were small. Further, from the integral ratio of elemental analysis and NMR measurement, it is considered that about 30.0 to 39.0% of the total nitrogen (N) of the precursor compound was oxidized to N-oxide.

Example 3 Oxidation 3 of Precursor of Protective Polymer (1) (Oxidation Reaction 3 of Polyethyleneimine-b-Polyethylene Glycol Copolymer): Synthesis of Protective Polymer (1-3) Protective polymer obtained in Synthesis Example 2 ( After dissolving 36.6 g (N equivalent, 531 mmol) of the polyethyleneimine-b-polyethylene glycol copolymer that is the precursor of 1) in 100 mL of pure water, 35% hydrogen peroxide solution 25.25% in an ice bath with stirring. 8 g (265.5 mmol, 50 mol% with respect to N equivalent) was gradually added to carry out the oxidation reaction for 5 hours, and a protected polymer (1-3) having a polyethyleneimine N-oxide chain as a product and a hydrophilic segment was obtained. Obtained quantitatively.

The measurement results of ¹ H-NMR, ¹³ C-NMR and ¹⁵ N-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) and elemental analysis of the obtained product are shown below.
¹ H-NMR (DMSO-d ₆ ) measurement result:
δ (ppm) = 3.6 (m, PEGM methylene), 3.3 to 3.2 (m, N-oxide ethylene), 3.25 (s, 3H, PEGM chain terminal methoxy group), 2.9 ( m, N-oxide ethylene), 2.7-2.5 (m, branched PEI ethylene).
¹³ C-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 36.0 (m, N-oxide ethylene), 39.0 (m), 43.0 (m, N-oxide ethylene), 46.0 (m), 48.0 (m), 51.0 (m), 53.0 (m), 59.0 (s), 63.0-68.0 (m, N-oxide ethylene), 70.0 (m), 71.5 (s) .
¹⁵ N-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 15.0 (m), 20.0-30.0 (m), 112.0-120.0 (m, N-oxide ethylene), 128.0-132.0 (m, N -Oxide ethylene).
Measurement results of elemental analysis: C (50.9%), H (9.8%), N (15.9%)

Higher magnetic field 2.40-2.55 ppm tertiary amine peak disappears in 2.40-2.70 ppm branched PEI ethylene by ¹ H-NMR measurement, 2.55-2.60 ppm secondary amine And the primary amine peak from 2.60 to 2.70 ppm decreased, and the integration ratio decreased. Similarly, in the ¹³ C-NMR measurement result, the tertiary amine peak of 51.0 to 56.0 ppm disappeared, and the peak of the secondary amine and primary amine of 39.0 to 51.0 ppm became small. Similarly, in the ¹⁵ N-NMR measurement results, the tertiary amine peak of 30.0 to 33.0 ppm disappeared, and the peaks of the secondary and primary amines of 20.0 to 30.0 ppm and 15.0 ppm became small. From the integral ratio of elemental analysis and NMR measurement, it is considered that about 50.0 to 61.0% of the total nitrogen (N) of the precursor compound was oxidized to N-oxide.

Example 4 Oxidation 4 of Precursor of Protective Polymer (1) (Oxidation Reaction 4 of Polyethyleneimine-b-Polyethylene Glycol Copolymer): Synthesis of Protective Polymer (1-4) Protective polymer obtained in Synthesis Example 2 ( After dissolving 36.6 g (N equivalent, 531 mmol) of the polyethyleneimine-b-polyethylene glycol copolymer that is the precursor of 1) in 100 mL of pure water, 35% hydrogen peroxide solution 36.35% in an ice bath with stirring. 1 g (371.7 mmol, 70 mol% with respect to N equivalent) was gradually added to carry out the oxidation reaction for 5 hours, and a protected polymer (1-4) having a polyethyleneimine N-oxide chain as a product and a hydrophilic segment was obtained. Obtained quantitatively.

The measurement results of ¹ H-NMR and ¹³ C-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) and elemental analysis of the obtained product are shown below.
¹ H-NMR (DMSO-d ₆ ) measurement result:
δ (ppm) = 3.6 (m, PEGM methylene), 3.3 to 3.2 (m, N-oxide ethylene), 3.25 (s, 3H, PEGM chain terminal methoxy group), 2.9 ( m, N-oxide ethylene), 2.70 to 2.55 (m, branched PEI ethylene).
¹³ C-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 36.0 (m, N-oxide ethylene), 39.0 (m), 43.0 (m, N-oxide ethylene), 46.0 (m), 48.0 (m), 51.0 (m), 59.0 (s), 63.0-68.0 (m, N-oxide ethylene), 70.0 (m), 71.5 (s).
Measurement results of elemental analysis: C (49.6%), H (9.3%), N (15.1%)

Higher magnetic field 2.40-2.55 ppm tertiary amine peak disappears in 2.40-2.70 ppm branched PEI ethylene by ¹ H-NMR measurement, 2.55-2.60 ppm secondary amine And the primary amine peak from 2.60 to 2.70 ppm was almost gone. Similarly, in the ¹³ C-NMR measurement result, the tertiary amine peak of 51.0 to 56.0 ppm disappeared, and the peak of the secondary amine and primary amine of 39.0 to 51.0 ppm almost disappeared. Further, from the integral ratio of elemental analysis and NMR measurement, it is considered that about 70.0-76.0% of the total nitrogen (N) of the precursor compound was oxidized to N-oxide.

Example 5 Oxidation 5 of Precursor of Protective Polymer (1) (Oxidation Reaction 5 of Polyethyleneimine-b-Polyethylene Glycol Copolymer): Synthesis of Protective Polymer (1-5) Protective polymer obtained in Synthesis Example 2 ( After dissolving 36.6 g (N equivalent, 531 mmol) of the polyethyleneimine-b-polyethylene glycol copolymer which is the precursor of 1) in 100 mL of pure water, 35% hydrogen peroxide solution 51. 6 g (531.0 mmol, 100 mol% with respect to N equivalent) was gradually added to carry out the oxidation reaction for 5 hours, and a protective polymer (1-5) having a polyethyleneimine N-oxide chain as a product and a hydrophilic segment was obtained. Obtained quantitatively.

The measurement results of ¹ H-NMR and ¹³ C-NMR (manufactured by JEOL Ltd., AL300, 300 MHz) and elemental analysis of the obtained product are shown below.
¹ H-NMR (DMSO-d ₆ ) measurement result:
δ (ppm) = 3.6 (m, PEGM methylene), 3.3 to 3.2 (m, N-oxide ethylene), 3.25 (s, 3H, PEGM chain terminal methoxy group), 2.9 ( m, N-oxide ethylene).
¹³ C-NMR (DMSO-d ₆ ) measurement results:
δ (ppm) = 36.0 (m, N-oxide ethylene), 43.0 (m, N-oxide ethylene), 48.0 (m), 59.0 (s), 63.0 to 68.0 (M, N-oxide ethylene), 70.0 (m), 71.5 (s).
Measurement results of elemental analysis: C (48.0%), H (8.8%), N (14.1%)

Higher magnetic field 2.40 to 2.55 ppm tertiary amine peak, 2.55 to 2.60 ppm secondary amine and 2 in branched PEI ethylene from 2.40 to 2.70 ppm as determined by ¹ H-NMR. The primary amine peak from .60 to 2.70 ppm disappeared. Similarly, the ¹³ C-NMR measurement results were also freed from 51.0 to 56.0 ppm of tertiary amine peak, 39.0 to 51.0 ppm of secondary amine and primary amine peaks. Also, from the integral ratio of elemental analysis and NMR measurement, it is considered that N of 100% of the total nitrogen (N) of the precursor compound was oxidized to N-oxide.

Example 6 Oxidation of Protective Polymer (2) Precursor (Polyethyleneimine-b-Polyethylene Glycol-b-Bisphenol A Type Epoxy Resin Compound): Synthesis of Protective Polymer (2-1) Obtained in Synthesis Example 3 42.5 g (N equivalent, 531 mmol) of a polyethyleneimine-b-polyethylene glycol-b-bisphenol A type epoxy resin, which is a precursor of the protective polymer (2), was dissolved in 100 mL of pure water, and then stirred in an ice bath. 35% hydrogen peroxide solution 25.8 g (265.5 mmol, 50 mol% to N equivalent) was gradually added to carry out the oxidation reaction for 5 hours, and the product polyethyleneimine N-oxide chain, hydrophilic segment and hydrophobic The protective polymer (2-1) having a sex segment was quantitatively obtained.

The measurement result of ¹ H-NMR of the obtained product is shown below.
¹ H-NMR (DMSO-d ₆ ) measurement result:
δ (ppm) = 7.55 to 6.75 (m), 4.40 to 3.90 (m), 3.6 (m, PEGM methylene), 3.30 to 3.20 (m, N-oxide) Ethylene), 3.25 (s, PEGM chain terminal methoxy group), 2.9 (m, N-oxide ethylene), 2.70-2.50 (m, branched PEI ethylene), 1.62 (s).

Higher magnetic field 2.40-2.55 ppm tertiary amine peak disappears in 2.40-2.70 ppm branched PEI ethylene by ¹ H-NMR measurement, 2.55-2.60 ppm secondary amine And the primary amine peak from 2.60 to 2.70 ppm decreased, and the integration ratio decreased. From the integration ratio of the NMR measurement, it is considered that about 50.0-55.0% of the total nitrogen (N) of the precursor compound was oxidized to N-oxide.

Example 7 Synthesis of silver colloid solution by protective polymer (1-1) of Example 1 180 g of pure water in a 1 L reaction kettle and 13.5 g of an aqueous solution of the protective polymer (1-1) obtained in Example 1 above. N, N-dimethylaminoethanol (113 g, 1.27 mol) was added in order and stirred to prepare a mixed solution of a protective polymer and a reducing agent. Separately, 72.0 g (0.424 mol) of silver nitrate was dissolved in 120 g of pure water, and the prepared silver nitrate aqueous solution was dropped at room temperature over about 30 minutes, and then stirred at 40 ° C. for 4 hours. After completion of the reaction and cooling, 1.4 L of poor solvent acetone (about 3 times volume of the reaction mixture) was added and stirred for 5 minutes. The composite of silver nanoparticles and protective polymer settled and separated after standing for about 1 hour. After removing the supernatant, the produced sediment was centrifuged. After adding 80 g of pure water to the paste-like precipitate after centrifugation and dispersing well, the residual acetone is distilled off from the solvent and concentrated under reduced pressure until the non-volatile matter is about 60%. (46.0 g as a non-volatile material, yield 96%) was obtained. As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 96.0%.

Example 8 Synthesis of silver colloid solution with protective polymer (1-2) of Example 2 Instead of 13.5 g of aqueous solution of protective polymer (1-1) obtained in Example 1, it was obtained in Example 2 above. Except for using 14.5 g of the obtained aqueous solution of the protective polymer (1-2), 73.0 g of a silver colloid aqueous solution having a non-volatile content of about 60% was obtained in the same manner as in Example 7 (45% as a non-volatile material). .6 g, yield 95%). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 96.2%.

Example 9 Synthesis of silver colloid solution with protective polymer (1-3) of Example 3 Instead of 13.5 g of aqueous solution of protective polymer (1-1) obtained in Example 1, it was obtained in Example 3 above. Except for using 15.5 g of the obtained aqueous solution of the protective polymer (1-3), 74.0 g of an aqueous silver colloid solution containing about 60% non-volatiles was obtained in the same manner as in Example 7 (46 as non-volatiles). 0.0 g, yield 96%). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 95.8%.

Example 10 Synthesis of silver colloid solution with protective polymer (1-4) of Example 4 Instead of 13.5 g of aqueous solution of protective polymer (1-1) obtained in Example 1, it was obtained in Example 4 above. Except for using 16.4 g of the obtained aqueous solution of the protective polymer (1-4), 75.0 g of a silver colloid aqueous solution having a non-volatile content of about 60% was obtained in the same manner as in Example 7 (45% as a non-volatile material). 0.1 g, 94% yield). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 96.3%.

Example 11 Synthesis of silver colloid solution with protective polymer (1-5) of Example 5 Instead of 13.5 g of the aqueous solution of protective polymer (1-1) obtained in Example 1, it was obtained in Example 5 above. Except for using 17.9 g of the obtained aqueous solution of the protective polymer (1-5), 70.0 g of a silver colloid aqueous solution having a non-volatile content of about 60% was obtained in the same manner as in Example 7 (44 as the non-volatile material). 0.1 g, yield 92%). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 96.5%.

Example 12 Synthesis of silver colloid solution with protective polymer (2-1) of Example 6 Instead of 13.5 g of the aqueous solution of protective polymer (1-1) obtained in Example 1, it was obtained in Example 6 above. Except for using 16.5 g of the obtained aqueous solution of the protective polymer (2-1), 76.0 g of an aqueous silver colloid solution having a non-volatile content of about 60% was obtained in the same manner as in Example 7 (45% as a non-volatile material). .6 g, yield 95%). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 95.8%.

Comparative Example 1 Synthesis of Silver Colloid Solution Using Compound of Synthesis Example 2 Precursor Compound 3 Obtained in Synthesis Example 2 Instead of 13.5 g of the aqueous solution of the protective polymer (1-1) obtained in Example 1 Except for using an aqueous solution prepared by dissolving 9.5 g of pure water in an amount of 9.5 g, 74.0 g of an aqueous silver colloid solution containing about 60% non-volatiles was obtained in the same manner as in Example 7 (45% as non-volatiles). .6 g, yield 95%). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 96.1%.

Comparative Example 2 Synthesis of Silver Colloid Solution Using Compound of Synthesis Example 3 Precursor Compound 4 obtained in Synthesis Example 3 above instead of 13.5 g of the aqueous solution of the protective polymer (1-1) obtained in Example 1 Except for using an aqueous solution prepared by dissolving 9.5 g of pure water in an amount of 0.1 g, 77.0 g of an aqueous silver colloid solution containing about 60% non-volatiles was obtained in the same manner as in Example 7 (46 as non-volatiles). 0.0 g, yield 96%). As a result of thermal analysis (Tg / DTA), the silver content in the non-volatile material was 95.7%.

Using the silver colloid solutions obtained in Examples 7 to 12 and Comparative Examples 1 and 2, the resistance value and the average particle diameter of the metal thin film were measured according to the above. In addition, the amount used and the time required for the precipitation treatment with acetone during synthesis are shown in the table below. Furthermore, the stability was evaluated from the appearance when the obtained silver colloid solution was left to stand at room temperature (25 to 35 ° C.) for 1 week. The results are shown in Tables 1-2. In Table 1, O.D. L. Represents overscale.

Claims (12)

1. A metal nanoparticle-protecting polymer comprising, in one molecule, a polyalkyleneimine N-oxide segment (A) obtained by oxidizing a nitrogen atom in a polyalkyleneimine and a hydrophilic segment (B). Furthermore, the metal nanoparticle protection polymer of Claim 1 which has a hydrophobic segment (C) in 1 molecule. The metal nanoparticle protective polymer according to claim 1 or 2, wherein the hydrophilic segment (B) comprises a polyoxyalkylene chain. The metal nanoparticle protective polymer according to claim 2 or 3, wherein the hydrophobic segment (C) has a structure derived from an epoxy resin. The metal nanoparticle protective polymer according to any one of claims 1 to 4, wherein the number of units of the alkyleneimine in the polyalkyleneimine N-oxide segment (A) is in the range of 5 to 2,500. The metal nanoparticle protective polymer according to any one of claims 1 to 5, wherein the weight average molecular weight is in the range of 1,000 to 100,000. The manufacturing method of the metal nanoparticle protection polymer characterized by oxidizing the precursor compound which has a polyalkylene imine segment (a) and a hydrophilic segment (B) in 1 molecule using an oxidizing agent. A composite in which metal nanoparticles are protected with a polymer having a polyalkyleneimine N-oxide segment (A) in which a nitrogen atom in polyalkyleneimine is oxidized in one molecule and a hydrophilic segment (B) Is a metal colloidal solution characterized by being dispersed in a medium. The metal colloid solution according to claim 8, wherein the metal nanoparticles are silver nanoparticles. The metal colloid solution according to claim 8 or 9, wherein a particle diameter of the metal nanoparticles is in a range of 5 to 50 nm. Reduction of metal ions in a medium in the presence of a polymer having a polyalkyleneimine N-oxide segment (A) obtained by oxidizing a nitrogen atom in polyalkyleneimine and a hydrophilic segment (B) in one molecule. To produce metal nanoparticles, a method for producing a metal colloid solution. The method for producing a metal colloid solution according to claim 11, wherein the metal nanoparticles are silver nanoparticles.