Polymer Supporting Metal Nanoparticles, Composition, Article, and Method for Producing the Polymer

Abstract

To provide a metal nanoparticle-carrying polymer that is soluble in water or organic solvent and suppresses coloration in solution.MEANS FOR SOLVING THE PROBLEM: A metal nanoparticle-carrying polymer contains an uncrosslinked organic polymer backbone having a side chain containing a charging group, and metal nanoparticles supported on the uncrosslinked organic polymer backbone. The metal nanoparticles supported on the uncrosslinked organic polymer backbone have a median size (D50) of less than 5 nm.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a metal nanoparticle-supported polymer, a composition containing the polymer, an article containing the composition, and a method for producing the metal nanoparticle-supported polymer.

Background Art

[0002] It has long been known that metal ions typified by silver ions have antibacterial properties. Recently, metal ions having antiviral properties have also become known. Similar effects have also been reported in metal nanoparticles such as silver nanoparticles and platinum nanoparticles. Components having antibacterial and / or antiviral properties (hereinafter also referred to as "antibacterial and antiviral agents") using metal nanoparticles are expected to increase in the future. In addition to such applications, metal nanoparticles can be used in various applications. Conventionally, methods for supporting metal nanoparticles on organic polymers have been studied (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present inventors have studied a metal nanoparticle-supported polymer in which metal nanoparticles are supported on an organic polymer backbone. As a result, the present inventors have found that when the metal nanoparticle-supported polymer is dissolved in a solvent, coloring presumed to be caused by the metal nanoparticles is observed. Such coloring may make it difficult to develop the metal nanoparticle-supported polymer for applications that require, for example, colorless transparency.

[0005] The present disclosure aims to provide a metal nanoparticle-supported polymer that is soluble in water or an organic solvent and has suppressed coloring in solution. Another object of the present disclosure is to provide a method for producing such a metal nanoparticle-supported polymer, a composition containing the polymer, and an article containing the composition.

Means for Solving the Problems

[0006] The present inventors have conducted studies to solve the above problems. As a result, the present inventors have found that by supporting metal complex ions on a non-crosslinked organic polymer and then appropriately reducing the supported metal complex ions to form metal nanoparticles, a metal nanoparticle-supported polymer with suppressed coloring in solution can be obtained.

[0007] The metal nanoparticle-supported polymer of the present disclosure is a metal nanoparticle-supported polymer comprising a non-crosslinked organic polymer backbone having a side chain containing a charged group and metal nanoparticles supported on the non-crosslinked organic polymer backbone, wherein the median diameter (D50) of the metal nanoparticles supported on the non-crosslinked organic polymer backbone is less than 5 nm. The composition of the present disclosure contains the above metal nanoparticle-supported polymer. The article of the present disclosure includes the above composition. The method for producing a metal nanoparticle-supported polymer of the present disclosure includes: (1) a step of preparing a non-crosslinked organic polymer having a side chain containing a charged group, a metal salt, and a complexing agent; (2) a step of dissolving the non-crosslinked organic polymer, the metal salt, and the complexing agent in water to obtain a metal complex ion-supported polymer in which metal complex ions are supported on the non-crosslinked organic polymer; and (3) a step of reducing the metal complex ions in the metal complex ion-supported polymer to form metal nanoparticles having a median diameter (D50) of less than 5 nm supported on the non-crosslinked organic polymer.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide a metal nanoparticle-supported polymer that is soluble in water or an organic solvent and has suppressed coloring in solution. Further, according to the present disclosure, it is possible to provide a method for producing such a metal nanoparticle-supported polymer, a composition containing the polymer, and an article containing the composition.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] In the present disclosure, "antibacterial property" refers to the property of killing or damaging either or both of bacteria and fungi, or the property of continuously suppressing the growth and proliferation of either or both of bacteria and fungi. Examples of bacteria include staphylococcus, Escherichia coli, Salmonella, Pseudomonas aeruginosa, Vibrio cholerae, Shigella, Bacillus anthracis, Mycobacterium tuberculosis, Clostridium botulinum, Clostridium tetani, and Streptococcus. Examples of fungi (or molds) include Trichophyton, Candida, and Aspergillus.

[0011] In the present disclosure, "antiviral property" refers to the property of inactivating a virus by denaturing or damaging the proteins that constitute the capsid or envelope of the virus. Examples of the virus include norovirus, influenza virus, adenovirus, coronavirus, measles virus, rubella virus, hepatitis virus, herpes virus, and HIV.

[0012] [Polymer Supported Metal Nanoparticles] The metal nanoparticle-supported polymer of the present disclosure (hereinafter also referred to as "the polymer of the present disclosure") comprises a non-crosslinked organic polymer backbone having a side chain containing a charged group, and metal nanoparticles supported on the non-crosslinked organic polymer backbone.

[0013] In the polymer of the present disclosure, the median diameter (D50) of the metal nanoparticles supported on the non-crosslinked organic polymer backbone is less than 5 nm. Since the polymer of the present disclosure exhibits extremely low absorbance as described later, it can be suitably used for various applications.

[0014] <Uncrosslinked Organic Polymer Skeleton> The polymer of the present disclosure contains a non-crosslinked organic polymer backbone. Hereinafter, when explaining the non-crosslinked organic polymer as a molecule, it will be simply referred to as "non-crosslinked polymer", and when explaining it as a component of the polymer of the present disclosure, it will be referred to as "non-crosslinked polymer backbone".

[0015] ​The non-crosslinked polymer functions as a carrier for metal nanoparticles and metal complex ions described later. In the present disclosure, the non-crosslinked polymer means a polymer having no three-dimensional crosslinked structure, and is usually a chain polymer such as a linear polymer and a branched-chain polymer. The non-crosslinked polymer has, for example, no physical or chemical crosslinked structure in a solvent. Therefore, the polymer of the present disclosure containing a non-crosslinked polymer backbone is soluble in water or a predetermined organic solvent. Here, "soluble" means, for example, that when 1 g of the polymer is added to 100 mL of the solvent at room temperature (25°C), it does not become cloudy, precipitate, or gel. By using the polymer of the present disclosure containing a non-crosslinked polymer backbone, a transparent composition can be prepared or a transparent film can be formed.

[0016] The non-crosslinked polymer has a side chain containing a charged group. The charged group is a group that can be negatively or positively charged (ionized) in water, and is, for example, a proton-donating group (Bronsted acid) or a proton-accepting group (Bronsted base). Thereby, in water, the molecular chain of the non-crosslinked polymer is negatively or positively charged, the entanglement of the molecular chains of the non-crosslinked polymer is loosened by electrostatic repulsion, and at the same time, the charged group or the binding group described later is exposed in water. The metal nanoparticles described later are bound to the exposed charged group or binding group. The binding group may be the same as or different from the charged group.

[0017] Examples of the charged group include anionic groups (charged groups that can be negatively charged in water) such as carboxy groups and sulfo groups, and cationic groups (charged groups that can be positively charged in water) such as amino groups. Among these, anionic groups such as carboxy groups and sulfo groups are preferable, and carboxy groups are more preferable. Note that the above-mentioned charged group includes a group that is negatively or positively charged (ionized). For example, when the charged group is a carboxy group, the charged group includes a carboxylate ion.

[0018] The side chain may be the charged group itself.

[0019] The chargeable group contained in the non-crosslinked polymer is preferably only one of an anionic group or a cationic group. For example, in the case of a non-crosslinked polymer having a side chain containing a carboxy group, it is preferable that the non-crosslinked polymer does not have a side chain containing an amino group, and in the case of a non-crosslinked polymer having a side chain containing an amino group, it is preferable that the non-crosslinked polymer does not have a side chain containing a carboxy group.

[0020] The content of the chargeable group in the non-crosslinked polymer is preferably 0.1 mmol / g or more and 100 mmol / g or less, more preferably 0.5 mmol / g or more and 50 mmol / g or less, and still more preferably 1 mmol / g or more and 20 mmol / g or less. When the content of the chargeable group is within the above range, the entanglement of the molecular chains of the non-crosslinked polymer can be sufficiently loosened by electrostatic repulsion in water, and the non-crosslinked polymer can sufficiently hold the metal nanoparticles and the metal complex ions described later by the chargeable groups.

[0021] The chargeable group is preferably uniformly distributed over the entire molecular chain of the non-crosslinked polymer. When the side chains containing the chargeable groups are unevenly distributed within the molecular chain, the solubility of the non-crosslinked polymer in water may decrease or the loading amount of the metal nanoparticles may decrease.

[0022] The non-crosslinked polymer having a side chain containing a chargeable group can be obtained, for example, by homopolymerizing or copolymerizing a monomer containing a chargeable group. Examples of the non-crosslinked polymer having a side chain containing a chargeable group include vinyl polymers, polysaccharides, and proteins having a repeating structural unit containing a chargeable group. Among these, vinyl polymers having a repeating structural unit containing a chargeable group are preferable.

[0023] In the above non-crosslinked polymer, the content ratio of the repeating structural unit containing a chargeable group is preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more in all the repeating structural units. In the present disclosure, the content ratio of the above structural unit can be determined by NMR.

[0024] Examples of the vinyl polymer having a repeating structural unit containing a charged group include a homopolymer or copolymer of an ethylenically unsaturated monomer containing a charged group, and a copolymer of an ethylenically unsaturated monomer containing a charged group and an ethylenically unsaturated monomer not containing a charged group.

[0025] Examples of the ethylenically unsaturated monomer containing a charged group include carboxy group-containing monomers such as (meth)acrylic acid, crotonic acid, β-carboxyethyl (meth)acrylate, maleic acid, itaconic acid, fumaric acid, and citraconic acid, and anhydrides of unsaturated dicarboxylic acids such as maleic anhydride and itaconic anhydride; and sulfo group-containing monomers such as vinylsulfonic acid and p-styrenesulfonic acid.

[0026] Examples of the ethylenically unsaturated monomer not containing a charged group include styrenes, vinyl alkanoates, vinyl aromatic carboxylates, and (meth)acrylates.

[0027] Examples of the styrenes include styrene, methylstyrene, vinyltoluene, vinyl ethylbenzene, and vinylnaphthalene. Examples of the vinyl alkanoates include vinyl acetate, vinyl propionate, and vinyl butyrate. Examples of the vinyl aromatic carboxylates include vinyl benzoate.

[0028] Examples of (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and isopropyl (meth)acrylate; alicyclic or aromatic ring-containing (meth)acrylates such as cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and methylcyclohexyl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; and glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate.

[0029] In a copolymer of an ethylenically unsaturated monomer containing a charged group and an ethylenically unsaturated monomer not containing a charged group, the content ratio of the structural unit derived from the ethylenically unsaturated monomer containing a charged group is preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more in all repeating structural units.

[0030] Specific examples of the vinyl polymer having a repeating structural unit containing a charged group include poly(meth)acrylic acid, polymaleic acid, polyitaconic acid, polyvinylsulfonic acid, polystyrenesulfonic acid, (meth)acrylic acid-maleic acid copolymer, and (meth)acrylic acid-vinylsulfonic acid copolymer, and metal salts thereof. Examples of the metal salts include sodium salts and potassium salts. Among these, poly(meth)acrylic acid and its metal salts are preferred, and polyacrylic acid and its metal salts are more preferred.

[0031] Examples of the polysaccharide having a repeating structural unit containing a charged group include polysaccharides having a repeating structural unit containing a carboxy group, specifically, carboxymethyl cellulose, carboxyethyl cellulose, carboxymethyl starch, carboxymethyl dextran, and alginic acid, and metal salts thereof. Examples of the metal salts include sodium salts and potassium salts.

[0032] Among these, carboxymethyl cellulose, alginic acid, and metal salts thereof are preferable, and carboxymethyl cellulose, sodium carboxymethyl cellulose, alginic acid, and sodium alginate are more preferable.

[0033] Proteins have a repeating structural unit consisting of amino acid residues. Examples of amino acids having a side chain containing a charged group include acidic amino acids such as aspartic acid and glutamic acid, and basic amino acids such as lysine.

[0034] In a protein having an amino acid residue with a side chain containing a charged group, the ratio (number basis) of the amino acid residue with a side chain containing a charged group is preferably 50% or more, more preferably 60% or more, and still more preferably 70% or more among all amino acid residues.

[0035] Examples of proteins having an amino acid residue with a side chain containing a charged group include proteins of acidic amino acids such as polyaspartic acid and polyglutamic acid, and proteins of basic amino acids such as poly-L-lysine. Among these, poly-L-lysine is preferable.

[0036] Among non-crosslinked polymers having a side chain containing a charged group, poly(meth)acrylic acid is preferable, and polyacrylic acid is more preferable.

[0037] As the non-crosslinked polymer having a side chain containing a charged group, commercially available products may be used, or monomers may be polymerized and synthesized by a conventionally known method. After obtaining a non-crosslinked polymer having no charged group by polymerizing a monomer not containing a charged group, a charged group may be introduced into the polymer. For example, carboxymethyl cellulose can be obtained by substituting part or all of the hydrogen atoms of the hydroxy group in the structure of cellulose or the hydrogen atoms bonded to the oxygen atom of the hydroxymethyl group with carboxymethyl groups. Further, as the non-crosslinked polymer having a side chain containing a charged group, an extract from a natural product such as sodium alginate may be used.

[0038] The weight average molecular weight (Mw) of the non-crosslinked polymer is preferably 1,000 or more and 1,000,000 or less, more preferably 2,000 or more and 100,000 or less, and still more preferably 5,000 or more and 30,000 or less. When Mw is below the upper limit value, it is preferable because aggregation of the non-crosslinked polymer in the solvent is suppressed. In the present disclosure, Mw is the weight average molecular weight in terms of polystyrene, which is determined by gel permeation chromatography (GPC) in accordance with JIS K7252-1 (2008).

[0039] The non-crosslinked polymer skeleton constituting the polymer of the present disclosure may have a hydrophobic group bonded to the above-mentioned chargeable group. That is, the non-crosslinked polymer skeleton may have a group in which a hydrophobic group is bonded to the above-mentioned chargeable group. Thereby, the solubility of the polymer of the present disclosure in an organic solvent is increased, and the miscibility with other polymers can be improved.

[0040] In one embodiment, the hydrophobic group is preferably introduced into the non-crosslinked polymer skeleton by esterification or amidation of the above-mentioned chargeable group. Examples of the group in which the hydrophobic group is bonded to the above-mentioned chargeable group include, when the chargeable group is a carboxy group or a sulfo group, a group represented by -CONHR, -COOR, or -SO2OR, and when the chargeable group is an amino group, a group represented by -NHCOR. Here, R is a hydrophobic group.

[0041] Examples of the hydrophobic group include hydrocarbon groups such as aliphatic hydrocarbon groups, alicyclic-containing hydrocarbon groups, and aromatic ring-containing hydrocarbon groups. The number of carbon atoms of the hydrophobic group is preferably 4 or more and 18 or less. When dissolving the polymer of the present disclosure in an organic solvent having a low polarity (dielectric constant) (such as toluene or cyclohexane), it is preferable that a hydrophobic group having a large number of carbon atoms is bonded to the above-mentioned chargeable group.

[0042] Examples of the aliphatic hydrocarbon group include alkyl groups such as butyl group, hexyl group, 2-ethylhexyl group, octyl group, decyl group, hexadecyl group and octadecyl group; and alkenyl groups such as oleyl group. Examples of the alicyclic hydrocarbon group include cycloalkyl groups such as cyclohexyl group. Examples of the aromatic ring-containing hydrocarbon group include aralkyl groups such as benzyl group.

[0043] In the polymer of the present disclosure, among the above-mentioned chargeable groups, the proportion (in terms of moles) of the hydrophobic group bonded to the chargeable group is preferably 0.1% or more and 50% or less, more preferably 0.5% or more and 20% or less, and still more preferably 1% or more and 10% or less. In one embodiment, the above proportion is the proportion in which the chargeable group is esterified or amidated by the hydrophobic group. The above proportion can be measured by nuclear magnetic resonance method (NMR) or matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS).

[0044] Fig. 1 shows a schematic diagram of the polymer of the present disclosure. Fig. 1 is an example in which the non-crosslinked polymer is polyacrylic acid and the metal nanoparticles are silver nanoparticles. The metal nanoparticle-supported polymer 10 includes a non-crosslinked polymer skeleton 11 and metal nanoparticles 12 supported on the non-crosslinked polymer skeleton 11. A hydrophobic group 14 (n-octyl group) is bonded via an amide bond to a part of the plurality of chargeable groups 13 (carboxy groups) of the non-crosslinked polymer skeleton 11.

[0045] <Metal Nanoparticles> The polymer of the present disclosure includes metal nanoparticles supported on the non-crosslinked polymer skeleton. Examples of the metal nanoparticles include nanoparticles formed from noble metal elements, specifically, silver nanoparticles, gold nanoparticles, platinum nanoparticles, palladium nanoparticles and rhodium nanoparticles. These nanoparticles are preferable because they are less likely to be oxidized in air or in a solvent. Among the metal nanoparticles, silver nanoparticles are preferable because they have high antibacterial and antiviral properties.

[0046] The supported form of the metal nanoparticles on the non-crosslinked polymer backbone is not particularly limited. The metal nanoparticles are bonded, for example, to a bonding group, preferably a charged group, contained in the main chain or side chain of the non-crosslinked polymer backbone. Examples of the bonding group include a carboxy group, a sulfo group, an amino group, a thiol group, and a thioether bond. Among these, anionic groups such as a carboxy group and a sulfo group are preferable, and a carboxy group is more preferable. The anionic group can strongly bond to the metal nanoparticles by being negatively charged (ionized) in water.

[0047] In the polymer of the present disclosure, the median diameter (D50) of the metal nanoparticles supported on the non-crosslinked polymer backbone is less than 5 nm, preferably 4 nm or less, more preferably 3 nm or less, still more preferably 2 nm or less, and particularly preferably 1.5 nm or less. Metal nanoparticles with a D50 less than the upper limit value or below are considered not to cause the localized surface plasmon resonance described later. The lower limit of D50 is not particularly limited, but is, for example, 0.5 nm.

[0048] D50 is the median diameter (D50) indicating the 50% integrated value of the integrated distribution curve obtained by measuring the volume-based particle size distribution by the dynamic light scattering method (DLS). By using DLS, the particle size of the metal nanoparticles in the solvent can be measured in a state supported on the non-crosslinked polymer.

[0049] The content rate (loading rate) of the metal nanoparticles in the polymer of the present disclosure is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 65% by mass or less. If the content rate is 10% by mass or more, the effects of the metal nanoparticles (for example, antibacterial and antiviral properties) are exhibited well. If the content rate is 70% by mass or less, aggregation of the metal nanoparticle-supported polymer in the solution is suppressed, and thus a composition or film excellent in transparency can be obtained.

[0050] The content rate of the metal nanoparticles is calculated using the following calculation formula.

[0051]

Equation

[0052] In the above formula, "the mass of the metal nanoparticle-supported polymer" represents the solid content mass when the solvent is removed from the obtained metal nanoparticle-supported polymer. On the other hand, "the mass of the non-crosslinked polymer" represents the mass of the non-crosslinked polymer introduced into the reaction system in the metal complex ion-supporting step described later.

[0053] <Absorbance> In one embodiment, the metal nanoparticle-supported polymer of the present disclosure is characterized in that the absorbance in the range of a wavelength of 350 nm or more and 750 nm or less in an aqueous solution with a concentration of 0.01% by mass of the polymer is 0.100 or less. This is a significant feature compared to the case of conventional metal nanoparticle-supported polymers, which could not achieve such a low absorbance. For example, by using the polymer of the present disclosure, a substantially colorless composition or film can be obtained while containing metal nanoparticles.

[0054] The above absorbance is measured by the following procedure. The metal nanoparticle-supported polymer and pure water are mixed to prepare an aqueous solution with a concentration of 0.01% by mass of the above polymer. This aqueous solution is placed in a cell with an optical path length of 1 cm, and the absorbance in the range of a wavelength of 300 nm or more and 800 nm or less is measured under the condition of a measurement temperature of 25°C using an ultraviolet-visible spectrophotometer (for example, V-730 manufactured by JASCO Corporation). Pure water is used as the blank solution. The absorption spectrum is measured in a state where the aqueous solution substantially contains no impurities.

[0055] In one embodiment of the polymer of the present disclosure, the present inventors presume the reason for the extremely low absorbance in the above wavelength range as follows. However, the following explanation is only a presumption and does not limit the polymer of the present disclosure in any way.

[0056] Metal nanoparticles in the nanometer size range are generally known to exhibit localized surface plasmon resonance (hereinafter also referred to as "localized SPR"). Localized SPR is a phenomenon in which free electrons in metal nanoparticles absorb incident light energy and cause collective vibrations. When localized SPR occurs, a maximum absorption (hereinafter also referred to as "plasmon absorption") appears in the range of 350 nm or more and 750 nm or less. For example, silver nanoparticles strongly absorb light in the range of 400 nm or more and 500 nm or less depending on the particle size, and gold nanoparticles strongly absorb light in the range of 500 nm or more and 600 nm or less depending on the particle size.

[0057] The light absorption efficiency (molar extinction coefficient) due to localized SPR is known to be a thousand to a hundred thousand times higher than that of ordinary organic dyes. Therefore, even if only a small amount of metal nanoparticles is present in the system, the observer can recognize the color due to the metal nanoparticles. This has conventionally made it difficult to apply metal nanoparticles to applications that require transparency (for example, antibacterial and antiviral agents).

[0058] On the other hand, the polymer of the present disclosure exhibits extremely low absorbance. This is due to the fact that the metal nanoparticles contained in the polymer of the present disclosure do not cause localized SPR. The reason why the metal nanoparticles in the present disclosure do not cause localized SPR is related to the particle size of the metal nanoparticles. In the case of silver nanoparticles, it is considered that localized SPR occurs when the particle size is 5 nm or more and 100 nm or less, and localized SPR does not occur when the particle size is less than 5 nm.

[0059] For example, in the case of a polymer supporting silver nanoparticles, since the particle size of conventional silver nanoparticles is 5 nm or more, the color development due to the above-described localized SPR occurs. In the prior art, it was impossible to obtain ultrafine silver nanoparticles with a particle size of less than 5 nm in a stable state.

[0060] However, in the present disclosure, by the manufacturing method described later, a polymer supporting silver nanoparticles with a particle size of less than 5 nm can be obtained. Therefore, in the present disclosure, silver nanoparticles that do not cause localized SPR can be obtained in a stable state. It is considered that such ultrafine silver nanoparticles can exist stably only when supported on a non-crosslinked polymer. In this polymer, almost no discoloration due to the influence of light or heat is shown. Note that the above matters are the same not only for silver nanoparticles but also for the above-described metal nanoparticles.

[0061] The presence or absence of the above localized SPR greatly affects the shape of the absorption spectrum of an aqueous solution with a concentration of 0.01% by mass of the polymer supporting metal nanoparticles. Since the metal nanoparticles in the polymer of the present disclosure do not cause localized SPR, the polymer of the present disclosure exhibits a very low absorbance. Thus, the presence or absence of localized SPR can be easily judged visually, and strictly speaking, it can be judged from the absorption spectrum of a 0.01% by mass aqueous solution of the polymer supporting metal nanoparticles. The above description is merely an estimation and does not limit the polymer of the present disclosure in any way.

[0062] <Storage of Polymer Supported Metal Nanoparticles> The polymer supporting metal nanoparticles of the present disclosure is preferably stored in a state dissolved in a solvent. That is, the polymer of the present disclosure is preferably stored in a state of a solution containing the polymer. When the polymer supporting metal nanoparticles is dried and made into a powder, it may be difficult to redissolve it in a solvent.

[0063] In one embodiment, a polymer supporting metal nanoparticles in which a hydrophobic group is not bonded to the above chargeable group or the introduction amount of the hydrophobic group is small can be stored in water for a long time. In one embodiment, a polymer supporting metal nanoparticles in which a hydrophobic group is bonded to the above chargeable group or the introduction amount of the hydrophobic group is large can be stored in an organic solvent for a long time.

[0064] Examples of the solvent include water and organic solvents. Examples of the organic solvent include alcohol solvents such as methanol, ethanol, 2-propanol, and 1-butanol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; glycol solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; hydrocarbon solvents such as n-hexane, cyclohexane, benzene, toluene, and xylene; halogenated hydrocarbon solvents such as methylene chloride and chloroform; ether solvents such as tetrahydrofuran; nitrogen-containing solvents such as acetonitrile and N,N-dimethylformamide; and sulfur-containing solvents such as dimethyl sulfoxide. The solvent may be one kind or a mixed solvent of two or more kinds.

[0065] [Method for Producing Polymer Supported Metal Nanoparticles]

[0066] The metal nanoparticle-supported polymer of the present disclosure can be produced, for example, by the following production method. In one embodiment, the production method of the metal nanoparticle-supported polymer of the present disclosure (1) A step of preparing a non-crosslinked polymer having a side chain containing a chargeable group, a metal salt, and a complexing agent (hereinafter also referred to as "step (1)" or "preparation step"), (2) A step of dissolving the non-crosslinked polymer, the metal salt, and the complexing agent in water to obtain a metal complex ion-supported polymer in which metal complex ions are supported on the non-crosslinked polymer (hereinafter also referred to as "step (2)" or "metal complex ion support step"), (3) A step of reducing the metal complex ions in the metal complex ion-supported polymer to form metal nanoparticles having a median diameter (D50) of less than 5 nm supported on the non-crosslinked polymer (hereinafter also referred to as "step (3)" or "metal nanoparticle formation step") and includes (see Figure 2).

[0067] The method for producing a metal nanoparticle-supported polymer according to the present disclosure, in one embodiment, (4) a step of bonding a hydrophobic group to a charged group of the non-crosslinked polymer (hereinafter also referred to as "step (4)" or "hydrophobization step") is further included (see Figure 2).

[0068] The method for producing a metal nanoparticle-supported polymer according to the present disclosure, in one embodiment, (5) a step of isolating the metal nanoparticle-supported polymer (hereinafter also referred to as "step (5)" or "polymer isolation step") is further included.

[0069] <Step (1) (Preparation Step)> Step (1) is a step of preparing a non-crosslinked polymer having a side chain containing a charged group, a metal salt, and a complexing agent. Since the details of the non-crosslinked polymer have been described above, the description is omitted here. The metal salt and the complexing agent will be described in the following step (2).

[0070] <Step (2) (Metal Complex Ion Loading Step)> Step (2) is a step of dissolving the non-crosslinked polymer, the metal salt, and the complexing agent in water to obtain a metal complex ion-supported polymer in which metal complex ions are supported on the non-crosslinked polymer.

[0071] When the metal salt and the complexing agent are dissolved in water, metal complex ions are usually formed. When the non-crosslinked polymer coexists in this system, the metal complex ions are supported on the non-crosslinked polymer. Figure 3 shows a schematic diagram of the step of supporting metal complex ions 31 on the non-crosslinked polymer 11. By forming metal complex ions using the complexing agent, the reduction rate of metal ions can be appropriately controlled in step (3), and an increase in the particle size of the metal nanoparticles can be suppressed.

[0072] The metal salt is not particularly limited as long as it dissolves in water and ionizes. As the metal salt, salts containing the above-described noble metal elements are preferable, and examples thereof include silver salts such as silver nitrate and silver sulfate, chloroauric acid, chloroplatinic acid, palladium chloride, and rhodium chloride. Among these, silver salts are preferable, and silver nitrate is more preferable.

[0073] The complexing agent means a compound capable of forming a complex with a metal ion and is a ligand for the metal ion. Examples of the complexing agent include compounds having a functional group capable of coordinating to a metal ion. Examples of the functional group capable of coordinating to a metal ion include monovalent functional groups such as an amino group, a hydroxy group, a carboxy group, and a thiol group; and divalent functional groups such as an ether bond and a thioether bond (sulfide bond). Among these, from the viewpoint of suppressing the aggregation of the polymer in the solution well, an amino group, a hydroxy group, an ether bond, and a thioether bond (sulfide bond) are preferable.

[0074] The number of functional groups capable of coordinating to a metal ion in the complexing agent is preferably 2 or more, more preferably 2 or more and 6 or less, and still more preferably 2 or more and 4 or less. With such a number of functional groups, the complexing agent can coordinate well to the metal ion.

[0075] The molecular weight of the complexing agent is preferably 400 or less, more preferably 300 or less, still more preferably 200 or less, and even more preferably 150 or less. With such a molecular weight, the complexing agent can coordinate well to the metal ion and the resulting metal complex ion can be supported well on the non-crosslinked polymer.

[0076] As the complexing agent, specifically, ethylenediamine, 2,2'-thiodiethanol, ethanolamine, diethanolamine, diglycolamine, disodium ethylenediaminetetraacetate (EDTA·2Na), disodium iminodiacetate, and sodium citrate can be mentioned. Among these, from the viewpoint of suppressing the aggregation of the polymer in the solution well, ethylenediamine, 2,2'-thiodiethanol, ethanolamine, diethanolamine, and diglycolamine are preferable.

[0077] For example, when polyacrylic acid is used as the non-crosslinked polymer, silver nitrate is used as the metal salt, and ethylenediamine, thiodiethanol, or ethanolamine is used as the complexing agent, an example of the state of the metal complex ions supported on the non-crosslinked polymer is shown below.

[0078]

Chemical formula

[0079] For example, it is considered that the above functional group in the complexing agent and the carboxylate ion in polyacrylic acid coordinate from both sides of the silver ion, respectively. That is, a silver complex ion composed of silver ions coordinated by the complexing agent is formed, and it is considered that the carboxylate ion in polyacrylic acid coordinates to the silver complex ion. At this time, if polyacrylic acid is loosened by the electrostatic repulsion of the carboxylate ion as described above, the silver complex ion is likely to approach the carboxylate ion in polyacrylic acid, so the loading amount of the silver complex ion increases.

[0080] Specifically, step (2) preferably includes a step of preparing an aqueous solution of a non-crosslinked polymer having a side chain containing a charged group, and a step of adding a metal salt and a complexing agent to the aqueous solution.

[0081] First, dissolve the non-crosslinked polymer in water. The concentration of the non-crosslinked polymer in the aqueous solution is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass. When the concentration of the non-crosslinked polymer is below the upper limit value, the loading efficiency of the metal complex ions is good. When the concentration of the non-crosslinked polymer is above the lower limit value, the production efficiency is good.

[0082] From the viewpoint of promoting the dissolution of the non-crosslinked polymer in water, the aqueous solution may be heated as necessary. For example, the liquid temperature of the aqueous solution is preferably heated to be 50°C or more and 90°C or less, more preferably 60°C or more and 85°C or less.

[0083] In order to charge the charged groups contained in the non-crosslinked polymer in water, an acid or a base may be added to the aqueous solution of the non-crosslinked polymer as necessary to adjust the pH. For example, when the charged group is a carboxy group, when the pH of the aqueous solution is adjusted to the range of 5 or more and 9 or less, the non-crosslinked polymer tends to be loosened by electrostatic repulsion, and the loading amount of the metal complex ions tends to increase. Further, by adjusting the pH, the reduction rate in step (3), and thus the formation rate of the metal nanoparticles, can be adjusted. Examples of the pH adjuster include bases such as sodium hydroxide, potassium hydroxide, and sodium carbonate; and acids such as hydrochloric acid and nitric acid.

[0084] Next, a complexing agent and a metal salt are added to the aqueous solution of the non-crosslinked polymer. The final concentrations of the complexing agent and the metal salt in the aqueous solution are each independently preferably 1 mM or more and 1000 mM or less, more preferably 5 mM or more and 700 mM or less, still more preferably 10 mM or more and 200 mM or less.

[0085] The addition amount of the complexing agent is preferably 1-fold molar or more and 100-fold molar or less, more preferably 1-fold molar or more and 50-fold molar or less, still more preferably 1-fold molar or more and 10-fold molar or less, and particularly preferably 3-fold molar or more and 5-fold molar or less with respect to the addition amount of the metal salt. When the addition amount of the complexing agent is below the upper limit value, it is preferable that the loading amount of the metal complex ions does not decrease. When the addition amount of the complexing agent is above the lower limit value, it is preferable that the solubility of the metal salt in water increases.

[0086] From the viewpoint of promoting the loading of metal complex ions onto the non-crosslinked polymer, the aqueous solution may be heated as necessary. For example, the liquid temperature of the aqueous solution is preferably heated to 50°C or higher and 90°C or lower, more preferably 60°C or higher and 85°C or lower. When heated, the loading of the metal complex ions is usually completed within 10 minutes.

[0087] The content rate (loading rate) of the metal complex ions in the metal complex ion-loaded polymer is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 65% by mass or less. If the content rate is 10% by mass or more, a sufficient amount of metal nanoparticles can be formed in the subsequent process. If the content rate is 70% by mass or less, aggregation of the metal complex ion-loaded polymer in the solution is suppressed, and a composition or film with excellent transparency can be obtained.

[0088] The content rate of the metal complex ions is calculated using the following formula.

[0089]

Equation

[0090] In the above formula, "the mass of the metal complex ion-loaded polymer" represents the solid content mass when the solvent is removed from the obtained metal complex ion-loaded polymer. On the other hand, "the mass of the non-crosslinked polymer" represents the mass of the non-crosslinked polymer introduced into the reaction system in the metal complex ion loading step.

[0091] The aqueous solution of the metal complex ion-loaded polymer obtained in step (2) may be subjected to a purification step. By the purification step, unreacted substances and impurities can be removed. Examples of the purification method include dialysis and gel filtration chromatography.

[0092] <Step (3) (Metal Nanoparticle Formation Step)> Step (3) is a step of reducing metal complex ions in the metal complex ion-supported polymer to form metal nanoparticles with a median diameter (D50) of less than 5 nm supported on the non-crosslinked polymer. By this step, a metal nanoparticle-supported polymer in which metal nanoparticles are supported on the non-crosslinked polymer backbone is obtained. In step (3), by reducing the metal complex ions while they are still supported on the non-crosslinked polymer, metal nanoparticles with a small particle size, specifically a median diameter (D50) of less than 5 nm, can be formed. Fig. 3 shows a schematic diagram of the step in which the metal complex ions 31 supported on the non-crosslinked polymer 11 are reduced to metal nanoparticles 12.

[0093] The metal complex ions may be reduced using a reducing agent, or may be reduced by physical actions such as ultrasonic waves, light irradiation, or γ-ray irradiation without using a reducing agent, or may be reduced by using a reducing agent and physical actions in combination.

[0094] As the reducing agent, a known compound having reducibility can be used. Examples of the reducing agent include glucose, diethylenetriamine, triethylenetetramine, citric acid, ascorbic acid, sodium borohydride, hydrazine, ethanol, polyol, formaldehyde, tannic acid, and diborane.

[0095] The addition amount of the reducing agent is preferably 0.1 mol or more and 5 mol or less, more preferably 0.5 mol or more and 3 mol or less, and still more preferably 0.8 mol or more and 1.5 mol or less with respect to 1 mol of the metal salt added in step (2). It is particularly preferable to add the reducing agent in an equimolar amount with respect to the metal salt added in step (2). If the addition amount of the reducing agent is within the above range, the metal ions can be reduced to form metal nanoparticles, and an increase in their particle size can be suppressed.

[0096] The reaction temperature and reaction time in step (3) are preferably set according to the reducing agent used and the physical actions described above. In one embodiment, the reaction temperature in step (3) is, for example, 5°C or higher and 90°C or lower, preferably 10°C or higher and 85°C or lower. When reduction is carried out under mild conditions, an increase in the particle size of the metal nanoparticles can be suppressed. For example, by appropriately adjusting the reaction temperature and reaction time during reduction according to the reducing power of the reducing agent, the particle size of the formed metal nanoparticles can be controlled.

[0097] The aqueous solution of the polymer supporting metal nanoparticles obtained in step (3) may be subjected to a purification step. The purification step can remove unreacted substances and impurities. Examples of the purification method include dialysis and gel filtration chromatography.

[0098] <Step (4) (Hydrophobization Step)> The hydrophobization step is a step of hydrophobizing the charged groups contained in the polymer supporting metal nanoparticles. In one embodiment, a hydrophobic group is introduced into the charged groups contained in the polymer supporting metal nanoparticles. For example, a hydrophobic group is introduced by esterifying or amidating the above-mentioned charged groups.

[0099] Note that the polymer obtained in the hydrophobization step is also included in the polymer supporting metal nanoparticles. However, when the polymers before and after the hydrophobization step are particularly distinguished and described, the polymer obtained in the hydrophobization step is described as "hydrophobized polymer supporting metal nanoparticles". Specific examples of the hydrophobic group are as described above.

[0100] For example, an amide bond is formed by a condensation reaction between a carboxy group in a non-crosslinked polymer backbone supporting metal nanoparticles and an amine having a hydrophobic group, and the hydrophobic group is introduced into the above polymer backbone. FIG. 4 shows a schematic diagram of a step of introducing an n-octyl group into the carboxy group of polyacrylic acid supporting metal nanoparticles (converting the carboxy group into an n-octylaminocarbonyl group).

[0101] Examples of amines having a hydrophobic group include alkylamines such as n-butylamine, t-butylamine, n-hexylamine, 2-ethylhexylamine, n-octylamine, decylamine, hexadecylamine, and octadecylamine; alkenylamines such as oleylamine; amines having an aliphatic hydrocarbon group; cycloalkylamines such as cyclohexylamine; amines having an alicyclic hydrocarbon group; aralkylamines such as benzylamine; and amines having an aromatic ring-containing hydrocarbon group.

[0102] To allow the above condensation reaction to proceed under mild conditions, it is preferable to use a condensing agent. Examples of the condensing agent include carbodiimide-based condensing agents such as 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl), dicyclohexylcarbodiimide, and diisopropylcarbodiimide; triazine-based condensing agents such as 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM); and carbonate-based condensing agents such as carbonyldiimidazole. Among these, EDC·HCl and DMT-MM, which can be used in water, are preferable.

[0103] After converting the carboxy group in the non-crosslinked polymer backbone into an active ester group, an amide bond may be formed. In that case, it is preferable to use N-hydroxysuccinimide (NHS), 1-hydroxybenzotriazole (HOBT), etc. in combination with the above carbodiimide-based condensing agent.

[0104] For example, an ester bond is formed by a condensation reaction between a carboxy group in a non-crosslinked polymer backbone supporting metal nanoparticles and an alcohol having a hydrophobic group, thereby introducing the hydrophobic group into the polymer backbone. For example, an amide bond is formed by a condensation reaction between an amino group in a non-crosslinked polymer backbone supporting metal nanoparticles and a carboxylic acid having a hydrophobic group, thereby introducing the hydrophobic group into the polymer backbone.

[0105] The above condensation reaction is usually carried out in water. When the miscibility of an amine, alcohol or carboxylic acid having a hydrophobic group with water is not high, it is preferable to add a necessary amount of alcohol to water. That is, it is preferable to use a mixed solvent of water and alcohol as the reaction solvent. Examples of the alcohol include methanol and ethanol. The mixing ratio of water and alcohol is set so that the alkylamine or the like to be used can be freely miscible with the solvent. For example, octylamine is well miscible with a mixed solvent of equal volumes of water and methanol.

[0106] In the above condensation reaction, the concentration of the metal nanoparticle-supported polymer in the aqueous solution is preferably 0.1% by mass or more and 2% by mass or less, more preferably 0.5% by mass or more and 1% by mass or less. When the concentration is below the upper limit value, the condensation reaction proceeds well. When the concentration is above the lower limit value, the production efficiency is improved.

[0107] In the hydrophobization step, when the metal nanoparticle-supported polymer is hydrophobized, an emulsion (aqueous dispersion) of the metal nanoparticle-supported hydrophobized polymer is usually formed. That is, the emulsion of the metal nanoparticle-supported polymer is formed simultaneously with the introduction of the hydrophobic group into the non-crosslinked polymer skeleton. When a hydrophobic group is introduced into the metal nanoparticle-supported polymer, the solubility of the polymer in an aqueous solvent (for example, water and a mixed solvent of water and alcohol) decreases, and part or all of the metal nanoparticle-supported polymer cannot be dissolved in the aqueous solvent and becomes fine droplets and is dispersed in the aqueous solvent. In this way, an O / W type emulsion is formed.

[0108] Hereinafter, an example of hydrophobization using EDC·HCl, NHS and alkylamine will be described. EDC·HCl and NHS are added to an aqueous solution of the metal nanoparticle-supported polymer. Their final concentrations are each preferably independently 1 mM or more and 100 mM or less. The reaction temperature is preferably 20°C or more and 60°C or less, and the reaction time is preferably 1 minute or more and 30 minutes or less. Thereby, when a non-crosslinked polymer having a carboxy group is used, the carboxy group in the non-crosslinked polymer backbone constituting the metal nanoparticle-supported polymer is converted into an active ester group.

[0109] Next, an alkylamine is added to the above aqueous solution. The final concentration of the alkylamine is preferably 10 mM or more and 300 mM or less, more preferably 10 mM or more and 100 mM or less. The reaction temperature is preferably 20°C or more and 50°C or less, and the reaction time is preferably 1 minute or more and 30 minutes or less. Thereby, the active ester group in the non-crosslinked polymer backbone constituting the metal nanoparticle-supported polymer reacts with the alkylamine to form an amide bond.

[0110] <Step (5) (Polymer Isolation Step)> The polymer isolation step is a step of isolating the metal nanoparticle-supported polymer. The metal nanoparticle-supported polymer (metal nanoparticle-supported hydrophobized polymer) in the above emulsion is recovered by, for example, a known method. For example, by allowing the emulsion to stand, it can be separated into two layers: an upper solvent layer and a lower layer of the metal nanoparticle-supported polymer layer. In order to enhance the separation efficiency, centrifugation or electric field separation may be utilized. For example, after removing the upper solvent, it is preferable to dissolve the metal nanoparticle-supported polymer in the lower layer in an appropriate organic solvent and recover it. Specific examples of the organic solvent are as described above.

[0111] In one embodiment, the isolation of the polymer is carried out by the following procedure. The above emulsion is transferred to a centrifuge tube and centrifuged using a centrifuge. The centrifugal acceleration is preferably 1,000×g or more and 10,000×g or less, and the centrifugation time is preferably 1 minute or more and 30 minutes or less. Next, the supernatant is removed, and the metal nanoparticle-supported polymer remaining at the bottom of the centrifuge tube is dissolved in an organic solvent such as alcohol. If necessary, ultrasonic treatment is performed during the dissolution treatment.

[0112] [Composition] The composition of the present disclosure contains one or more of the metal nanoparticle-supported polymers of the present disclosure. In one embodiment, the composition of the present disclosure has antibacterial and antiviral properties and is preferably used for at least one of antibacterial and antiviral applications.

[0113] The content ratio of the polymer of the present disclosure in the composition of the present disclosure can be arbitrarily selected according to the use of the composition, and is 0.01% by mass or more and 70% by mass or less, preferably 0.1% by mass or more and 50% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less in one embodiment.

[0114] In one embodiment, the composition of the present disclosure contains at least one selected from water and organic solvents. For example, the polymer of the present disclosure is dissolved in at least one selected from water and organic solvents. Examples of the organic solvent include the specific examples described above.

[0115] The content ratio of the solvent in the composition of the present disclosure can be arbitrarily selected according to the use of the composition, and is 30% by mass or more and 99.5% by mass or less, preferably 50% by mass or more and 99% by mass or less, more preferably 60% by mass or more and 98% by mass or less in one embodiment.

[0116] For example, the composition of the present disclosure can be obtained by dissolving the metal nanoparticle-supported polymer of the present disclosure in at least one solvent selected from water and organic solvents. Examples of the method for dissolving the polymer of the present disclosure in a solvent include methods using a magnetic stirrer, a motor with stirring blades, a homogenizer, or an ultrasonic cleaner. In one embodiment, the composition of the present disclosure is provided in forms such as liquid, gel, and spray.

[0117] In one embodiment, the composition of the present disclosure contains one or more resins other than the polymer of the present disclosure. For example, the polymer of the present disclosure can be well mixed with the above resins. Since the polymer of the present disclosure is excellent in dispersibility in the resin, when the resin is excellent in transparency in one embodiment, the transparency of the resin can be maintained.

[0118] Examples of the resin include polyolefins such as polyethylene, polypropylene, and cyclic polyolefin; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; styrene resins such as acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, and polystyrene; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyacrylonitrile, polyamide, polyimide, polyamideimide, (meth)acrylic resin, polycarbonate, polyaryl phthalate, polysulfone, polyethersulfone, polyphenylene sulfide, polyurethane, acetal resin, cellulose resin, fluororesin, phenol resin, melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin.

[0119] In one embodiment, the polymer of the present disclosure can be used in an amount of 0.1 part by mass or more and 50 parts by mass or less, preferably 0.5 part by mass or more and 40 parts by mass or less, more preferably 1 part by mass or more and 30 parts by mass or less, based on 100 parts by mass of the above resin.

[0120] The polymer of the present disclosure and the above resin can be mixed using known mixing devices such as a Henschel mixer, V-type blender, tumbler, roll, and kneader.

[0121] In one embodiment, the composition of the present disclosure contains one or more active energy ray curable resin components. For example, the polymer of the present disclosure can be well mixed with the above active energy ray curable resin components. Since the polymer of the present disclosure has excellent dispersibility in the active energy ray curable resin component, in one embodiment, the transparency of the cured product of the active energy ray curable resin component can be maintained.

[0122] The active energy ray curable resin component is a resin component that cures upon irradiation with active energy rays. The resin component may be any of a monomer, an oligomer, and a polymer. Examples of the active energy rays include electromagnetic waves such as ultraviolet rays (UV), X-rays, and γ-rays; and charged particle beams such as electron beams (EB), α-rays, and ion beams.

[0123] As the active energy ray curable resin component, a photocurable resin component is preferable, and a (meth)acrylic photocurable resin component is more preferable. Examples of the (meth)acrylic photocurable resin component include polyfunctional (meth)acrylates [for example, (meth)acrylates having 2 to 8 polymerizable groups such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.], epoxy (meth)acrylates [polyfunctional epoxy (meth)acrylates having 2 or more (meth)acryloyl groups], polyester (meth)acrylates [polyfunctional polyester (meth)acrylates having 2 or more (meth)acryloyl groups], urethane (meth)acrylates [polyfunctional urethane (meth)acrylates having 2 or more (meth)acryloyl groups], silicone (meth)acrylates [polyfunctional silicone (meth)acrylates having 2 or more (meth)acryloyl groups], and (meth)acrylic polymers having polymerizable groups.

[0124] (Meth)acrylic polymers having a coincidence group are polymers in which a polymerizable unsaturated group is introduced into a part of the carboxyl groups of the (meth)acrylic polymer. For example, a part of the carboxyl groups of a (meth)acrylic acid-(meth)acrylic acid ester copolymer is reacted with the epoxy group of an epoxy group-containing (meth)acrylate to introduce a polymerizable group (photo-polymerizable unsaturated group) into the side chain, which may be a (meth)acrylic polymer.

[0125] In one embodiment, the polymer of the present disclosure can be used in an amount of 0.1 parts by mass or more and 50 parts by mass or less, preferably 0.5 parts by mass or more and 40 parts by mass or less, more preferably 1 part by mass or more and 30 parts by mass or less, based on 100 parts by mass of the active energy ray curable resin component.

[0126] When the composition contains a photocurable resin component, the composition preferably contains one or more photoinitiators capable of initiating a curing reaction by light irradiation. Examples of the photoinitiator include alkylphenone compounds, acetophenone compounds, benzoin compounds, acylphosphine oxide compounds, benzophenone compounds, thioxanthone compounds, and aminobenzophenone compounds. The content of the photoinitiator is preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the photocurable resin component.

[0127] Since the polymer of the present disclosure is excellent in miscibility with the resin and the active energy ray curable resin component and also excellent in dispersibility, metal nanoparticles contained in the polymer of the present disclosure can exist at a sufficient density on the surface of the film formed from the composition of the present disclosure. Thereby, in one embodiment, high immediate antibacterial and antiviral properties can be obtained.

[0128] The composition of the present disclosure may contain one or more other antibacterial and antiviral components, such as sodium hypochlorite, hypochlorous acid water, and quaternary ammonium salts, as necessary. The composition of the present disclosure may contain at least one selected from the group consisting of a dispersion stabilizer, a humectant, a thickener, a pH adjuster, and a surfactant, as necessary.

[0129] Using the compositions of the present disclosure, various molded articles such as pellets, sheets, films, plates, containers, and pipes can be formed. The compositions of the present disclosure may be applied to the surface of a substrate, such as paints and coating agents.

[0130] [Article] The articles of the present disclosure contain the compositions of the present disclosure. In one embodiment, the articles of the present disclosure have antibacterial and antiviral properties in the components formed from the compositions. Therefore, the articles of the present disclosure are preferably used for at least one of antibacterial and antiviral applications.

[0131] The articles of the present disclosure are not particularly limited as long as they contain the compositions of the present disclosure. The above articles are formed from the compositions of the present disclosure or include components (for example, surface layers, members, or parts) formed from the compositions of the present disclosure. In one embodiment, the articles of the present disclosure include a layer formed from the compositions of the present disclosure, and the layer constitutes at least a part of the surface layer of the articles of the present disclosure. In one embodiment, since the articles of the present disclosure are excellent in antibacterial and antiviral properties, they can be widely used, for example, as articles that people touch with their hands.

[0132] In one embodiment, the thickness of the layer formed from the compositions of the present disclosure is 0.05 μm or more and 200 μm or less, preferably 0.1 μm or more and 10 μm or less, more preferably 0.15 μm or more and 5 μm or less.

[0133] In the present disclosure, the antibacterial property of an article is evaluated in accordance with ISO 22196 (JIS Z2801), and the antiviral property of an article is evaluated in accordance with ISO 21702.

[0134] Examples of the above-mentioned articles include film products for protecting touch panels, face shields, handrails, buttons, switches, windows, etc.; textile products such as socks, underwear, towels, curtains, and carpets; building materials such as floor materials, wallpapers, tiles, and paints; kitchen supplies such as sponges, cutting boards, film packaging materials, brushes, and lunch boxes; bath and toilet supplies such as bath mats, brushes with toilet cases, and bottles; daily necessities such as toothbrushes, shoe insoles, masks, and antibacterial sprays; toys such as stuffed animals and building blocks; household electrical appliances such as washing machines, vacuum cleaners, and refrigerators; and automotive parts such as steering wheels, shift knobs, air cleaners, and interior materials.

[0135] This disclosure relates to, for example, the following [1] to

[17] . [1] A metal nanoparticle-supported polymer comprising a non-crosslinked organic polymer backbone having a side chain containing a charged group and metal nanoparticles supported on the non-crosslinked organic polymer backbone, wherein the median diameter (D50) of the metal nanoparticles supported on the non-crosslinked organic polymer backbone is less than 5 nm. [2] The metal nanoparticle-supported polymer according to [1] above, wherein the metal nanoparticles are bonded to the charged group. [3] The metal nanoparticle-supported polymer according to [1] or [2] above, wherein the charged group is a carboxy group. [4] The metal nanoparticle-supported polymer according to any one of [1] to [3] above, wherein a hydrophobic group is bonded to a part of the plurality of charged groups of the non-crosslinked organic polymer backbone. [5] The metal nanoparticle-supported polymer according to [4] above, wherein the hydrophobic group is a hydrocarbon group having 4 to 18 carbon atoms. [6] The metal nanoparticle-supported polymer according to any one of [1] to [5] above, wherein the metal nanoparticles are silver nanoparticles. [7] The metal nanoparticle-supported polymer according to any one of [1] to [6] above, wherein the content of the metal nanoparticles is 10% by mass or more and 70% by mass or less. [8] A composition containing the metal nanoparticle-supported polymer according to any one of [1] to [7] above. [9] The composition according to [8] above, having antibacterial and / or antiviral properties.

[10] An article containing the composition according to [8] or [9] above.

[11] A method for producing a polymer supported with metal nanoparticles, comprising: (1) a step of preparing a non-crosslinked organic polymer having a side chain containing a charged group, a metal salt, and a complexing agent; (2) a step of dissolving the non-crosslinked organic polymer, the metal salt, and the complexing agent in water to obtain a metal complex ion-supported polymer in which metal complex ions are supported on the non-crosslinked organic polymer; and (3) a step of reducing the metal complex ions in the metal complex ion-supported polymer to form metal nanoparticles having a median diameter (D50) of less than 5 nm supported on the non-crosslinked organic polymer.

[12] The method for producing a polymer supported with metal nanoparticles according to

[11] above, further comprising (4) a step of bonding a hydrophobic group to the charged group of the non-crosslinked organic polymer.

[13] The method for producing a polymer supported with metal nanoparticles according to

[12] above, wherein the hydrophobic group is a hydrocarbon group having 4 to 18 carbon atoms.

[14] In step (4), an emulsion of the hydrophobized polymer supported with metal nanoparticles is formed, and the production method further comprises (5) a step of isolating the hydrophobized polymer supported with metal nanoparticles from the emulsion. The method for producing a polymer supported with metal nanoparticles according to

[12] or

[13] above.

[15] The method for producing a polymer supported with metal nanoparticles according to any one of

[11] to

[14] above, wherein the charged group is a carboxy group.

[16] The method for producing a polymer supported with metal nanoparticles according to any one of

[11] to

[15] above, wherein the metal salt is a silver salt.

[17] The method for producing a polymer supported with metal nanoparticles according to any one of

[11] to

[16] above, wherein the complexing agent is a compound having a molecular weight of 400 or less and having at least one functional group selected from an amino group, a hydroxy group, a carboxy group, a thiol group, an ether bond, and a sulfide bond.

Examples

[0136] Hereinafter, the polymers and the like of the present disclosure will be described using specific examples. [Antibacterial Test] The antibacterial property of the aqueous solution of the polymer supported with metal nanoparticles was evaluated according to the following procedure.

[0137] The polymer (such as the polymer supported with silver nanoparticles) obtained in the example or comparative example was added to pure water to obtain 10 mL of an aqueous solution (specimen) with a polymer concentration of 0.01% by mass. Escherichia coli (NBRC 3972) used in the test was cultured with enrichment at 35 °C for 24 hours in a liquid medium. After the culture, the concentration of Escherichia coli was adjusted to 10 8 cfu / mL using sterilized normal broth medium (1 / 500 NB medium) (cfu: colony forming unit). 0.1 mL of this bacterial solution was inoculated into 10 mL of the above specimen containing the above polymer and left standing at 25 °C for 1 hour. Then, a 10-fold dilution series of the specimen was prepared using sterilized phosphate buffered saline (PBS). 1 mL was taken from each dilution series and mixed with SCDLP agar medium. After culturing this at 30 °C for 48 hours, the grown colonies were counted and converted to the number of viable bacteria. As a negative control, PBS not containing the above polymer was also tested in the same manner. Finally, the antibacterial activity value was calculated using the following formula. When the antibacterial activity value was 2.0 or more, it was determined to be effective.

[0138]

Equation

[0139] [Measurement of Absorption Spectrum and Absorbance] The polymer obtained in the example or comparative example and pure water were mixed to prepare an aqueous solution with a concentration of 0.01% by mass of the polymer. This aqueous solution was placed in a cell with an optical path length of 1 cm, and using an ultraviolet-visible spectrophotometer (V-730 manufactured by JASCO Corporation), the absorbance in the wavelength range of 300 nm or more and 800 nm or less was measured under the condition of a measurement temperature of 25 °C. Pure water was used as the blank solution. The absorption spectrum was measured in a state where the aqueous solution substantially contained no impurities.

[0140] [Measurement of Particle Size of Metal Nanoparticles] Measurement was carried out by the dynamic light scattering method (DLS) as follows. The polymer obtained in the example or comparative example was mixed with pure water to prepare a plurality of diluted aqueous solutions of the polymer. The aqueous solution concentration was selected to be within the specified range of a particle size distribution meter (NanoTrack UPA-UT manufactured by Nikkiso Co., Ltd.) used for particle size measurement, and the particle size distribution was measured under the conditions of a solvent refractive index of 1.333, a non-spherical particle shape, and a measurement temperature of 20°C.

[0141] [Silver Nanoparticle Content] The content rate of silver nanoparticles was calculated according to the above-described formula.

[0142] [Example 1] 0.6 g of polyacrylic acid (weight average molecular weight 25,000, manufactured by Fujifilm Wako Pure Chemical Corporation) was dissolved in 30 mL of water. 5 mL of 1M NaOH aqueous solution, 2 mL of thiodiethanol, and 0.85 g of silver nitrate were sequentially added thereto, and the mixture was stirred at 70 to 80°C for 5 minutes. Subsequently, 5 mL of 1M D-glucose aqueous solution was added, and the mixture was further stirred at 70 to 80°C for 15 minutes. Finally, the obtained polymer aqueous solution was enclosed in a dialysis tube and dialysis was performed in pure water. When the particle size (D50) of the silver nanoparticles was measured using DLS, it was 1 nm.

[0143] [Example 2] 0.6 g of polyacrylic acid (weight average molecular weight 25,000, manufactured by Fujifilm Wako Pure Chemical Corporation) was dissolved in 30 mL of water. 1 mL of ethylenediamine and 0.85 g of silver nitrate were added thereto, and the mixture was stirred at 70 to 80°C for 5 minutes. Subsequently, 0.54 mL of diethylenetriamine was added, and the mixture was further stirred at room temperature for 30 minutes. Finally, the obtained polymer aqueous solution was enclosed in a dialysis tube and dialysis was performed in pure water. The silver nanoparticle content rate of the obtained silver nanoparticle-supported polymer was 56.4 mass%.

[0144] [Example 3] 0.6 g of polyacrylic acid (weight average molecular weight 25,000, FUJIFILM Wako Pure Chemical Industries, Ltd.) was dissolved in 30 mL of water. 1 mL of ethylenediamine and 0.425 g of silver nitrate were added thereto, and the mixture was stirred at 70 to 80 °C for 5 minutes. Subsequently, 0.27 mL of diethylenetriamine was added, and the mixture was stirred at 70 to 80 °C for an additional 5 minutes. Finally, the obtained aqueous polymer solution was sealed in a dialysis tube and dialysis was performed in pure water.

[0145] [Examples 4 - 6] The procedure was carried out in the same manner as in Example 3, except that the amounts of silver nitrate and diethylenetriamine used were changed as shown in Table 1.

[0146] [Example 7] 0.6 g of sodium carboxymethyl cellulose (FUJIFILM Wako Pure Chemical Industries, Ltd., hereinafter also referred to as "CMC·Na") was dissolved in 30 mL of water. 2 mL of thiodiethanol and 0.85 g of silver nitrate were added thereto, and the mixture was stirred at 70 to 80 °C for 5 minutes. Subsequently, 5 mL of 1 M D-glucose aqueous solution was added, and the mixture was stirred at 70 to 80 °C for an additional 30 minutes. Finally, the obtained aqueous polymer solution was sealed in a dialysis tube and dialysis was performed in pure water.

[0147] [Comparative Example 1] The procedure was carried out in the same manner as in Example 2, except that silver nitrate was not added.

[0148] [Comparative Example 2] 0.6 g of polyacrylic acid (weight average molecular weight 25,000, FUJIFILM Wako Pure Chemical Industries, Ltd.) was dissolved in 30 mL of water. 1 mL of ethylenediamine and 0.85 g of silver nitrate were added thereto, and the mixture was stirred at 70 to 80 °C for 5 minutes. Subsequently, 5 mL of 1 M D-glucose aqueous solution was added, and the mixture was stirred at 70 to 80 °C for an additional 30 minutes. Finally, the obtained aqueous polymer solution was sealed in a dialysis tube and dialysis was performed in pure water.

[0149] [Comparative Example 3] 0.6 g of bovine bone gelatin (Fuji Film Wako Pure Chemical Industries, Ltd.) was dissolved in 30 mL of water. 2 mL of thiodiethanol and 0.21 g of silver nitrate were added thereto, and the mixture was stirred at 70 - 80 °C for 5 minutes. Subsequently, 1.25 mL of 1 M aqueous D - glucose solution and 5 mL of 1 M aqueous NaOH solution were added, and the mixture was further stirred at 70 - 80 °C for 15 minutes. Finally, the obtained aqueous polymer solution was sealed in a dialysis tube and dialysis was performed in pure water.

[0150] [Comparative Example 4] The procedure was carried out in the same manner as in Comparative Example 3, except that the amount of silver nitrate added was changed to 0.05 g and the amount of 1 M aqueous D - glucose solution added was changed to 0.31 mL.

[0151] [Results] When the absorption spectrum of the aqueous polymer solution obtained in the example was measured, no plasmon absorption due to silver nanoparticles was observed (Figure 5), and moreover, the aqueous solution exhibited excellent antibacterial properties (Table 1).

[0152] When the absorption spectrum of the aqueous polymer solution obtained in Comparative Example 1 was measured, since no silver nitrate was added, no silver nanoparticles were present, and thus no plasmon absorption was observed (Figure 6). When an antibacterial test was performed on this aqueous solution, no antibacterial property was recognized (Table 2). Although the aqueous polymer solutions obtained in Comparative Examples 2 - 4 exhibited antibacterial properties, plasmon absorption due to silver nanoparticles was observed. Therefore, the D50 of the silver nanoparticles in the polymers obtained in Comparative Examples 2 - 4 is considered to be 5 nm or more.

[0153]

Table 1

[0154]

Table 2

[0155] In Example 2, diethylenetriamine with strong reducing power was used and the reaction was carried out at 30°C or lower for 30 minutes. On the other hand, in Comparative Example 2, glucose with weak reducing power was used and the reaction was carried out at 70°C or higher for 30 minutes. Thus, by appropriately controlling the reaction temperature and reaction time during reduction according to the reducing power of the reducing agent, silver nanoparticles with no observable plasmon absorption could be formed.

[0156] In Example 1, a pH adjuster was added to the aqueous polyacrylic acid solution before adding silver nitrate, glucose with weak reducing power was used, and the reaction was carried out at 70°C or higher for 15 minutes. On the other hand, in Comparative Example 2, glucose with weak reducing power was used and the reaction was carried out at 70°C or higher for 30 minutes. Thus, even when using a reducing agent with weak reducing power, by appropriately controlling the reaction temperature, reaction time, and pH during reduction, silver nanoparticles with no observable plasmon absorption could be formed.

[0157] As described above, by appropriately adjusting the reaction temperature, reaction time, pH, etc. during reduction according to the reducing power of the reducing agent, silver nanoparticles with no observable plasmon absorption can be formed.

[0158] In Comparative Example 3, it is considered that the amount of silver complex ions supported on bovine bone gelatin is less than that on polyacrylic acid. When the amount of silver complex ions supported is small, silver nanoparticles tend to be formed in a free state in the solution. The silver nanoparticles formed in this way are considered to quickly aggregate and reach a size of 5 nm or more. Therefore, reducing silver complex ions in a state where most of the silver complex ions are supported (fixed) on the polymer is also preferable from the viewpoint of suppressing the above aggregation.

[0159] [Example 8] The silver nanoparticle-supported polymer obtained in Example 1 was hydrophobized according to the following procedure. First, 10 mL of an aqueous solution of the silver nanoparticle-supported polymer (3.1% by mass), 10 mL of pure water, and 20 mL of methanol were added. 2 mL of an aqueous solution of EDC·HCl / NHS (each 0.1 M) was added thereto, and the mixture was allowed to stand for 10 minutes. 1.5 mL of n-octylamine was added thereto, and the mixture was allowed to stand for 3 minutes. Thereby, an emulsion of the hydrophobized polymer supporting silver nanoparticles was obtained. After centrifuging this emulsion, the supernatant was removed, and the obtained solid content was dissolved in 10 mL of methanol. The solid content concentration of the obtained hydrophobized polymer supporting silver nanoparticles was 2.0% by mass.

[0160] [Example 9] A coating agent was prepared using a methanol solution of the hydrophobized polymer supporting silver nanoparticles obtained in Example 8, and the PET (polyethylene terephthalate) film was coated as follows using this coating agent.

[0161] First, a coating agent having the following composition was prepared. · Solvent: Methyl isobutyl ketone 5.046 g · Antibacterial component: 2.0% by mass methanol solution of the hydrophobized polymer supporting silver nanoparticles 0.789 mL · UV curable resin component: PET-30 (Nippon Kayaku) 0.157 g · Polymerization initiator: Omnirad184 (BASF) 0.006 g

[0162] After applying and drying the above coating agent to a PET film (Cosmo Shine (registered trademark) A4100, Toyobo), ultraviolet rays were irradiated. Thereby, a cured film having a thickness of about 200 nm and containing the hydrophobized polymer supporting silver nanoparticles was formed on the surface of the PET film.

[0163] The antibacterial property of the cured film obtained as described above was evaluated according to ISO 22196 (JIS Z2801). As a result, the antibacterial activity value was 7.4, and excellent antibacterial property was recognized. The negative control was the above PET film not coated with the above coating agent.

Explanation of symbols

[0164] 10 ··· Polymer supporting metal nanoparticles 11 ··· Uncrosslinked polymer (skeleton) 12 ··· Metal nanoparticles 13 ··· Charged group 14 ··· Hydrophobic group 31 ··· Metal complex ion

Claims

1. A non-crosslinked organic polymer backbone having a side chain containing a charged group, Metal nanoparticles supported on the non-crosslinked organic polymer backbone, and A metal nanoparticle-supported polymer comprising: The median diameter (D50) of the metal nanoparticles supported on the non-crosslinked organic polymer backbone is less than 5 nm, and A hydrophobic group is bonded to a part of the plurality of charged groups of the non-crosslinked organic polymer backbone, A metal nanoparticle-supported polymer.

2. The metal nanoparticle-supported polymer according to claim 1, wherein the hydrophobic group is a hydrocarbon group having 4 to 18 carbon atoms.

3. The metal nanoparticle-supported polymer according to claim 1 or 2, wherein the metal nanoparticles are bonded to the charged group.

4. The metal nanoparticle-supported polymer according to any one of claims 1 to 3, wherein the charged group is a carboxy group.

5. The metal nanoparticle-supported polymer according to any one of claims 1 to 4, wherein the metal nanoparticles are silver nanoparticles.

6. The metal nanoparticle-supported polymer according to any one of claims 1 to 5, wherein the content of the metal nanoparticles is 10% by mass or more and 70% by mass or less.

7. A composition containing the metal nanoparticle-supported polymer according to any one of claims 1 to 6.

8. The composition according to claim 7, having antibacterial and / or antiviral properties.

9. An article containing the composition according to claim 7 or 8.

10. (1) A step of preparing a non-crosslinked organic polymer having a side chain containing a charged group, a metal salt, and a complexing agent, (2) A step of dissolving the non-crosslinked organic polymer, the metal salt, and the complexing agent in water to obtain a metal complex ion-supported polymer in which metal complex ions are supported on the non-crosslinked organic polymer. (3) A step of reducing the metal complex ions in the metal complex ion-supported polymer to form metal nanoparticles having a median diameter (D50) of less than 5 nm supported on the non-crosslinked organic polymer. (4) A step of bonding a hydrophobic group to the charged group of the non-crosslinked organic polymer. A method for producing a metal nanoparticle-supported polymer, comprising the steps of:

11. The method for producing a metal nanoparticle-supported polymer according to claim 10, wherein the hydrophobic group is a hydrocarbon group having 4 to 18 carbon atoms.

12. In the step (4), an emulsion of the hydrophobized metal nanoparticle-supported polymer is formed, and the production method further includes (5) a step of isolating the hydrophobized metal nanoparticle-supported polymer from the emulsion. The method for producing a metal nanoparticle-supported polymer according to claim 10 or 11.

13. The method for producing a metal nanoparticle-supported polymer according to any one of claims 10 to 12, wherein the charged group is a carboxy group.

14. The method for producing a metal nanoparticle-supported polymer according to any one of claims 10 to 13, wherein the metal salt is a silver salt.

15. The method for producing a metal nanoparticle-supported polymer according to any one of claims 10 to 14, wherein the complexing agent is a compound having a molecular weight of 400 or less and having at least one functional group selected from an amino group, a hydroxy group, a carboxy group, a thiol group, an ether bond, and a thioether bond.

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