JP2019178219A - Composite particle, method for producing composite particle and antibacterial agent - Google Patents

Abstract

To provide an antibacterial composite particle that uses a polymer material that is accepted for use in the pharmaceutical and medical fields, as a base agent and has, therefore, high safety and good industrial handleability such as high flowability and can be produced easily, and a method for producing the same.SOLUTION: The surface charging properties of porous ether cellulose derivative fine particles are used, to form a composite of ether cellulose derivative fine particles with metal or metal ions in a mixed solution or mixture dispersion of the metal or metal ions.SELECTED DRAWING: None

Description

  The present invention relates to a polymer composite particle containing a metal or metal ion and a method for producing the same. Specifically, the present invention relates to polymer fine particles in which a metal is combined with an ether-based cellulose derivative and a method for producing the same.

  The polymer fine particles are fine particles made of a polymer, and generally indicate a material having a diameter of several tens of nanometers to several hundreds of micrometers. Unlike polymer molded products such as films, fibers, injection-molded products, and extrusion-molded products, polymer particles are remarkably large in specific surface area, and modified and improved various materials by taking advantage of higher-order structures under the fine particles. Often used as a secondary material.

  Major applications include cosmetic modifiers, toner additives, rheology modifiers such as paint, medical materials, diagnostic agents, additives for molded products such as automotive materials and building materials, powders for 3D printers Examples include raw materials.

  Medical materials used for trauma such as adhesive bandages and hemostatic materials are required to prevent the growth of bacteria on the part that directly touches the wound. In recent years, antibacterial fine particles using these polymer fine particles or polymer powder as a support have attracted particular attention.

  Patent Documents 1 and 2 disclose the technique of antibacterial cellulose particles or deodorizing materials using cellulose as a base material. These are intended to make a composite of a metal or metal ion exhibiting antibacterial properties and cellulose in order to give the cellulose particles antibacterial properties. In the technology of Patent Document 1, there is a technology in which zeolite supporting an antibacterial component such as silver is combined with viscose and made into a solution state cellulose for supporting an antibacterial material on cellulose, and then returned from viscose to cellulose. It is disclosed.

  Patent Document 2 discloses a cellulose particle forming technique having a deodorizing function using the viscose method, as in Patent Document 1, but antibacterial properties can be obtained by using sodium polyacrylate together with viscose. This is a technology for supporting the metal or metal ion shown. Although these methods are all cellulose particles, they have a common feature in that a third component is required to support an antibacterial metal or metal ion. That is, the base material of the particles of these disclosed technologies is not pure cellulose but a base material made of a mixture of zeolite or polyacrylic acid, and is considered to be used as a material that is particularly compatible with living bodies. In some cases, it is not always recognized, and has difficulties in application to these fields.

  As another method, technical disclosure of fine cellulose fibers having antibacterial properties has been made (Patent Document 3). This method is a method in which cellulose fibers are oxidized with an organic oxidizing agent, a part of the hydroxyl groups of cellulose are carboxylated, and metal ions having antibacterial properties are supported using the carboxyl groups. Since the carrier used in this technique is a fibrous material, a lump is easily generated, and there is a problem in dispersibility when it is made into a slurry. For example, when used as a coating material, it becomes a major obstacle. This is a highly promising technology.

  On the other hand, the present inventors have already disclosed the invention of porous ether-based cellulose particles (Patent Document 4), and this ether-based cellulose has already been approved for use as a pharmaceutical base. Have high safety.

JP-A-4-122743 JP 2003-122743 A JP 2014-70158 A International Publication No. 2017/73626

  Any of the methods described in Patent Documents 1 to 3 is a technique for supporting metal ions or metals used as antibacterial materials on cellulose processed into particles, but the base material of the obtained particles is: Since it is chemically different from cellulose itself or a composite with other polymers, safety is not necessarily guaranteed.

  The present invention is based on a polymer material that has been approved for use in the medical and medical fields, and has high safety, good industrial handling such as high fluidity, and antibacterial properties that are easy to manufacture. It is an object to provide composite particles and a method for producing the same.

As a result of intensive studies by the present inventors in order to achieve the above object, the following invention has been achieved.
That is, the present invention is characterized by the following.
[1] Composite particles comprising an ether-based cellulose derivative containing a metal or metal ion,
[2] The composite particles according to [1], wherein the average particle size is 1-1000 μm, and the linseed oil absorption is 50-1000 mL / 100 g.
[3] The composite according to [1] or [2], wherein the ether-based cellulose derivative constituting the ether-based cellulose derivative fine particles is at least one selected from ethyl cellulose, methyl cellulose, and propyl cellulose. particle,
[4] The composite particle according to any one of [1] to [3], wherein the sphericity is 80 or more,
[5] The composite particle according to any one of [1] to [4], wherein the particle size distribution index is 1 to 3.
[6] The metal or metal ion is at least one metal or metal ion selected from silver, copper, zinc, cobalt, nickel, palladium, cadmium, tin, platinum, gold, mercury, and lead. [5] The composite particle according to any one of
[7] The composite particles according to any one of [1] to [6], wherein the composite particles made of an ether-based cellulose derivative are contacted with a solvent in which a metal or a metal ion is dissolved or dispersed, and solid-liquid separation is performed. Production method,
[8] The method for producing composite particles according to [7], wherein the solvent in which the metal or metal ion is dissolved or dispersed is water and the pH is 6 or more.
[9] An antibacterial agent comprising the composite particles according to any one of [1] to [6].

  According to the present invention, an antibacterial composite material using a material having good fluidity and dispersibility making use of a true spherical porous point, which is difficult in the prior art, extremely easy to handle and highly biocompatible. Is possible.

  Hereinafter, the present invention will be described in detail.

  The ether-based cellulose derivative in the present invention is a cellulose derivative, which is derived from cellulose in which part or all of the hydroxyl groups of cellulose are etherified. Specific examples of the ether-based cellulose derivative obtained by etherifying part or all of the hydroxyl groups of the cellulose include alkyl cellulose, carboxyalkyl cellulose, and hydroxyalkyl cellulose.

  The alkyl cellulose in the present invention is one in which part or all of the hydroxyl groups of cellulose are substituted with an alkyl group such as a methyl group, an ethyl group, or a propyl group. More specifically, the number of carbon atoms is 1 to 18. Is preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and still more preferably a substituent thereof is a methyl group, Any one selected from an ethyl group, a propyl group, and a butyl group. Specific examples of the alkyl cellulose include ethyl cellulose and methyl cellulose.

  In the present invention, the term “hydroxyalkyl cellulose” refers to a cellulose in which a hydroxyl group is substituted with a hydroxyalkyl group such as a hydroxymethyl group or a hydroxyethyl group, and more specifically, a hydroxyalkyl group having 1 to 18 carbon atoms. Preferably, it is a hydroxyalkyl group having 1 to 8 carbon atoms, more preferably a hydroxyalkyl group having 1 to 6 carbon atoms, and more preferably, the substituent is a hydroxymethyl group, hydroxyethyl group And any one selected from a group, a hydroxypropyl group, and a hydroxybutyl group. Specific examples of hydroxyalkylcellulose include hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose.

  In the present invention, the carboxyalkyl cellulose is a carboxyalkyl group such as a carboxymethyl group or a carboxyethyl group, preferably a carboxyalkyl group having 1 to 18 carbon atoms, more preferably carbon. It is a carboxyalkyl group having a number of 1 to 8, and more preferably, the substituent is any one selected from a carboxymethyl group, a carboxyethyl group, a carboxypropyl group, and a carboxybutyl group. Specific examples of carboxyalkyl cellulose include carboxymethyl cellulose and carboxyethyl cellulose.

  The metal or metal ion in the present invention refers to a typical metal on the periodic table, a transition metal or an ion thereof. The metal species is not particularly limited, but alkali metals such as lithium, sodium, magnesium, potassium, calcium, alkaline earth metals, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, ruthenium, Examples include transition metals such as rhodium, palladium, silver, cadmium, indium, platinum, gold, and lead. Among these, iron, copper, zinc, platinum, gold, silver, lead and the like are preferable, zinc, platinum, gold and silver are more preferable, and silver is particularly preferable. These may be zero-valent metals or metal ions. Furthermore, these metals may be in any form such as clusters, nanoparticles, metal elements, and the valence state of the atoms is not limited.

  The composite particle in the present invention refers to a particle obtained by combining the metal or metal ion and an ether-based cellulose derivative. The term “composite” as used herein refers to a state in which a metal or metal ion and an ether-based cellulose derivative are bound to each other by ionic bond, covalent bond, hydrogen bond, van der Waals force or the like.

  At this time, the content of the metal or metal ion in the composite particles in the present invention is 1 ppb or more and 10% or less. The lower limit of the metal or metal ion content in the composite particles is preferably 10 ppb or more, more preferably 100 ppb or more, further preferably 1 ppm or more, particularly preferably 10 ppm or more, and extremely preferably 100 ppm or more, and most preferably 200 ppm or more. When the metal or metal ion content in the composite particles is such an amount, sufficient antibacterial properties can be imparted to the composite particles when a metal that exhibits antibacterial properties is used. Further, the upper limit of the metal or metal ion content in the composite particles is preferably 5% or less, more preferably 1% or less, still more preferably less than 1%, and particularly preferably 0.5%. % Or less, significantly preferably less than 0.5%, and most preferably 0.1% or less. If the content is in this range, the antibacterial properties are sufficiently exhibited, and the release of excess metal or metal ions can be avoided.

  The content of the metal or metal ion contained in the composite particles in the present invention can be determined by atomic absorption based on a calibration curve using a metal element standard aqueous solution.

  The size of the composite particles in the present invention is 1 to 1000 μm in terms of average particle diameter. The average particle diameter in the present invention refers to the number average particle diameter.

  The lower limit of the average particle diameter is preferably 5 μm or more, more preferably 10 μm or more, further preferably 30 μm or more, particularly preferably 50 μm or more, and particularly preferably 100 μm or more, and particularly preferably 100 μm. It is super, particularly preferably 150 μm or more. Further, the upper limit of the average particle diameter is preferably 800 μm or less, more preferably 600 μm or less, further preferably 500 μm or less, and particularly preferably 400 μm or less.

  When the average particle size is less than the lower limit, handleability may be reduced. If the average particle size exceeds the upper limit, the particle size distribution becomes wide, which is not preferable.

  The average particle diameter of the composite particles in the present invention is determined by observing the composite particles using a scanning electron microscope (FE-SEM, for example, a scanning electron microscope JSM-6301NF manufactured by JEOL Ltd.), and 100 composite particles. Is an arithmetic average value obtained by measuring the diameter (particle diameter).

  Specifically, in order to obtain an accurate average particle size that reflects the variation in particle size, the particle size is measured by observing at a magnification such that two or more and less than 100 composite particles appear in one image. To do. Subsequently, the number average particle diameter is calculated by obtaining the arithmetic average of 100 particle diameters according to the following formula. The magnification of such FE-SEM can be in the range of 100 to 5,000 times, although it depends on the particle size. Specifically, when the particle size of the composite particle is 1 μm or more and less than 3 μm, it is 5,000 times, when it is 3 μm or more and less than 5 μm, it is 3,000 times or more, and when it is 5 μm or more and less than 10 μm, it is 1,000 times. As described above, when it is 10 μm or more and less than 50 μm, it is 500 times or more, when it is 50 μm or more and less than 100 μm, it is 250 times or more, when it is 100 μm or more and 200 μm or less, it is 100 times or more, and when it is 200 μm or more and 1000 μm or less. In addition, when the fine particles are not in a perfect circle shape on the image (for example, in the case of an elliptical shape, or when the fine particles are irregularly gathered to form an aggregate), the longest diameter is measured as the particle diameter. .

  Note that Ri: particle diameter of each composite particle, n: number of measurements 100, Dn: average particle diameter.

  The composite particles in the present invention are characterized in that they also have internal pores inside the particles. Therefore, it is considered that the fine particles according to the embodiment of the present invention can take in and hold a metal or metal ions from the surface openings into the fine particles.

  The amount of the metal or metal ion taken up by the composite particles in the present invention is considered to correlate with the porosity of the composite particles. In the present invention, as an index of porosity, the amount of gas adsorbed per unit weight by BET or the like, or the oil absorption of linseed oil which is a pigment test method defined in Japanese Industrial Standards (refined linseed oil method: Japanese Industrial Standards) (JIS) K5101-13-1: 2004) is used as an index.

  Since the specific surface area method by BET strongly depends on the average particle diameter, in the embodiment of the present invention, the linseed oil absorption is used as an index as the porosity of the composite particles.

  The value of linseed oil absorption is a value measured according to Japanese Industrial Standard (JIS) K5101-13-1: 2004. Specifically, porous fine particles are placed on a glass plate, refined linseed oil is gradually added from a burette, and each time, refined linseed oil is kneaded into porous fine particles with a palette knife. This is repeated until the refined linseed oil and the porous fine particles are completely kneaded, and the volume of the consumed linseed oil is read from the burette with the point where the paste has become a smooth hardness as the end point. This paste is such that it can be spread without cracking or becoming crumbly and adheres lightly to the glass plate. The linseed oil absorption is indicated by the volume of linseed oil consumed per 100 g of porous fine particles.

  The composite particle of embodiment of this invention has the characteristic which shows the linseed oil absorption of 50-1000 mL / 100g. The lower limit is preferably 75 mL / 100 g or more, more preferably 100 mL / 100 g or more, still more preferably 150 mL / 100 g or more, particularly preferably 200 mL / 100 g or more, and particularly preferably 250 mL / 100 g. That's it. The upper limit is preferably 900 mL / 100 g or less, more preferably 800 mL / 100 g or less, still more preferably 700 mL / 100 g or less, particularly preferably 600 mL / 100 g or less, and particularly preferably 500 mL / 100 g or less. 100 g or less.

  If the amount of linseed oil absorbed is too small, for example less than 50 mL / 100 g, the amount of the target substance that can be taken into the inside of the fine particle will be reduced. For example, in applications where fine particles are used as an adsorbent, the required amount of fine particles will increase. Therefore, it is not preferable for practical use. On the other hand, if the amount of linseed oil absorption is too large, the bulk density of such fine particles tends to be small, and the fine particles are extremely likely to be scattered, which is not preferable in terms of the environment in which the fine particles are handled.

  The particle size distribution index (PDI), which is an index indicating the breadth of the particle size distribution of the composite particles of the present invention, is preferably 1 to 3, more preferably 1 to 2.5, and even more preferably 1. It is -2.0, Most preferably, it is 1-1.8, Most preferably, it is 1-1.6. The lower limit value of the particle size distribution index PDI is theoretically 1. The closer the particle size distribution index is to 1, the more uniform the particle size. If the particle size distribution index is larger than the above range, the particle size distribution is widened, and it is not preferable because it does not have a uniform particle size. A uniform particle size is preferable because the handling improves when composite particles are used as an additive.

  The particle size distribution index PDI of the composite particles of the present invention is calculated by the following equation using the particle size length measurement result performed when calculating the number average particle size.

  Ri: particle diameter of each composite particle, n: number of measurements 100, Dn: number average particle diameter, Dv: volume average particle diameter, PDI: particle diameter distribution index.

  The sphericity of the composite particles in the present invention is preferably 80 or more, more preferably 85 or more, still more preferably 90 or more, particularly preferably 95 or more, and particularly preferably 97 or more. A high sphericity is preferable because the fluidity, filling property, slipperiness, tactile sensation, and handleability of the material to which the present composite particles are added are improved.

  The sphericity of the composite particles in the present invention is an arithmetic average value of sphericity Si of 30 particles randomly selected by a scanning electron microscope, and average sphericity Sn calculated according to the following formula: Point to. The sphericity Si is the ratio of the minor axis ai of each individual particle to the major axis bi perpendicularly intersecting it, and is calculated according to the following formula.

  In addition, Sn: average sphericity, Si: sphericity of each composite particle, ai: minor diameter of each composite particle, bi: major diameter of each composite particle, n: 30 measurement numbers.

  The method for producing composite particles composed of an ether-based cellulose derivative containing a metal or metal ion of the present invention is not particularly limited, but porous ether-based cellulose derivative fine particles are produced by the method disclosed in Patent Document 4 already disclosed. A method in which a metal or metal ion that is desired to be composited is contained as a starting material is preferable.

  The composite particles of the present invention can be combined using the surface chargeability of the ether-based cellulose derivative particles. Usually, ether-based cellulose derivatives are considered to be neutral molecules because of their lack of ionic functional groups due to their molecular structure, but surprisingly their surfaces are actually negatively charged, especially in the region of pH 5 or higher. Shows a strong negative charge. By making use of this property, for example, it can be combined with a cationic metal ion.

  Because of this characteristic, the compound of metal or metal ion and ether-based cellulose derivative particles is made by mixing the metal or metal ion dissolved or dispersed in the solvent and the ether-based cellulose derivative particles dispersed in the solvent. It is preferable to form a composite by reaching a sufficient equilibrium based on surface charging.

  At this time, it is preferable to use a metal ion, because metal or metal ion can be expected to be compounded by electrostatic interaction during the formation of composite particles.

  When a metal dissolved or dispersed in a solvent is used, it is preferable to use a particulate metal so that the compounding with the ether-based cellulose derivative particles proceeds efficiently. At this time, the particle diameter of the metal is 1 nm or more and 10 μm or less, but the lower limit of the metal particle diameter is preferably 1 nm or more, more preferably 5 nm or more, further preferably 10 nm or more, Particularly preferably, it is 30 nm or more, and particularly preferably 50 nm or more. Further, the upper limit of the metal particles is preferably 1 μm or less, more preferably 500 nm or less, further preferably 200 nm or less, particularly preferably 100 nm or less, and particularly preferably 80 nm or less. When the particle diameter is within this range, the compounding with the ether-based cellulose derivative particles proceeds efficiently.

  In order to obtain the composite particles of the present invention, when metal ions dissolved or dispersed in a solvent are used, it is preferable that the metal salt is dissolved and combined. The metal salts at that time are nitrate, sulfate, nitrite, phosphate, chloride salt, fluoride salt, bromide salt, iodide salt, acetate salt, borate salt, chlorate salt, bromate salt. Iodate, perchlorate, perbromate, periodate, permanganate, thiocyanate, tetrafluoroborate, hexafluorophosphate and the like. From the viewpoint of complexing with ether type cellulose particles, preferably nitrate, sulfate, chloride, perchlorate, perbromate, periodate, tetrafluoroborate, hexafluorophosphate Nitrates, sulfates, and chloride salts are most preferable from the viewpoint of easy availability.

  Specific examples of preferable ones include silver nitrate, silver sulfate, silver chloride, silver tetrafluoroborate, silver hexafluorophosphate, copper nitrate, copper sulfate, copper chloride, zinc nitrate, zinc sulfate, zinc chloride, cobalt nitrate, cobalt sulfate, Examples include cobalt chloride, nickel nitrate, nickel sulfate, nickel chloride, palladium nitrate, palladium sulfate, palladium chloride, cadmium nitrate, tin nitrate, and lead nitrate.

  The solvent to be used is not particularly limited. However, since the dispersibility of metals or the solubility of metal ions is good, alcohol solvents such as methanol, ethanol and propanol, dimethyl sulfoxide, N-methylpyrrolidone, N, N- A polar solvent such as dimethylformamide and N, N-dimethylacetamide and at least one solvent selected from water, preferably at least one solvent selected from methanol, ethanol and water, Preferably it is water.

  In addition, when complexing with ether-based cellulose derivative particles using metal ions, it is preferable to use water as the medium for dissolving or dispersing the metal ions and the medium for dispersing the ether-based cellulose derivative particles. In order to effectively exhibit the charging performance of the particles, the pH is preferably 6 or more, more preferably 6.5 or more, and even more preferably 7 or more. The upper limit with preferable pH is 12, More preferably, it is 11, More preferably, it is 10. If it is this range, it can compound | combine on mild conditions and does not impair the durability of a material.

  The composite particles thus produced are then subjected to solid-liquid separation to isolate the composite particles.

  The composite particles of the present invention thus obtained are in a state where metals or metal ions are bound to each other on the surface of the particles or inside the pores by ionic bonds, covalent bonds, hydrogen bonds, van der Waals forces, etc. Included. In addition, the antibacterial property is exhibited by the effect of the metal or metal ion contained in the composite particle, and since it is particularly porous and has a large specific surface area, the contact area with the added system is also increased. Efficiently exhibits antibacterial action compared to.

  The composite particles of the present invention can be used for additives such as paints, paints, wallpaper or building materials, bandages, adhesive plasters, removers used in places where hygiene management needs to be strengthened, such as kitchens, canteens, hospitals, health centers, kindergartens, and nurseries. Used for medicines such as fungus sheets, disinfecting sprays, toothbrushes, etc., medical care, part of hygiene auxiliary members, etc.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these.

(1) Measurement of average particle diameter The average particle diameter of the ether type cellulose derivative-metal composite polymer fine particles of the present invention is determined using a scanning electron microscope (JEOL Co., Ltd. scanning electron microscope JSM-6301NF). The arithmetic average value obtained by measuring the diameter (particle diameter) of 100 fine particles such as pigments that were observed and randomly selected, that is, the number average particle diameter was obtained and used as the average particle diameter.

  Specifically, in order to obtain a number average particle size considering the variation in particle size, in a field of view such that 10 or more and less than 100 particles appear in one image obtained with a scanning electron microscope, The particle size was measured. Subsequently, the number average particle size was calculated by calculating the arithmetic average of 100 fine particles with the following formula. In addition, when the particles are not in a perfect circle shape on the image (for example, in the case of an elliptical shape or when the particles form an aggregate in which the particles are irregularly gathered), the longest diameter is measured as the particle diameter. .

Ri: particle diameter of each particle, n: number of measurement 100, Dn: number average particle diameter.

(2) Particle size distribution index The particle size distribution index PDI as an index indicating the degree of particle size distribution of the ether-based cellulose derivative-metal composite polymer fine particles is the result of measuring the particle size measured when calculating the average particle size. And calculated by the following formula.

Ri: particle diameter of each particle, n: number of measurement 100, Dn: number average particle diameter, Dv: volume average particle diameter, PDI: particle diameter distribution index.

(3) Sphericity The sphericity of the ether-based cellulose derivative-metal composite particle is an arithmetic average value of the sphericity Si of 30 particles randomly selected with a scanning electron microscope, and follows the following formula: Calculated. The sphericity Si is the ratio of the minor axis ai of each fine particle to the major axis bi perpendicular to it, and was calculated according to the following formula.

Here, Sn: average sphericity, Si: sphericity of each particle, ai: minor diameter of each particle, bi: major diameter of each particle, n: 30 measurement numbers.

(4) Linseed oil absorption The linseed oil absorption of the ether cellulose derivative and ether cellulose derivative-metal composite particles in the present invention is based on the method described in Japanese Industrial Standard (JIS) K5101-13-1: 2004. And measured.

(5) Particle surface potential measurement The particle surface potential of the ether-based cellulose derivative particles was measured using a zeta potentiometer (ELS-Z2 manufactured by Otsuka Electronics Co., Ltd.).

  After sufficiently wetting the ether-based cellulose derivative particles, the precipitated large particle diameter particles are removed, the sample concentration is 0.1% by mass, sodium chloride is added at pH 6-8, and the ion concentration is 1 mmol / L. And the zeta potential was measured.

(6) Measurement of metal content The content of metal or metal ion contained in the ether-based cellulose derivative particles was determined by calibration with a metal element standard aqueous solution using an atomic absorption method (atomic absorption spectrophotometer 240AA atomic absorption spectrophotometer). Quantitative measurement was performed based on a line (calibration curve range: 1 to 30 ppm).

(Reference Example 1)
In a 200 mL separable flask, ethyl cellulose (manufactured by Ashland, 'Aqualon (registered trademark)' EC-N50 Pharm, ethoxy group content 49.0% by mass (ethoxy group substitution degree 2.54), viscosity (80% by mass toluene / 20 Mass% ethanol solution, ethyl cellulose concentration 5 mass%, 25 ° C.) 45 mPa · s, crystallinity 2.0%) 7 mass parts, polymer (B) as polyvinylpyrrolidone (manufactured by BASF Japan Ltd., “Kollidon (registered trademark)” 'K-30, weight average molecular weight 50,000) 10 parts by mass, ethanol (manufactured by Gansu Chemical Industry Co., Ltd., first grade) 83 parts by mass as the alcohol solvent (C), and stirred at a rotating speed of 180 rpm However, after raising the temperature to 70 ° C. over 15 minutes, while maintaining the temperature at 70 ° C., the rotation speed is 180 rpm. Stirring was performed for 2 hours. Subsequently, while stirring at 180 rpm, 150 parts by mass of ion-exchanged water as a poor solvent (D) was dropped at a rate of 2.2 parts by mass / min via a liquid feed pump to obtain a suspension. . The obtained suspension was subjected to solid-liquid separation by filtration under reduced pressure, washed with 100 parts by mass of ion-exchanged water, and the solid matter separated was vacuum dried at 50 ° C. to obtain ethyl cellulose fine particles. When the obtained ethyl cellulose fine particles were observed by FE-SEM, it was surface porous. The average surface pore diameter is 1.81 μm, the average surface pore distance is 1.74 μm (0.96 times the average surface pore diameter), the linseed oil absorption is 102 mL / 100 g, the average particle diameter is 205 μm, and the sphericity is 98.1%, PDI was 1.13.

Example 1
20 g of 1% silver nitrate aqueous solution was added to 1 g of the porous ethyl cellulose particles (average particle size 205 μm) synthesized in Reference Example 1, and the mixture was stirred at room temperature for 4 hours and allowed to stand for 16 hours to contain silver. At this time, the pH of the mixed solution was 6.5. The obtained solid content was filtered, washed with 200 ml of ion-exchanged water, and heated and vacuum dried at 60 ° C. for 20 hours to obtain ethyl cellulose particles combined with silver. The average particle diameter of the ethyl cellulose composite particles combined with silver was 205 μm, the particle diameter distribution index was 1.15, the sphericity was 98.0, the oil absorption of linseed oil was 110 ml / 100 g, and the metal ion content (silver) was 350 ppm.

(Example 2)
20 g of 0.1% aqueous silver nitrate solution was added to 1 g of the porous ethyl cellulose particles (average particle size 205 μm) synthesized in Reference Example 1, and the mixture was stirred at room temperature for 4 hours and allowed to stand for 16 hours to contain silver. . At this time, the pH of the mixed solution was 6.7. The obtained solid content was filtered, washed with 200 ml of ion-exchanged water, and heated and vacuum dried at 60 ° C. for 20 hours to obtain ethyl cellulose particles combined with silver. The average particle size of the ethylcellulose composite particles combined with silver was 205 μm, the particle size distribution index was 1.20, the sphericity was 97.8, the oil absorption of linseed oil was 101 ml / 100 g, and the metal ion content (silver) was 260 ppm.

Claims (9)

Composite particles comprising an ether-based cellulose derivative containing a metal or metal ion. 2. The composite particle according to claim 1, wherein the average particle size is 1-1000 μm and the linseed oil absorption is 50-1000 mL / 100 g. The composite particles according to claim 1 or 2, wherein the ether-based cellulose derivative constituting the ether-based cellulose derivative fine particles is at least one selected from ethyl cellulose, methyl cellulose, and propyl cellulose. The composite particle according to any one of claims 1 to 3, wherein the sphericity is 80 or more. The composite particle according to any one of claims 1 to 4, wherein the particle size distribution index is 1 to 3. The metal or metal ion is at least one metal or metal ion selected from silver, copper, zinc, cobalt, nickel, palladium, cadmium, tin, platinum, gold, mercury, and lead. 2. Composite particles according to item 1. The method for producing composite particles according to any one of claims 1 to 6, wherein particles comprising an ether-based cellulose derivative are brought into contact with a solvent in which a metal or metal ion is dissolved or dispersed, and solid-liquid separation is performed. The method for producing composite particles according to claim 7, wherein the solvent in which the metal or metal ion is dissolved or dispersed is water and the pH is 6 or more. An antibacterial agent comprising the composite particles according to claim 1.