Method for producing copper nanoparticles

Abstract

To provide a copper nanoparticle production method capable of obtaining copper nanoparticles uniformly dispersed into water, alcohol or the like and not oxidized by temperatures, oxygen, acid or the like as a low temperature, high concentration and uniform dispersion liquid without using the atoms of metals other than copper, and to provide a copper nanoparticle production method capable of obtaining an antibacterial agent, an antiviral agent, an antifungal agent, a deodorizer or the like having uniformity and transparency by combining the obtained dispersion liquid with a titania nanoparticle-dispersed liquid having a small particle diameter.SOLUTION: A copper nanoparticle production method has a process of heating copper (II) acetylacetonato at 120°C or more in at least one kind of organic solvent selected from the group consisting of a compound expressed by R1R2N-R3-OH (expression 1) (in the expression 1, R1 and R2 are same or different and denote a hydrogen atom or an alkyl group, respectively. and R3 denotes an alkyl chain.) and a compound expressed by R4R5NCHO (expression 2) (in the expression 2, R4 and R5 are same or different and denote a hydrogen atom or an alkyl group, respectively.).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing copper nanoparticles. [Background technology]

[0002] Copper nanoparticles are used in conductive inks, catalysts, and other applications. However, producing copper nanoparticles at low temperatures and high concentrations is difficult, and they are generally produced by adding a reducing agent containing a metal element other than copper. Furthermore, copper nanoparticles are prone to surface oxidation, and are generally produced by protecting them with fatty acids or other solvents. However, copper nanoparticles protected with fatty acids or other solvents have problems, such as being difficult to dissolve in water or hydrophilic alcohols, and generating copper ions when they come into contact with acidic solutions.

[0003] On the other hand, copper ions, which are easily soluble in water, have antibacterial, antiviral, antifungal, and deodorizing effects. However, copper ions are skin sensitizers, and consideration is needed in technical fields where they are used in applications that involve skin contact.

[0004] A typical method for producing copper nanoparticles from copper salts is the polyol reduction method (Non-Patent Documents 1-11). Both methods use inorganic salts such as copper chloride and copper sulfate as raw materials, and either use a metal salt such as NaOH as a neutralizing agent (Non-Patent Documents 1-7) or an inorganic reducing agent containing metals other than Cu, such as NaBH4 (Non-Patent Documents 8-11). For this reason, unless a cleaning or separation process is performed after the reaction to remove metals other than Cu, anions, etc., substances other than copper nanoparticles will remain even if the product is used as a coating solution or calcined. Furthermore, there are examples of using microwaves to increase reactivity, but this requires special equipment and is not suitable for mass production (Non-Patent Documents 1 and 8). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Chem. Commun., 47, 7740 (2011) [Non-patent document 2] Mater.Lett., 59, 3933 (2005) [Non-patent document 3] Nanoscale Res. Lett., 4, 705 (2009) [Non-patent document 4] J. Mater. Chem., 3, 627 (1993) [Non-patent document 5] J. Mater.Chem., 21, 7062 (2011) [Non-patent document 6] Dalton Transactions, 39, 6496 (2011) [Non-Patent Document 7] Nanotechnology, 16, 3079 (2005) [Non-patent document 8] J.Cryst.Growth, 270, 722 (2004) [Non-Patent Document 9] J. Colloid Interface Sci., 311, 417 (2007) [Non-Patent Document 10] Colloids Surf.A, 360, 99 (2010) [Non-Patent Document 11] Adu.Funct.Mater., 18, 679 (2008) Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a method for producing copper nanoparticles that are uniformly dispersed in water, alcohols, etc. without using metal atoms other than copper and are not oxidized by temperature, oxygen, acid, etc. at low temperatures and at high concentrations. The object of the present invention is to obtain a uniform dispersion liquid.

[0007] Another object of the present invention is to obtain a uniform and transparent antibacterial agent, antiviral agent, antifungal agent, deodorizer, etc. by combining the obtained dispersion with a dispersion of small particle diameter titania nanoparticles. [Means for solving the problem]

[0008] In view of the above object, the present inventors have conducted intensive research and, as a result, in a method for producing copper nanoparticles, by combining a copper compound having a specific structure with a solvent having a specific structure, it is possible to easily obtain copper nanoparticles that are uniformly dispersed in water, ethanol, etc. The inventors have found that this can solve the above problem.

[0009] The inventors then conducted further research and completed the present invention.

[0010] That is, the present invention includes the following configurations.

[0011] Section 1. A method for producing copper nanoparticles, R 1 R 2 NR 3 -OH (Formula 1) (In formula 1, R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group. 3 indicates an alkyl chain.) A compound represented by the formula: R 4 R 5 NCHO (Formula 2) (In formula 2, R 4 , and R 5 are the same or different and each represents a hydrogen atom or an alkyl group. In at least one organic solvent selected from the group consisting of compounds represented by heating copper(II) acetylacetonate at 120°C or higher; A manufacturing method comprising:

[0012] Section 2. Item 2. The method for producing a product according to Item 1, wherein the compound represented by formula 1 is at least one organic solvent selected from the group consisting of 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 3-(dimethylamino)-1-propanol, and 1-(dimethylamino)-2-propanol.

[0013] Section 3. Item 2. The method according to item 1, wherein the compound represented by formula 2 is at least one organic solvent selected from the group consisting of N,N-dimethylformamide, N-methylformamide, and formamide.

[0014] Section 4. 4. The method according to any one of items 1 to 3, wherein the heating temperature is 120°C or higher and 150°C or lower.

[0015] Section 5. 5. The method according to any one of items 1 to 4, wherein the concentration of copper(II) acetylacetonate in the total mass of the reaction solution containing the copper(II) acetylacetonate and the organic solvent is 0.1 mass% or more and 2.0 mass% or less in terms of copper atoms.

[0016] Section 6. 6. The method according to any one of items 1 to 5, wherein the organic solvent further comprises at least one organic solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and anisole.

[0017] Section 7. 7. The method according to any one of items 1 to 6, wherein the organic solvent has a boiling point of 75°C or higher and 200°C or lower.

[0018] Section 8. 8. The method according to any one of items 1 to 7, wherein the organic solvent contains at least one organic solvent selected from the group consisting of the compound represented by formula 1 and the compound represented by formula 2 in a total amount of 0.01% by mass to 100% by mass.

[0019] Section 9. A method for producing an antibacterial agent, an antiviral agent, an antifungal agent, and / or a deodorant, comprising: (A) R 1 R 2 NR 3 -OH (Formula 1) (In formula 1, R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group. 3 indicates an alkyl chain.) A compound represented by the formula: R 4 R 5 NCHO (Formula 2) (In formula 2, R 4 , and R 5 are the same or different and each represents a hydrogen atom or an alkyl group. In at least one organic solvent selected from the group consisting of compounds represented by A step of heating copper (II) acetylacetonate at 120°C or higher to produce a copper nanoparticle dispersion; (B) A step of mixing the copper nanoparticle dispersion produced in the step (A) with the titania nanoparticle dispersion. Including, The titania nanoparticles have acetoxy groups bonded to at least some of the titanium atoms present on the surface, and when heated to 600°C using a thermogravimetric differential thermal analyzer, the mass loss at 200°C or higher is 5% by mass or more, and the particle size is 1 nm to 10 nm. Manufacturing method. [Effects of the Invention]

[0020] According to the present invention, a method for producing copper nanoparticles can be achieved without using reducing agents that are difficult to remove, such as metal salts. This method allows for the synthesis of copper nanoparticles that have a very small particle size, are highly active, can be coated transparently, are resistant to oxidation due to heat, oxygen, acid, etc., and are dispersible in water, hydrophilic alcohol, etc.

[0021] According to the present invention, in the method for producing copper nanoparticles, a copper compound having a specific structure and a solvent having a specific structure are used and stirred at a specific temperature, thereby obtaining a copper nanoparticle dispersion in a short time. Can be obtained.

[0022] According to the present invention, by mixing the obtained copper nanoparticle dispersion with titania nanoparticles, a composite thereof can be obtained in a highly dispersible state.

[0023] According to the present invention, a material containing a copper nanoparticle dispersion and titania nanoparticles can be used as a transparent and highly active antibacterial agent, antiviral agent, antifungal agent, deodorizer, etc. [Brief explanation of the drawings]

[0024] [Figure 1] 1 shows an embodiment of the present invention. Fig. 1 shows the results of SEM observation after spin-coating the copper nanoparticle dispersion obtained in Example 1 onto a silicon wafer and baking it. Nanoparticles of 100 nm or less were confirmed. [Figure 2] 2 shows an embodiment of the present invention, and FIG. 2 shows the results of ESCA analysis of the copper nanoparticle dispersion obtained in Example 1. The copper nanoparticles are metallic copper. [Figure 3] 3 is a diagram illustrating an embodiment of the present invention, and shows the results of XRD analysis of the crystal structure of the copper nanoparticle dispersion obtained in Example 1. The copper nanoparticles are metallic copper. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below.

[0026] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0027] In this specification, when a numerical range is expressed as "A to B," it means "not less than A and not more than B."

[0028] 1. Manufacturing method of copper nanoparticles The method for producing copper nanoparticles of the present invention includes: R 1 R 2 NR 3 -OH (Formula 1) (In formula 1, R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group. 3 indicates an alkyl chain.) A compound represented by the formula: R 4 R 5 NCHO (Formula 2) (In formula 2, R 4 , and R 5 are the same or different and each represents a hydrogen atom or an alkyl group. In at least one organic solvent selected from the group consisting of compounds represented by heating copper(II) acetylacetonate at 120°C or higher; Includes.

[0029] (1)Copper-based compounds In the present invention, copper (II) acetylacetonate, an organic copper complex, is used as the raw material for copper nanoparticles. Copper (II) acetylacetonate is insoluble in water, does not ionize, and forms a resonance structure.

[0030] [ka]

[0031] In the present invention, copper nanoparticles are obtained by reducing copper(II) acetylacetonate.

[0032] (2) Organic solvent In the present invention, the organic solvent used is a solvent having a nitrogen atom (N).

[0033] The solvent may further be mixed with a solvent having a weak reducing power, such as glycols or alcohols, or may be mixed with a solvent having no reducing power.

[0034] Solvents containing nitrogen atoms (N) are classified as R 1 R 2 NR 3 It is a compound represented by the formula: 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group. 3 indicates an alkyl chain.

[0035] Solvents containing nitrogen atoms (N) are classified as R 4 R 5 It is a compound represented by NCHO (Formula 2). In Formula 2, R 4 , and R 5 may be the same or different and each represents a hydrogen atom or an alkyl group.

[0036] The solvent is at least one organic solvent selected from the group consisting of compounds represented by formula 1 and compounds represented by formula 2.

[0037] The alkyl group and alkyl chain are preferably linear, branched, or cyclic alkyl groups and alkyl chains. Specific examples include linear or branched alkyl groups and alkyl chains having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and 1-ethylpropyl; linear or branched alkyl groups and alkyl chains having 1 to 18 carbon atoms, including n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl; and cyclic alkyl groups and alkyl chains having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0038] The alkyl group and alkyl chain are preferably methyl, ethyl, or the like.

[0039] The solvent having a nitrogen atom, the compound represented by Formula 1, is preferably at least one organic solvent selected from the group consisting of 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 3-(dimethylamino)-1-propanol, and 1-(dimethylamino)-2-propanol.

[0040] The solvent having a nitrogen atom, which is the compound represented by formula 2, is preferably at least one organic solvent selected from the group consisting of N,N-dimethylformamide, N-methylformamide, and formamide.

[0041] More preferred examples of the solvent having a nitrogen atom include 2-(dimethylamino)ethanol, N-methylformamide, and N,N-dimethylformamide.

[0042] In the present invention, the organic solvent preferably further contains at least one organic solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and anisole as a solvent not containing a nitrogen atom (N).

[0043] The solvent containing no nitrogen atom is more preferably ethylene glycol, propylene glycol, anisole, or the like.

[0044] In the present invention, the total content of at least one organic solvent (a solvent having a nitrogen atom) selected from the group consisting of the compound represented by Formula 1 and the compound represented by Formula 2 is preferably 0.01% by mass to 100% by mass in the organic solvent. By adjusting the ratio of the solvent having a nitrogen atom in the organic solvent to fall within the above range, even a very small amount can be used to obtain a copper nanoparticle dispersion with a high concentration, compared to using only a solvent that does not contain nitrogen atoms and has reducing properties.

[0045] The total content of the solvent having a nitrogen atom in the organic solvent is preferably 0.01% by mass or more and 100% by mass or less, more preferably 0.1% by mass or more and 100% by mass or less, based on the weight of the entire solvent.

[0046] The upper limit of the total content of the solvent having a nitrogen atom is preferably 100% by mass. By using only the solvent having a nitrogen atom (single use), the reducing power is strong and the reduction reaction proceeds smoothly.

[0047] In another embodiment of the organic solvent to be used, the greater the amount of the solvent having a nitrogen atom in the organic solvent, the faster the reaction rate. However, since the solvent becomes more basic due to decomposition during heating, a smaller amount is desirable when the organic solvent is to be mixed with an acidic substance later. Therefore, the amount of the solvent having a nitrogen atom in the organic solvent is more preferably 0.01% by mass or more and 10% by mass or less, and particularly preferably 0.01% by mass or more and 5% by mass or less.

[0048] When mixed with an acidic titania sol, a phenomenon may occur in which dispersibility decreases due to basic substances decomposed from the solvent having nitrogen atoms. To prevent this, it is preferable to mix a solvent that does not contain nitrogen atoms (e.g., ethylene glycol) with the solvent having nitrogen atoms.

[0049] The organic solvent preferably contains no nitrogen atoms in an amount of 90% by mass or more and 99.9% by mass or less, and particularly preferably 95% by mass or more and 99.9% by mass or less.

[0050] In the present invention, the boiling point of the organic solvent is preferably 60° C. or higher and 250° C. or lower. The organic solvent is more preferably an organic solvent having a boiling point of 75° C. or higher and 200° C. or lower. In consideration of the reaction temperature, the organic solvent is preferably 75° C. or higher, and in consideration of the removability from the copper nanoparticle dispersion, the organic solvent is preferably 200° C. or lower.

[0051] (3) Manufacturing method In the method for producing copper nanoparticles of the present invention, copper(II) acetylacetonate is mixed with the organic solvent and heated at 120° C. or higher to produce a copper nanoparticle dispersion.

[0052] If the heating temperature is low, copper(II) acetylacetonate tends to dissolve in the solvent and precipitate after cooling. If the heating temperature is high, the reaction proceeds smoothly. For safety reasons, it is preferable to heat below the boiling point of the organic solvent used. Heating can also be performed while some of the solvent is boiling.

[0053] The heating temperature is preferably 100°C or higher and 200°C or lower, more preferably 110°C or higher and 180°C or lower, and even more preferably 120°C or higher and 150°C or lower.

[0054] When the concentration of copper(II) acetylacetonate is low in the total mass of the reaction solution containing copper(II) acetylacetonate and an organic solvent, copper nanoparticles can be successfully purified. Increasing the concentration of copper(II) acetylacetonate improves the productivity of copper nanoparticles. The concentration of copper(II) acetylacetonate is adjusted to suppress the generation of large metallic copper particles.

[0055] The concentration of copper(II) acetylacetonate in the total mass of the reaction solution containing copper(II) acetylacetonate and the organic solvent is preferably 0.1 mass % or more and 2.0 mass % or less in terms of copper (Cu) atoms.

[0056] 2. Photocatalysts, antibacterial materials, antiviral materials, and antiviral coating solutions The copper nanoparticles of the present invention can be used in combination with a photocatalyst. By using the copper nanoparticles of the present invention in combination with a photocatalyst, it is possible to impart antibacterial, antiviral, antifungal, deodorizing, and other properties to a conventional photocatalyst that is activated only when irradiated with ultraviolet light, in a dark place, or the like, when irradiated with visible light.

[0057] The method for producing the antibacterial agent, antiviral agent, antifungal agent, and / or deodorant of the present invention comprises the steps of: (A) R 1 R 2 NR 3 -OH (Formula 1) (In formula 1, R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group. 3 indicates an alkyl chain.) A compound represented by the formula: R 4 R 5 NCHO (Formula 2) (In formula 2, R 4 , and R 5 are the same or different and each represents a hydrogen atom or an alkyl group. In at least one organic solvent selected from the group consisting of compounds represented by A step of heating copper (II) acetylacetonate at 120°C or higher to produce a copper nanoparticle dispersion; (B) The method includes a step of mixing the copper nanoparticle dispersion produced in the step (A) with a titania nanoparticle dispersion.

[0058] The titania nanoparticles contained in the titania nanoparticle dispersion have acetoxy groups bonded to at least some of the titanium atoms present on the surface, and when heated to 600°C using a thermogravimetric differential thermal analyzer, they experience a mass loss of 5% by mass or more at 200°C or higher, and have a particle size of 1 nm to 10 nm.

[0059] Titania does not refer only to titanium dioxide (TiO2), but also includes titanium dioxide with oxygen deficiency, such as titanium trioxide (Ti2O3), titanium monoxide (TiO), Ti4O7, and Ti5O9. Titania may contain groups other than Ti-O-Ti, such as terminal OH groups, that result from the synthesis of titanium oxide. Titania also includes those in which an organic acid or the like is bonded to the terminal OH group.

[0060] When copper ions are used, they generally have the potential to cause skin sensitization. When copper nanoparticles are used, they also have the potential to cause skin sensitization because they partially dissolve when in contact with an acidic photocatalyst, generating copper ions.

[0061] The copper nanoparticles of the present invention maintain their copper nanoparticle state even when they come into contact with an acidic solution, and are unlikely to cause skin sensitization.

[0062] The copper nanoparticles of the present invention can be uniformly dispersed in water or organic solvents without precipitating. The copper nanoparticles of the present invention are uniformly dissolved in, for example, water, ethanol, acetone, etc., to form a transparent brown solution.

[0063] The copper nanoparticles of the present invention can be used for antibacterial, antiviral, antifungal, deodorizing, and other applications while achieving both safety and uniformity.

[0064] The step (A) of producing a copper nanoparticle dispersion is as described above in "1. Method for producing copper nanoparticles."

[0065] In step (B), the copper nanoparticle dispersion liquid produced in step (A) is mixed with a titania nanoparticle dispersion liquid.

[0066] When copper nanoparticles (copper nanoparticle dispersion) are mixed with titania nanoparticle dispersion (photocatalyst), it is preferable to mix them with a dispersion (sol) in which titania nanoparticles are uniformly dispersed.

[0067] The ratio of titania nanoparticle dispersion (photocatalyst) to copper nanoparticles is not particularly limited, but considering transparency, colorability, etc., the ratio of titania nanoparticle dispersion (photocatalyst) to copper nanoparticles is preferably titania nanoparticles (photocatalyst):copper nanoparticles=1:0.001 to 1:0.1 by mass. [Example]

[0068] The present invention will be specifically described based on examples.

[0069] The present invention is not limited to these.

[0070] Example Example 1 To 0.0824 g of copper (II) acetylacetonate (0.2 mass % in terms of copper atom), 10 g of 2-(dimethylamino)ethanol was added as a solvent, and the mixture was heated to 120°C.

[0071] As a result, the color of the liquid changed from ultramarine to green and brown, and a transparent, dark brown dispersion of copper nanoparticles was obtained.

[0072] When this copper nanoparticle dispersion was diluted 10 times with water, a transparent, homogeneous brown solution was obtained.

[0073] When this copper nanoparticle dispersion was diluted 10 times with ethanol, a transparent, homogeneous brown solution was obtained.

[0074] This copper nanoparticle dispersion was diluted 20 times with ethanol, and this 20-fold diluted solution was spin-coated onto a silicon wafer. After baking at 500°C, SEM observation was performed. SEM observation confirmed only nanoparticles of at least 100 nm or less (Figure 1).

[0075] This copper nanoparticle dispersion was dried and the elemental composition of the outer surface was analyzed by X-ray photoelectron spectroscopy (ESCA). A peak was observed at 932.8 eV, but no peak was observed between 940 and 945 eV, indicating that it was metallic copper (Figure 2). For example, in the case of divalent copper ions, a peak is observed above 933.5 eV, and a satellite peak is observed between 940 and 945 eV.

[0076] Furthermore, crystal structure analysis using X-ray diffraction (XRD) revealed that it was metallic copper, not monovalent copper (Figure 3).

[0077] (Example 2) An experiment was carried out in the same manner as in Example 1, except that the solvent was changed to N,N-dimethylformamide and the reaction temperature was set to 126° C. In Example 2, a dark brown dispersion of copper nanoparticles was also obtained.

[0078] (Example 3) An experiment was carried out in the same manner as in Example 1, except that the solvent was changed to N-methylformamide and the reaction temperature was set to 128° C. In Example 3 as well, a dark brown dispersion of copper nanoparticles was obtained.

[0079] (Example 4) An experiment was carried out in the same manner as in Example 1, except that the solvent was changed to N-methylformamide and the reaction temperature was set to 123° C. In Example 4 as well, a dark brown dispersion of copper nanoparticles was obtained.

[0080] (Example 5) An experiment was carried out in the same manner as in Example 1, except that the solvent was changed to a mixed solvent of 1 g of 2-(dimethylamino)ethanol and 9 g of ethylene glycol and the reaction temperature was set to 127° C. In Example 5, a dark brown dispersion of copper nanoparticles was also obtained.

[0081] (Example 6) An experiment was carried out in the same manner as in Example 1, except that the solvent was changed to a mixed solvent of 1 g of 2-(diethylamino)ethanol and 9 g of ethylene glycol and the reaction temperature was set to 127° C. In Example 6, a dark brown dispersion of copper nanoparticles was also obtained.

[0082] (Example 7) An experiment was carried out in the same manner as in Example 1, except that the solvent was changed to a mixed solvent of 1 g of 2-(diethylamino)ethanol and 9 g of anisole, and the reaction temperature was set to 127° C. In Example 7, a dark brown dispersion of copper nanoparticles was also obtained.

[0083] (Example 8) An experiment was carried out in the same manner as in Example 1, except that the amount of copper (II) acetylacetonate was 0.412 g (1 mass % in terms of copper atoms) and the reaction temperature was 139° C. In Example 8, a dark brown dispersion of copper nanoparticles was also obtained.

[0084] (Example 9) An experiment was carried out in the same manner as in Example 1, except that the amount of copper (II) acetylacetonate was 0.824 g (2 mass % in terms of copper atoms) and the reaction temperature was 137° C. In Example 9, a dark brown dispersion of copper nanoparticles was also obtained.

[0085] This copper nanoparticle dispersion was diluted 20 times with ethanol, and this 20-fold diluted solution was spin-coated onto a silicon wafer. After baking at 500°C, SEM observation was performed. From the SEM observation, only particles of 100 nm or less were observed, even after baking at high temperatures.

[0086] Comparative Example Comparative Example 1: The experiment was conducted in the same manner as in Example 1, except that the solvent was changed to 10 g of ethylene glycol monomethyl ether and the reaction temperature was changed to 122 ° C. In Comparative Example 1, the reaction solution remained greenish-blue, and no copper nanoparticles were produced. After cooling, the raw material, copper (II) acetylacetonate, precipitated in a bluish-purple color.

[0087] (Comparative Example 2) An experiment was conducted in the same manner as in Example 1, except that the solvent was changed to 10 g of ethanol and the reaction temperature was changed to 122 ° C. In Comparative Example 2, the reaction solution remained blue, and no copper nanoparticles were produced. After cooling, the raw material, bluish-purple copper (II) acetylacetonate, precipitated.

[0088] (Comparative Example 3) An experiment was conducted in the same manner as in Example 1, except that the solvent was changed to 10 g of ethylene glycol. In Comparative Example 3, the liquid partially turned dark brown and copper nanoparticles were produced, but after cooling, the raw material, bluish-purple copper(II) acetylacetonate, precipitated.

[0089] (Comparative Example 4) An experiment was carried out in the same manner as in Example 1, except that the raw material was 0.076 g of copper (II) nitrate (0.2 mass % in terms of copper atoms). In Comparative Example 4, the reaction solution remained blue-green, and after cooling, the reaction solution became a mixture of blue-purple and blue precipitate, and no copper nanoparticles were produced.

[0090] (Comparative Example 5) An experiment was carried out in the same manner as in Example 1, except that the raw material was 0.063 g of copper (II) acetate (0.2 mass % in terms of copper atoms). In Comparative Example 5, the reaction solution did not change from green-blue, and after cooling, the reaction solution became a mixture of purple and white precipitates, and no copper nanoparticles were produced.

[0091] (Comparative Example 6) An experiment was carried out in the same manner as in Example 1, except that the raw material was 0.113 g of copper (II) citrate (0.2 mass % in terms of copper atoms). In Comparative Example 6, the reaction solution remained light blue, and after cooling, the reaction solution became a mixture of blue and white precipitate, and no copper nanoparticles were produced.

[0092] (Comparative Example 7) An experiment was carried out in the same manner as in Example 1, except that the raw material was 0.110 g of copper (II) ethylhexanoate (0.2 mass % in terms of copper atoms). In Comparative Example 7, the reaction solution did not change from blue-green, and after cooling, the reaction solution turned a transparent blue-purple, and no copper nanoparticles were produced.

[0093] (Comparative Example 8) An experiment was conducted in the same manner as in Example 1, except that the raw material was changed to 0.101 g of copper (II) acetoacetate (0.2 mass % in terms of copper atoms), the solvent was changed to a mixed solvent of 1 g of 2-(dimethylamino)ethanol and 9 g of ethylene glycol, and the reaction temperature was changed to 136° C. In Comparative Example 8, the color of the reaction solution did not change from deep green, and after cooling it became a cloudy ochre liquid, and a uniform copper nanoparticle dispersion was not produced.

[0094] Manufacturing of antiviral coating liquid 120 g (2 mol) of acetic acid was added to 142.1 g (0.5 mol) of titanium tetraisopropoxide, and the mixture was stirred for 60 minutes, after which 538 g of water was added. The dispersion had a titanium tetraisopropoxide concentration of 0.625 mol / L, an acetic acid concentration of 2.5 mol / L, and a pH of 2.2.

[0095] In this dispersion, a translucent precipitate was generated, but after stirring for 60 minutes, the dispersion was heated to 70° C., and the precipitate was completely dissolved. In this dispersion, the concentrations of the inorganic acid and the elements N, Cl, and S were all 0 mol / L.

[0096] The mixture was then stirred at 98°C under normal pressure (0.10 MPa) for 3 hours, cooled, and left for one month, resulting in a translucent, uniform titania sol without the use of an organic dispersant.

[0097] When this titania sol was subjected to ultrasonic dispersion, the viscosity was reduced and the transparency was increased. The heating residue (200°C) of the obtained titania sol was 5.7% by mass. The heating residue (700°C) was 5.0% by mass.

[0098] This titania sol was diluted with water to support a small amount of Ag nanoparticles, thereby preparing a dispersion of 2.0 mass % titania and 0.1 mass % Ag (titania nanoparticle dispersion).

[0099] The following liquid was prepared for 100 g of this dispersion.

[0100] Coating liquid (A) 2 g of a dispersion liquid containing 0.02 g of copper nanoparticles (1% (mass ratio) of titania as Cu atoms) synthesized in Example 8 was added.

[0101] To the coating solution (B), 0.31 g of copper acetate monohydrate was added (5% (mass ratio) of titania in terms of Cu atoms).

[0102] Coating liquid (C) 0.0063 g of copper acetate monohydrate was added (0.1% (mass ratio) of titania in terms of Cu atoms).

[0103] Coating solution (D) 0.02 g of copper nanoparticles (25 nm) was added (Cu atoms: 1% (mass ratio) of titania) Each liquid was concentrated under reduced pressure at 60°C and powdered.

[0104] With regard to the coating liquid (A), a brown powder was obtained.

[0105] For the coating solutions (B) and (C), gray powders were obtained.

[0106] Regarding coating solution (D), it turned a bright blue color during the concentration process, and a blue powder was obtained, suggesting that copper nanoparticles had dissolved in the acidic titania sol, producing divalent copper ions.

[0107] When the dispersions of coating solution (A) and coating solution (B) were spin-coated onto a 50 mm square glass at 500 pm, a translucent film was obtained. When these test pieces ((A) and (B)) were used to conduct an inactivation test of enveloped coronaviruses, the activity value in the dark was 2.9 for both, confirming sufficient activity.

[0108] Skin sensitization tests were conducted on the dispersions of coating liquid (A) and coating liquid (B), and the result was negative for coating liquid (A) and positive for coating liquid (B). Skin sensitization tests were conducted on the dispersion of coating liquid (C), and the result was positive even when the copper ion concentration was reduced to 1 / 50. [Industrial Applicability]

[0109] The method for producing copper nanoparticles of the present invention does not use reducing agents that are difficult to remove, such as metal salts, and can synthesize copper nanoparticles that have very small particle sizes, are highly active, can be coated transparently, are resistant to oxidation due to heat, oxygen, acid, etc., and are dispersible in water, hydrophilic alcohol, etc.

[0110] In the method for producing copper nanoparticles of the present invention, a copper compound having a specific structure and a solvent having a specific structure are used and stirred at a specific temperature, thereby obtaining a copper nanoparticle dispersion in a short time.

[0111] By mixing the copper nanoparticle dispersion obtained by the copper nanoparticle production method of the present invention with titania nanoparticles, a composite thereof can be obtained in a highly dispersible state.

[0112] The material containing copper nanoparticle dispersion and titania nanoparticles of the present invention is transparent and can be used as a highly active antibacterial agent, antiviral agent, antifungal agent, deodorizer, etc.

Claims

1. A method for producing copper nanoparticles, At least one compound selected from the group consisting of 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 3-(dimethylamino)-1-propanol, and 1-(dimethylamino)-2-propanol, and R ４ R ５ NCHO (Equation 2) (In formula 2, R ４ , and R ５ are the same or different and each represents a hydrogen atom or an alkyl group. In at least one organic solvent selected from the group consisting of compounds represented by A step of heating copper (II) acetylacetonate at 120°C or higher to produce copper nanoparticles; Including, The produced copper nanoparticles have a particle size of 100 nm or less. Manufacturing method.

2. 2. The method according to claim 1, wherein the compound represented by formula 2 is at least one organic solvent selected from the group consisting of N,N-dimethylformamide, N-methylformamide, and formamide.

3. The method according to claim 1 or 2, wherein the heating temperature is 120°C or higher and 150°C or lower.

4. The method according to any one of claims 1 to 3, wherein the concentration of copper(II) acetylacetonate in the total mass of the reaction solution containing the copper(II) acetylacetonate and the organic solvent is 0.1 mass% or more and 2.0 mass% or less in terms of copper atoms.

5. The method according to any one of claims 1 to 4, wherein the organic solvent further comprises at least one organic solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and anisole.

6. The method according to any one of claims 1 to 5, wherein the organic solvent has a boiling point of 75°C or higher and 200°C or lower.

7. The method according to any one of claims 1 to 6, wherein the total content of at least one organic solvent selected from the group consisting of the compound represented by formula 1 and the compound represented by formula 2 in the organic solvent is 0.01% by mass to 100% by mass.

8. A method for producing an antiviral agent, comprising: (A) At least one compound selected from the group consisting of 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 3-(dimethylamino)-1-propanol, and 1-(dimethylamino)-2-propanol, and R ４ R ５ NCHO (Equation 2) (In formula 2, R ４ , and R ５ are the same or different and each represents a hydrogen atom or an alkyl group. In at least one organic solvent selected from the group consisting of compounds represented by A step of heating copper (II) acetylacetonate at 120 ° C. or higher to produce a copper nanoparticle dispersion; (B) A step of mixing the copper nanoparticle dispersion produced in the step (A) with the titania nanoparticle dispersion. Including, The produced copper nanoparticles have a particle size of 100 nm or less, The titania nanoparticles have acetoxy groups bonded to at least some of the titanium atoms present on the surface, and when heated to 600°C using a thermogravimetric and differential thermal analyzer, they experience a mass loss of 5% by mass or more at 200°C or higher, and have a particle size of 1 nm to 10 nm. Manufacturing method.

9. 9. The method according to claim 8, wherein the compound represented by formula 2 is at least one organic solvent selected from the group consisting of N,N-dimethylformamide, N-methylformamide, and formamide.

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