JP5369310B2 - Nanoparticle body and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nanoparticle body which has superior dispersibility to both of a polar organic solvent and a non-polar organic solvent. <P>SOLUTION: The method for producing the nanoparticle body includes coating the surface of the nanoparticle of a metal or a metal oxide with a phosphate-based surface active agent expressed by chemical formula (1), (wherein R<SP>1</SP>represents a saturated or unsaturated hydrocarbon group having a straight chain or branched chain of 1-3 carbon atoms; R<SP>2</SP>represents an alkyl group having 10-16 carbon atoms; n is an integer of 8-16; and m+k=3, m=1 or 2 and k=1 or 2). The nanoparticle of the metal or the metal oxide is a nanoparticle of silver, titanium oxide or iron oxide. The nanoparticle body has a hydrophilic group having an affinity to the polar organic solvent and a hydrophobic group having an affinity to the non-polar organic solvent, on the surface of the particle. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a nanoparticle body and a method for producing the same, a nanoparticle dispersion in which the nanoparticle body is dispersed, and a method for producing a composite material including the nanoparticles.

  Nanoparticles are used in a wide range of fields such as pharmaceuticals, optical materials, pigments, catalysts, and electronic materials. In this application, a nanoparticle means the particle | grains whose average particle diameter is nanosize (1 nm or more and 100 nm or less). When referring to only particles having an average particle diameter of less than 10 nm among nanoparticles, it is referred to as a single nanoparticle. In particular, single nanoparticles of metal oxide with a particle size of several nanometers exhibit unique electromagnetic and optical properties, and these materials are dispersed at high density in a resin, thereby enabling new materials such as high-density recording media and optical elements. Development is expected. As metal oxide nanoparticles, nanoparticles such as titanium oxide, zirconium oxide, iron oxide, cerium oxide, zinc oxide, and indium oxide are well known. Titanium oxide nanoparticles have properties such as high transparency in the visible range, and are used in optical filters, lenses, paints, cosmetics, and the like. Iron oxide nanoparticles are used for electromagnetic wave absorber materials and the like, and silver nanoparticles are used for antibacterial materials and the like.

  Such excellent performance of the nanoparticles is considered to be more sufficiently exhibited as the uniformity of dispersion in the base material is higher. However, the nanoparticles tend to aggregate, and the higher the concentration of nanoparticles in the dispersion, the easier it is to aggregate.

  When the metal oxide nanoparticles are dispersed in the resin, it is first necessary to uniformly disperse the nanoparticles in the resin solvent. Conventionally, a method for preparing functional nanoparticles coated with an organic substance such as a fatty acid by a reverse micelle method or a pyrolysis method of an organometallic complex is known (see Non-Patent Document 1, Non-Patent Document 2, and Patent Document 1). ). In any case, the obtained nanoparticles could be completely uniformly dispersed up to the primary particles in a nonpolar solvent such as hexane.

P.A.Dresco et al., "Langmuir", Volume 15, p. 1945-951, 1999 T. Hyeon et al., "Journal of the American Chemical Society", 123, p. 12798-12801, 2001

Japanese Patent Laying-Open No. 2008-69046 (paragraph 0014)

  However, in the adjustment methods described in Non-Patent Document 1 and Non-Patent Document 2, it cannot be dispersed in a polar solvent such as methanol, and the solvent in which the obtained nanoparticles are completely dispersed is limited to a specific solvent. There was a problem. In addition, there is a problem that the use is limited because the dispersible solvent is limited.

  Furthermore, even if the nanoparticles can be dispersed with a specific solvent, if the nanoparticles in the dispersion are made into a dry powder, it will aggregate and it will be difficult to redisperse in the solvent. There was a problem that could not be produced.

  The present invention has been made in view of such conventional problems. The first object of the present invention is to provide a nanoparticle having excellent dispersibility in both polar and nonpolar organic solvents.

  In addition, a second object of the present invention is to provide a nanoparticle dispersion having excellent dispersion uniformity of nanoparticles in the dispersion.

  A third object of the present invention is to provide a method for producing a composite material having excellent dispersion uniformity of nanoparticles in a substrate.

In the first aspect of the present invention, in order to achieve the first object, a metal or metal oxide nanoparticle is represented by the following chemical formula (1).
(Wherein, R ¹ is a hydrocarbon group of a saturated or unsaturated straight-chain or branched-chain having 1 to 3 carbon atoms, ^{R 2} is an alkyl group having 10 to 16 carbon atoms, n = 8 to 16 integer, m + k = 3 and m = 1 or 2, k = 1 or 2.)
A method for producing a nanoparticle body is provided, wherein the surface is coated with a phosphate-based surfactant represented by the formula: According to the 1st aspect of this invention, since the surface of a nanoparticle is covered with this surfactant, it is excellent in the dispersibility also in a polar organic solvent and a nonpolar organic solvent. Examples of R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a vinyl group, an allyl group, a 1-propenyl group, an isopropenyl group, an ethynyl group, and a propargyl group. R ¹ is preferably an allyl group. Regarding the surfactant of the above chemical formula (1), R ² is preferably an alkyl group having 10 or 12 carbon atoms, or an alkyl group having 14 or 16 carbon atoms. Among them, in terms of obtaining a nanoparticle body that can realize high dispersibility even with a small amount of surfactant, and in terms of high transparency when the obtained nanoparticle body is dispersed in various organic solvents, R ² is preferably an alkyl group having 10 or 12 carbon atoms, and particularly preferably n = 12.

  The phosphoric acid surfactant represented by the chemical formula (1) is, for example, a polyoxyethylene alkyl (alkenyl, alkynyl) ether and a long-chain α-olefin oxide condensed with a phosphoric acid ester using a known method. Can be easily obtained.

  In the above-described method for producing a nanoparticle body, the metal or metal oxide nanoparticles are preferably silver, titanium oxide, or iron oxide nanoparticles.

  The metal or metal oxide nanoparticles are preferably titanium oxide nanoparticles, and it is preferable to include a mixing step in which the aqueous solution containing the surfactant is mixed with the aqueous solution containing the nanoparticles. More preferably, in the mixing step, an aqueous solution containing the surfactant is quickly added to the diluted aqueous solution while stirring, and the stirring is further performed. Moreover, it is preferable to include the drying process which dries the particle | grains collect | recovered after mixing.

  In the mixing step, the amount of the surfactant is preferably 1 mmol or more and 3 mmol or less with respect to 1 g of titanium oxide.

  Moreover, it is preferable that the said nanoparticle is a single nanoparticle with an average particle diameter of 8 nm or less.

  Alternatively, the metal or metal oxide nanoparticles are iron oxide nanoparticles, and the surfactant is mixed in an aqueous solution in which an aqueous iron hydroxide solution is heated to produce iron oxide in the aqueous solution It is preferable to contain. Moreover, it is preferable to collect the precipitate produced in the mixed liquid with a magnet and to dry it into a powder.

  Alternatively, it is preferable that the metal or metal oxide nanoparticles include silver nanoparticles, and a mixing step of mixing an aqueous solution containing the surfactant and the reducing agent in an aqueous silver nitrate solution. It is preferable to add toluene to the mixed liquid to extract particles in the organic layer, collect the organic layer, evaporate the solvent to dryness, and form a powder.

In order to achieve the first object, the second aspect of the present invention includes a metal or metal oxide nanoparticle having the following chemical formula (1):
(Wherein, R ¹ is a hydrocarbon group of a saturated or unsaturated straight-chain or branched-chain having 1 to 3 carbon atoms, ^{R 2} is an alkyl group having 10 to 16 carbon atoms, n = 8 to 16 integer, m + k = 3 and m = 1 or 2, k = 1 or 2.)
A nanoparticle body characterized by being a powder having a surface coated with a phosphoric acid surfactant as shown in FIG. According to the second aspect of the present invention, since the surface of the nanoparticle is covered with both a hydrophobic group and a hydrophilic group, it can be dispersed in a polar organic solvent or a nonpolar organic solvent. Examples of R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a vinyl group, an allyl group, a 1-propenyl group, an isopropenyl group, an ethynyl group, and a propargyl group. R ¹ is preferably an allyl group. Regarding the surfactant of the above chemical formula (1), R ² is preferably an alkyl group having 10 or 12 carbon atoms, or an alkyl group having 14 or 16 carbon atoms. In terms of high transparency when dispersed in various organic solvents, the surfactant of the above chemical formula (1) is an alkyl group having 10 or 12 carbon atoms, or 14 or 16 carbon atoms for R ^2. Are preferred. Among these, R ² is preferably an alkyl group having 10 or 12 carbon atoms, and n is particularly preferably n = 12.

  In the above-described nanoparticle body, the metal or metal oxide nanoparticles are preferably titanium oxide, iron oxide, or silver nanoparticles.

  The metal or metal oxide nanoparticles are preferably titanium oxide nanoparticles and single nanoparticles having an average particle diameter of 8 nm or less.

  Moreover, it is preferable to have a hydrophilic group having an affinity for a polar organic solvent and a hydrophobic group having an affinity for a nonpolar organic solvent on the particle surface. From the viewpoint of dispersibility, it is preferable that the hydrophilic group includes a long-chain ethylene oxide group and the hydrophobic group includes a long-chain alkyl group. In particular, it is more preferable that the hydrophilic group includes a linear ethylene oxide group having 8 to 16 carbon atoms, and the hydrophobic group includes a long chain alkyl group having 10 to 16 carbon atoms. More preferably, the group and the hydrophobic group are branched in one molecule, and the branch point is a carbon atom ester-bonded to a phosphate group bonded to the surface of the nanoparticle.

  Moreover, it is preferable to disperse | distribute with an average aggregated particle diameter below 200 nm with respect to any of a nonpolar organic solvent and a polar organic solvent. It is more preferable that the average aggregate particle diameter by the dynamic light scattering method is dispersed at 30 nm or less for both the nonpolar organic solvent and the polar organic solvent. Moreover, it is preferable that it is transparent even if it disperse | distributes to any of a nonpolar organic solvent and a polar solvent.

  Moreover, the 3rd aspect of this invention is a dispersion | distribution process which disperse | distributes the nanoparticle body of the above-mentioned 2nd aspect of this invention in a nonpolar organic solvent or a polar organic solvent, in order to achieve the said 2nd objective. A method for producing a nanoparticle dispersion, comprising: According to the third aspect of the present invention, the nanoparticle dispersed in the solvent is a nanoparticle body with very little aggregation and high dispersibility regardless of the polarity of the organic solvent. By dispersing in an organic solvent, a dispersion in which nanoparticles are uniformly dispersed can be obtained. The dispersing step is preferably a step of dispersing the nanoparticle body while irradiating the solvent with ultrasonic waves. Since it is dispersed while preventing aggregation, a more uniform dispersion can be obtained.

  Moreover, in order to achieve the second object, the fourth aspect of the present invention contains the above-described nanoparticle body of the second aspect of the present invention and a nonpolar organic solvent or a polar organic solvent. A nanoparticle dispersion is provided. According to the fourth aspect of the present invention, the dispersion in the organic solvent is a nanoparticle body with extremely low aggregation and high dispersibility regardless of the polarity of the organic solvent. High dispersion uniformity of nanoparticles.

  Moreover, it is preferable that the said nanoparticle body is an average aggregate particle diameter of 200 nm or less in a dispersion. Furthermore, the nanoparticle body preferably has an average aggregate particle diameter of 30 nm or less in the dispersion. Furthermore, it is preferable to have transparency.

  In the above nanoparticle dispersion, the organic solvent is preferably ethanol, methyl methacrylate, toluene, or tetrahydrofuran.

  In addition, the fifth aspect of the present invention is cured by adding a resin solution to the above-described nanoparticle dispersion of the fourth aspect of the present invention and evaporating the solvent in order to achieve the third object. A method for producing a composite material is provided.

  According to the method for producing a nanoparticle body of the first aspect of the present invention or the nanoparticle body of the second aspect of the present invention, the dispersibility is excellent in both a polar organic solvent and a nonpolar organic solvent.

  Moreover, according to the nanoparticle dispersion manufacturing method of the 3rd aspect of this invention, or the nanoparticle dispersion of the 4th aspect of this invention, it is excellent in the dispersion uniformity of the nanoparticle in a dispersion.

  Moreover, according to the method for producing a composite material of the fifth aspect of the present invention, the composite material is excellent in dispersion uniformity of nanoparticles in the substrate.

It is a preparation flowchart of Example 1A of the nanoparticle body of this invention, and Example 1Aa of the nanoparticle dispersion of this invention. It is a figure which shows the state in each preparation step of Example 1Aa of the nanoparticle dispersion of this invention, and Example 1Aa of the nanoparticle dispersion of this invention. It is a figure which shows the FT-IR spectrum of Example 1A of Example 1A of this invention, Example 1A ', Example 1A' ', Comparative example 1X, and surfactant P12-10. It is a figure which shows the FT-IR spectrum of Example 1B of Example 1B of this invention, Example 1B ', Example 1B ", Comparative example 1X, and surfactant P12-14. It is a figure which shows the FT-IR spectrum of Example 1C, Example 1C ', Example 1C ", Comparative Example 1X, and surfactant P8-10 of the nanoparticle body of this invention. It is a figure which shows FT-IR spectrum of Example 1D, Example 1D ′, Example 1D ″, Comparative Example 1X and surfactant P16-10 of the nanoparticle body of the present invention. It is a figure which shows the FT-IR spectrum of the comparative example 2S of the nanoparticle body of this invention, comparative example 2S ', comparative example 2S ", comparative example 1X, and surfactant S10. It is a figure which shows the FT-IR spectrum of the comparative example 3T of the nanoparticle body of this invention, comparative example 3T ', comparative example 3T ", comparative example 1X, and surfactant S0. It is a figure which shows the measurement result by Example 1 Aa-d of Example 1Aa-d, Example 1A'a-d, and Example 1A''a-d of the nanoparticle dispersion by the dynamic light-scattering method. It is a figure which shows the measurement result by the dynamic light-scattering method of Example 1Ba-d, Example 1B'a-d, and Example 1B "a-d of the nanoparticle dispersion of this invention. It is a figure which shows the measurement result by the dynamic light-scattering method of Example 1Ca-d, Example 1C'a-d, and Example 1C''a-d of the nanoparticle dispersion of invention. It is a figure which shows the measurement result by the dynamic light-scattering method of Example 1Da-d, Example 1D'a-d, and Example 1D''a-d of the nanoparticle dispersion of this invention. It is a figure which shows the measurement result by the dynamic light-scattering method immediately after dispersion | distribution about Example 1D "a-d of the nanoparticle dispersion of this invention, and several days after. It is a figure which shows the measurement result by the dynamic light-scattering method of Comparative Example 2Sa-d, Comparative Example 2S'a-d, and Comparative Example 2S "a-d of the nanoparticle dispersion of this invention. It is a figure which shows the measurement result by the dynamic light-scattering method of Comparative Example 3Ta-d, Comparative Example 3T'a-d, and Comparative Example 3T "a-d of the nanoparticle dispersion of this invention. It is a figure which shows the transparency observation result of Example 1Aa-d and Example 1A'a-d of the nanoparticle dispersion of this invention. The transparency observation results of Examples 1A ″ a to d, Example 1B ″ a to d, Example 1C ″ a to d, and Example 1D ″ a to d of the nanoparticle dispersion of the present invention are shown. FIG. It is a figure which shows the transparency observation result of Example 2Aa-d of the nanoparticle dispersion of this invention. It is a figure which shows the transparency observation result of Example 3Aa-d of the nanoparticle dispersion of this invention. It is a figure which shows the transparency observation result of Comparative Example 2Sa-d, Comparative Example 2S'a-d, and Comparative Example 2S "a-d of the nanoparticle dispersion of this invention. It is a figure which shows the transparency observation result of Comparative Example 3Ta-d, Comparative Example 3T'a-d, and Comparative Example 3T "a-d of the nanoparticle dispersion of this invention. It is a particle size distribution figure of Example 1A'a-d of the nanoparticle dispersion of this invention. It is a figure which shows the transparency observation result of Example 1 A'dF of the composite material of this invention.

  When the present inventors act on a metal oxide or a metal nanoparticle with a specific anionic phosphate surfactant having both a hydrophobic group and a hydrophilic group, the particle surface is coated with the surfactant. Moreover, it discovered that a nanoparticle body could be obtained. Further, such nanoparticle bodies can be easily dispersed in a wide range of solvents from nonpolar solvents to polar solvents, and the average aggregate particle diameter is extremely small, and the nanoparticle dispersion has excellent transparency and dispersion stability. And the present invention has been completed.

  BEST MODE FOR CARRYING OUT THE INVENTION The best embodiment of the present invention is a nanoparticle body in which a surface of a metal or metal oxide nanoparticle is coated with a phosphate-based surfactant represented by the above chemical formula (1), a method for producing the nanoparticle body, and the nanoparticle A nanoparticle dispersion in which a body is dispersed in a nonpolar organic solvent or a polar organic solvent, and a method for producing the nanoparticle dispersion.

(Nanoparticles)
The nanoparticles are nanoparticles of metals or oxides thereof and are not particularly limited as long as they form a complex with phosphoric acid, but are preferably transition metals. Examples of the metal or oxide thereof include silver, titanium oxide, iron oxide, zirconium oxide, iron oxide, and zinc oxide. From the viewpoint of transparency, titanium oxide, iron oxide, and silver are preferable. Whether dispersed in a polar organic solvent or a nonpolar organic solvent, a dispersion with high dispersion uniformity and high transparency can be obtained. Of these, titanium oxide is more preferable from the viewpoint of little coloring.

  The primary particle diameter of the nanoparticles is preferably 100 nm or less, and more preferably 8 nm or less. When the primary particle diameter exceeds 100 nm, dispersion becomes difficult. When dispersed in an organic solvent, the resulting nanoparticle body having an average particle diameter of 8 nm or less can be dispersed at the primary particle level regardless of the polarity of the solvent, and the nanoparticle body can be redispersed. The nanoparticle dispersion is highly uniform because the particles are uniformly dispersed. The particle size should be small, and the lower limit is not limited as far as technically possible.

  The crystal structure of the nanoparticle is not limited, but a relatively small primary particle diameter is superior in terms of dispersibility. Therefore, for example, titanium oxide is preferably an anatase type that can realize a particle diameter of 8 nm or less.

  In order to uniformly modify the nano-level particles, for example, in the case of titanium oxide, it is preferable to use a titanium oxide sol in which titanium oxide nanoparticles are dispersed in water to form a sol. In the case of iron oxide, a mixed aqueous solution of iron sulfate hydrate and iron chloride hydrate is preferably used as a starting material, and in the case of silver, an aqueous silver nitrate solution is preferably used as a starting material. The concentration of the metal or metal oxide in the starting material is not limited. For example, it may be as thin as 5 wt% or as thick as 30 wt%.

(Surfactant)
As the surfactant, a surfactant represented by the above chemical formula (1) is preferable. In the present invention, such a surfactant serves as a surface coating agent for coating the surface of the particles. Since the surface of the nanoparticles is covered with such a surfactant, it can be dispersed in a polar organic solvent or a non-polar organic solvent and has excellent dispersibility. The surfactant is an anionic surfactant, and is a phosphate surfactant having both a hydrophobic group and a hydrophilic group. The surfactant has a hydrophobic alkyl group and a hydrophilic property from the phosphate group bonded to the particle surface. Since it is close to branching with ethylene oxide groups, the hydrophobic and hydrophilic groups cover the surface of the nanoparticles in a well-balanced manner, so the resulting nanoparticle bodies can be either polar or nonpolar organic solvents. High dispersibility. Whether the resulting nanoparticle body is dispersed in a polar organic solvent or a nonpolar organic solvent, the dispersion is highly transparent. Therefore, the obtained nanoparticle body can be used in fields where the conventional nanoparticle body cannot be used or cannot fully function.

In the chemical formula (1), R ² is an alkyl group having 10 to 16 carbon atoms and an integer of n = 8 to 16, but R ² is an alkyl group having 10 or 12 carbon atoms, or 14 or 14 carbon atoms. Sixteen alkyl groups are preferred. R ¹ is a straight-chain or branched saturated or unsaturated hydrocarbon group having 1 to 3 carbon atoms, and R ¹ is preferably an allyl group. Among them, in terms of obtaining a nanoparticle body that can realize high dispersibility even with a small amount of surfactant, and in terms of high transparency when the obtained nanoparticle body is dispersed in various organic solvents, In the surfactant represented by the chemical formula (1), R ² is preferably an alkyl group having 10 or 12 carbon atoms, and n is particularly preferably n = 12. The resulting nanoparticle bodies can be very well dispersed at the primary particle level in both polar and non-polar organic solvents. The choice of solvent is widened, it is very convenient and can be used in a wide range of fields.

  It is more preferable to branch into a hydrophobic group (long-chain alkyl chain in the chemical formula (1)) and a hydrophilic group (ethylene oxide chain) near the group bonded to the particles (the phosphoric acid group in the chemical formula (1)). .

(Nanoparticles)
The particles coated with a surfactant are preferably provided on the particle surface with a hydrophilic group having an affinity for a polar organic solvent and a hydrophobic group having an affinity for a nonpolar organic solvent. Since it has both a hydrophilic group that enables dispersion in polar organic solvents and a hydrophobic group that enables dispersion in nonpolar organic solvents, aggregates are formed during dispersion in both polar and nonpolar organic solvents. High dispersibility can be exhibited. From the viewpoint of dispersibility, it is preferable that the hydrophilic group includes a long-chain ethylene oxide group and the hydrophobic group includes a long-chain alkyl group. In particular, it is more preferable that the hydrophilic group includes a polyoxyethylene group having an n number of 8 to 16, the hydrophobic group includes a long chain alkyl group having a carbon number of 10 to 16, and the hydrophilic group. It is further preferable that the hydrophobic group is branched in one molecule, and the branch point is a carbon atom ester-bonded to a phosphate group bonded to the surface of the nanoparticle.

  It is preferable that the average aggregated particle diameter is dispersed with a thickness of 200 nm or less with respect to both the nonpolar organic solvent and the polar organic solvent. Regardless of the solvent, the particles disperse as fine particles without agglomeration. Therefore, the nanoparticle dispersion obtained by dispersing the nanoparticle body has an average aggregate particle diameter of 200 nm or less in the dispersion. Thus, the uniformity of the particles in the dispersion is increased. It is more preferable to disperse with a non-polar organic solvent and a polar organic solvent at an average aggregated particle size of 30 nm or less. Since the dispersion is obtained at the primary particle level, the obtained nanoparticle dispersion becomes a dispersion in which the nanoparticle body has an average aggregate particle diameter of 30 nm or less in the dispersion, and thus the uniformity of the particles in the dispersion is further increased. Get higher. Moreover, it is preferable that it is transparent even if it disperse | distributes to any of a nonpolar organic solvent and a polar solvent. The obtained nanoparticle dispersion has transparency regardless of the polarity of the organic solvent, and thus the application fields such as optical materials and cosmetics are widened. Furthermore, it is more preferable that transparency is high. It can be applied as a higher performance material.

(solvent)
The solvent for redispersing the nanoparticle body is not particularly limited, and various organic solvents can be used regardless of the polarity. For example, pentane, aliphatic saturated hydrocarbons such as hexane and octadecane, aliphatic unsaturated hydrocarbons such as dodecene, tridecene and heptadecene, aromatic hydrocarbons such as toluene, xylene and benzene, and their halides (for example dichloromethane) , Chloroform and carbon tetrachloride), alcohols such as ethanol, methanol and butanol, ketones such as acetone, methyl ethyl ketone and diethyl ketone, esters such as methyl methacrylate, methyl salicylate and ethyl acetate, ethers such as tetrahydrofuran and diethyl ether And amides such as dimethylformamide (DMF), dimethylacetamide (DMAC) and N-methylpyrrolidone (NMP).

(Organic polymer)
The organic polymer that forms the composite material is not particularly limited, and examples thereof include polyolefin resins, acrylate resins, polycarbonate resins, and polyester resins.

(Manufacturing method of nanoparticle body)
It is preferable that the metal or metal oxide nanoparticles include titanium oxide nanoparticles, and a mixing step of mixing the aqueous solution containing the surfactant with the aqueous solution containing the nanoparticles. Since the mixing property of the nanoparticles and the surfactant is improved, it is easy to uniformly coat each particle surface of the nanoparticles. More preferably, in the mixing step, an aqueous solution containing the surfactant is quickly added to the diluted aqueous solution while stirring, and the stirring is further performed. The surface of the particles can be more uniformly coated with the surfactant. Moreover, it is preferable to include the drying process which dries the particle | grains collect | recovered after mixing. Since the nanoparticle body is obtained as a dried powder, it can be easily redispersed in another solvent. Moreover, handling and carrying become easy. Moreover, since the surface of the nanoparticle body is coated, it is well-organized even if it is dried, and the powder is not easily scattered. Therefore, it is excellent also in safety.

  In the mixing step, the amount of the surfactant is preferably 1 mmol or more and 3 mmol or less with respect to 1 g of titanium oxide. Even if it exceeds 3 mmol with respect to 1 g of titanium oxide, the surfactant has high dispersibility but does not contribute to surface modification. Therefore, in terms of cost, it is preferably 3 mmol or less. Further, when the surfactant exceeds 3 mmol, it becomes easy for the surfactants to form a bimolecular layer with the hydrophilic group facing outward. Therefore, it is preferably 3 mmol or less in terms of the recovery rate of the nanoparticle body. Further, it is preferable that the amount of the additive is as small as possible because there are few impurities. On the other hand, if the amount is less than 1 mmol, the particle surface cannot be sufficiently covered, and therefore, it is preferably 1 mmol or more from the viewpoint of dispersibility of the obtained nanoparticle body. Even if 1 mmol is sufficient for 1 g of titanium oxide, the particle surface can be sufficiently coated and has high dispersibility. However, if it is 2 mmol or more for 1 g of titanium oxide, a dispersion obtained by dispersing the resulting nanoparticle in an organic solvent. The transparency of is extremely high regardless of the polarity of the solvent.

  Alternatively, the metal or metal oxide nanoparticles are iron oxide nanoparticles, and the surfactant is mixed in an aqueous solution in which an aqueous iron hydroxide solution is heated to produce iron oxide in the aqueous solution It is preferable to contain. It is easy to uniformly coat the surface of each nanoparticle with a surfactant. Moreover, it is preferable to collect the precipitate produced in the mixed liquid with a magnet and to dry it into a powder. Since it is hard to contain impurities and a nanoparticle body is obtained as a dry powder, it can be easily redispersed in another solvent. Moreover, handling and carrying become easy. Moreover, since the surface of the nanoparticle body is coated, it is well-organized even if it is dried, and the powder is not easily scattered. Therefore, it is excellent also in safety.

  Alternatively, it is preferable that the metal or metal oxide nanoparticles include silver nanoparticles, and a mixing step of mixing an aqueous solution containing the surfactant and the reducing agent in an aqueous silver nitrate solution. Since the coating with the surfactant is simultaneously performed at the stage of generating the silver colloid, it is easy to uniformly coat the surface of each nanoparticle. It is preferable to add toluene to the mixed liquid to extract particles in the organic layer, collect the organic layer, evaporate the solvent to dryness, and form a powder.

  Hereinafter, although the present invention is explained using an example, the present invention is not limited to this at all.

<Preparation of Example 1A of Nanoparticles and Example 1Aa of Nanoparticle Dispersion>
FIG. 1 is a production flow diagram of Example 1A of the nanoparticle body of the present invention and Example 1Aa of the nanoparticle dispersion of the present invention. Nanoparticle dispersion example 1Aa is made from nanoparticle body example 1A. The manufacturing process of Example 1A of the nanoparticle body includes a mixing step of mixing the aqueous solution containing the surfactant with the aqueous solution containing nanoparticles. Nanoparticle Dispersion Example 1 Aa in the production process includes a dispersion step of dispersing the nanoparticle body in a nonpolar organic solvent or a polar organic solvent. In detail, it produced as follows.

(Synthesis example of surfactant)
In Example 1A of the nanoparticle body, a surfactant obtained by synthesis as follows was used.

  A reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer was charged with 587 g (1 mol) of poly (12 mol) oxyethylene allyl ether and 1.2 g of boron trifluoride ethyl ether complex, and maintained at 60 ± 5 ° C. 205 g (1 mol) of α-olefin oxide (mixed of 12 and 14 carbon atoms) was added dropwise over 2 hours and aged at the same temperature for 2 hours.

  Next, 71 g (0.5 g) of phosphoric anhydride was added over 2 to 3 hours while maintaining the temperature at 65 ° C. or lower, and then aged at 60 ± 5 ° C. for 3 hours to obtain 10.8 g (0.6 mol of ion-exchanged water). ) Was added, and the mixture was further aged at 80 ° C. for 5 hours to obtain surfactant P12-10.

Surfactant P12-10 synthesized as described above is a phosphoric acid surfactant represented by the above chemical formula (1), where n = 12 in the chemical formula (1), and R ¹ is A phosphoric acid monoester wherein m = 2 and k = 1, centering on an allyl group in which R ² is an alkyl group having 10 carbon atoms and R ² is an alkyl group having 12 carbon atoms, and m = 1 And it is a mixture which has as a main component the phosphoric acid diester whose k = 2. Surfactant P12-10 is a hydrophilic group containing a linear ethylene oxide group having 12 carbon atoms at the position of the carbon atom bonded to the phosphate group which is a functional group bonded to the particle surface on the ionized side. Branched into a hydrophobic group which is a long-chain alkyl group having 10 or 12 carbon atoms.

(Example 1A of nanoparticle body)
First, a nanoparticle Example 1A was prepared. First, 10 g of nitric acid acidic titanium oxide sol having a pH of 1.4 (STS100, crystallite diameter of 5 nm, average particle diameter of 6 to 8 nm, titanium oxide concentration of 20 wt%, manufactured by Ishihara Sangyo Co., Ltd.) was diluted with 80 g of ion-exchanged water. Since the starting raw material is a dispersion of single nanoparticles, when the obtained nanoparticle body is redispersed, if the dispersion is good, it can be dispersed at the primary particle level, and the uniformity can be increased.

  Next, 20 g of an aqueous solution of surfactant P12-10 was added to the diluted solution while stirring. By mixing the surfactant aqueous solution with the dilute aqueous solution of the sol, the mixing property of the nanoparticles and the surfactant is improved, so that it is easy to uniformly coat the surface of each particle of the nanoparticles. In Example 1A, the surfactant was adjusted to a ratio of 1.0 mmol with respect to 1 g of titanium oxide. Since 2 g of titanium oxide was contained in 10 g of the titanium oxide sol, the surfactant was 4.0 mmol. While stirring, an aqueous solution containing a surfactant was quickly added to the diluted aqueous solution, and further stirred. As a result, the surface of the particles can be more uniformly coated with the surfactant.

  Stirring was performed in a beaker using a stirrer for 3 hours. FIG. 2 is a diagram showing a state in each production stage of Example 1Aa of the nanoparticle dispersion of the present invention and Example 1Aa of the nanoparticle dispersion of the present invention. FIG. 2 (1) shows a state during stirring.

  Immediately after the addition of the surfactant aqueous solution, the solution became cloudy and white aggregates precipitated. FIG. 2 (2) shows a state where particles are aggregated in the solution. The surfactant serves as a surface coating agent that coats the particle surface to modify the surface of the particle. Precipitated particles were surface-modified with a surfactant. The precipitated aggregate was collected by centrifugation and washed 4 times with pure water. By washing, the surfactant and nitric acid which are not bonded to the particles are removed. The recovery was close to 100%.

  Next, vacuum drying was performed at room temperature all day and night (17 hours). As a result, the water was removed, and Example 1A of the nanoparticulate body in a powder state was obtained. FIG. 2 (3) shows the dried state. In FIG. 2 (3), the surface of the rounded particle is coated with a surfactant that protrudes in a needle shape. Nanoparticles were obtained as a dry powder.

(Nanoparticle dispersion example 1Aa)
Ethanol (EtOH: C ₂ H ₅ OH) (99.5% special grade, while performing ultrasonic irradiation for 2 minutes 5 times so that the particle concentration of the powder of Example 1A of the produced nanoparticle body was 3 wt%, Example 1Aa of a nanoparticle dispersion was obtained by dispersing in Kanto Chemical Co., Ltd.). FIG. 2 (4) shows a state in which Example 1A of the nanoparticle dispersion is dispersed in Example 1Aa of the nanoparticle dispersion. By performing ultrasonic irradiation, the dispersion is performed while preventing aggregation, so that a more uniform dispersion can be obtained.

<Production of Example 1A ′ and Example 1A ″ of Nanoparticles>
In Example 1A, the surfactant P12-10 was adjusted to a ratio of 1.0 mmol with respect to 1 g of titanium oxide. As a modification, the ratio of the surfactant P12-10 to 1 g of titanium oxide was changed to 2.0 mmol. This was designated as nanoparticle Example 1A ′. Example 1A ′ was produced in the same manner as Example 1A of the nanoparticle body described above, except for the other points. The recovery was close to 100%. Nanoparticles of Example 1A ″ were prepared by changing the ratio of the surfactant P12-10 to 1 g of titanium oxide to 3.0 mmol. Example 1A ″ was produced in the same manner as Example 1A of the nanoparticle body described above, except for the other points. The recovery rate was about 50%. When the amount of the surfactant becomes too large, it is considered that the surfactant molecules easily form a bimolecular layer with the hydrophilic group facing outward, and the recovery rate is slightly lowered.

<Preparation of Example 1B, Example 1B ′ and Example 1B ″ of Nanoparticles>
As another modification, in place of surfactant P12-10, surfactant P12-14 (α-olefin oxide (mixed of 12 and 14 carbon atoms), 205 g (1 mol) was replaced with α-olefin oxide (16 carbon atoms, 18 mixture) Except for changing to 271 g (1 mol), the synthesis method is the same as the synthesis method of the surfactant P12-10 described above, and R ² in the chemical formula (1) is an alkyl group having 14 carbon atoms. Example 1B of a nanoparticle was obtained by using a mixture that was the same as surfactant P12-10 except that R ² was a mixture centered on an alkyl group having 16 carbon atoms. Further, Example 1B ′ of the nanoparticle body was obtained by changing the ratio of the surfactant P12-14 to 1 g of titanium oxide to 2.0 mmol, and Example 1B ″ of the nanoparticle body was obtained by changing the ratio to 3.0 mmol. . Except for the points described above, the nanoparticle body was prepared in the same manner as in Example 1A.

<Production of Nanoparticle Example 1C, Example 1C ′ and Example 1C ″>
As another modification, instead of surfactant P12-10, surfactant P8-10 (poly (12 mole) oxyethylene allyl ether 587 g (1 mole) was replaced with poly (8 mole) oxyethylene allyl ether 410 g. The synthesis method is the same as the synthesis method of the surfactant P12-10 described above except that it is changed to (1 mol), and is the same as that of the surfactant P12-10 except that n = 8 in the chemical formula (1). The mixture was designated as nanoparticle Example 1C. Nanoparticles of Example 1C ′ were prepared by changing the ratio of surfactant P8-10 to 1 g of titanium oxide to 2.0 mmol, and Examples 1C ″ of Nanoparticles were obtained by changing the ratio to 3.0 mmol. Surfactant P8-10 used in these examples is the same as surfactant P12-10 except for the number of carbon atoms n of ethylene oxide. Except for the points described above, the nanoparticle body was prepared in the same manner as in Example 1A.

<Production of Nanoparticle Example 1D, Example 1D ′ and Example 1D ″>
Similarly, instead of surfactant P12-10, surfactant P16-10 (poly (12 mol) oxyethylene allyl ether 587 g (1 mol) was replaced with poly (16 mol) oxyethylene allyl ether 763 g (1 mol). The synthetic method is the same as the synthetic method of the surfactant P12-10 described above except that it is changed to)), and the mixture is the same as the surfactant P12-10 except that n = 16 in the chemical formula (1). This was designated as nanoparticle Example 1D. Nanoparticles of Example 1D ′ were prepared by changing the ratio of surfactant P16-10 to 1 g of titanium oxide to 2.0 mmol, and Examples 1D ″ of Nanoparticles were obtained by changing the ratio to 3.0 mmol. Surfactant P16-10 used in these examples is the same as surfactant P12-10 except for the number of carbon atoms n of ethylene oxide. Except for the points described above, the nanoparticle body was prepared in the same manner as in Example 1A.

<Preparation of Example 2A of Nanoparticle Body>
As another modification, Example 1A in which the type of particles in Example 1A was changed to iron oxide instead of titanium oxide was used as Example 2A. Example 2A of the nanoparticulate body is different from Example 1A in the amount of surfactant and the production method, and the surfactant is mixed with an aqueous solution in which iron hydroxide is heated to produce iron oxide in the aqueous solution. A mixing step was included, and the details were prepared as follows.

An aqueous solution in which 0.765 g of ferrous sulfate heptahydrate (FeSO ₄ .7H ₂ O) and 1.23 g of ferric chloride hexahydrate (FeCl ₃ .6H ₂ O) are dissolved in 30 ml of ion-exchanged water. Then, while stirring, 3.75 ml of 25 wt% aqueous ammonia (NH ₄ OH aqueous solution) was dropped to neutralize to obtain an aqueous iron hydroxide solution. After raising the temperature of the aqueous solution to 80 ° C., 0.36 g of surfactant P12-10 was added to the aqueous solution, and the mixture was stirred and mixed at 80 ° C. for 1 hour in a flask with a second oxide. Iron (Fe ₃ O ₄ ) particles were generated and the particle surface was coated with a surfactant. After stirring, the generated particles were collected with a magnet and vacuum-dried at room temperature all day and night (17 hours). Thus, moisture was removed, and Example 2A of a powdered iron oxide nanoparticle body was obtained.

<Preparation of Example 3A of Nanoparticle Body>
As yet another modification, Example 3A in which the type of particles in Example 1A was changed to silver instead of titanium oxide was used as Example 3A. Example 3A of the nanoparticle body differs from Example 1A in the amount of surfactant and the production method, and includes a mixing step of mixing an aqueous solution containing a surfactant and a reducing agent in an aqueous silver nitrate solution, In detail, it produced as follows.

An aqueous solution obtained by dissolving 18 mg of sodium borohydride (NaBH ₄ ) as a reducing agent and 13 mg of surfactant P12-10 in 25 ml of ion-exchanged water is used as one solution, and 21 mg of silver nitrate (AgNO ₃ ) is added in 25 ml. An aqueous solution dissolved in ultrapure water was used as two solutions, and two solutions were added dropwise to the first solution while stirring in an ice bath to prepare an Ag colloid. Further, 50 ml of toluene was added to the Ag colloid thus prepared, and then about 10 ml of 0.1 mol / l phosphoric acid (H ₃ PO ₄ ) aqueous solution was added while stirring, so that the surface of the surfactant P12-10 was increased. The modified silver nanoparticles were extracted into the organic layer. Thereafter, the organic layer was recovered, and the solvent was evaporated to dryness using a rotary evaporator to obtain Example 3A of a silver nanoparticle body in a powder state.

<Preparation of Nanoparticle Dispersion Example 1Aa-10%>
Further, as a modified example of the nanoparticle dispersion example 1Aa, nanoparticle dispersion example 1Aa-10% in which the particle concentration was 10 wt% was produced. Other conditions were the same as in Example 1Aa of the nanoparticle dispersion. The nanoparticle Example 1A was dispersed in an organic solvent even when the particle concentration was as high as 10 wt%.

<Preparation of Example 1Ab, Example 1Ac, and Example 1Ad of Nanoparticle Dispersion>
As a modification of Example 1Aa of the nanoparticle dispersion, instead of dispersing Example 1A of the nanoparticle body in ethanol, tetrahydrofuran (THF: C ₄ H ₈ O) (for stabilizer-containing dehydrated organic synthesis, The product dispersed in Wako Pure Chemical Industries, Ltd. was used as Example 1Ab of the nanoparticle dispersion, and methyl methacrylate (MMA: CH ₂ ═C (CH ₃ ) COOCH ₃ ) (monomer, Wako Special Grade, Wako Pure Chemicals) The product dispersed in Kogyo Kogyo Co., Ltd. was used as Example 1Ac of the nanoparticle dispersion, and dispersed in toluene (Toluene: CH ₃ (C ₆ H ₅ )) (99.5%, manufactured by Wako Pure Chemical Industries, Ltd.) This was designated as Example 1Ad of the nanoparticle dispersion. Example 1Ac, Example 1Ac, and Example 1Ac were each produced in the same manner as Example 1Aa of the nanoparticle dispersion described above. Example 1A was easily dispersed in any organic solvent such as ethanol, THF, MMA, and toluene.

<Production of Nanoparticle Dispersion 1A′a, Example 1A′b, Example 1A′c, and Example 1A′d>
As another modified example, Example 1A ′ of the nanoparticle dispersion was obtained by dispersing Example 1A ′ of the nanoparticle body in ethanol into Example 1A′a of the nanoparticle dispersion and Example 1A of the nanoparticle dispersion was dispersed in tetrahydrofuran. The sample dispersed in methyl methacrylate was designated as Example 1A′c of the nanoparticle dispersion, and the product dispersed in toluene was designated as Example 1A′d of the nanoparticle dispersion. These examples were prepared in the same manner as Example 1Aa of the nanoparticle dispersion described above in other respects. Example 1A ′ was easily dispersed in any organic solvent such as ethanol, THF, MMA, and toluene.

<Preparation of other examples of nanoparticle dispersion>
In addition, Example 1A ″, Example 1B, Example 1B ′, Example 1B ″, Example 1C, Example 1C ′, Example 1C ″, Example 1D, Example 1D ′ of nanoparticle bodies Similarly, for Example 1D ″, Example 2A, and Example 3A, those dispersed in ethanol were used as Example 1A ″ a, Example 1Ba, and Example 1B′a, respectively. Example 1B ″ a, Example 1Ca, Example 1C′a, Example 1C′a, Example 1Da, Example 1D′a, Example 1D ″ a, Example 2Aa, Example 2Aa, Tetrahydrofuran Example 1A ″ b, Example 1Bb, Example 1B′b, Example 1B ″ b, Example 1Cb, Example 1C′b, and Example 1C ′ of nanoparticle dispersions respectively dispersed in 'B, Example 1Db, Example 1D'b, Example 1D'b, Example 2Ab, Example Ab and dispersed in methyl methacrylate were Example 1A ″ c, Example 1Bc, Example 1B′c, Example 1B ″ c, Example 1Cc, and Example 1C ′ of nanoparticle dispersions, respectively. c, Example 1C ″ c, Example 1Dc, Example 1D′c, Example 1D ″ c, Example 2Ac, and Example 3Ac, and examples of nanoparticle dispersions dispersed in toluene, respectively 1A ″ d, Example 1Bd, Example 1B′d, Example 1B ″ d, Example 1Cd, Example 1C′d, Example 1C ″ d, Example 1Dd, Example 1D′d, Example Example 1D ″ d, Example 2Ad, and Example 3Ad were used. These examples of nanoparticle dispersions were otherwise produced in the same manner as the nanoparticle dispersion Example 1Aa described above. Example 1A ″, Example 1B, Example 1B ′, Example 1B ″, Example 1C, Example 1C ′, Example 1C ″, Example 1D, Example 1D ′, Example of nanoparticle body Example 1D ″, Example 2A, and Example 3A were all easily dispersed in any organic solvent such as ethanol, THF, MMA, and toluene.

<Production of comparative example of nanoparticle body and comparative example of nanoparticle dispersion>
A nitric acid acidic titanium oxide sol (STS100, crystallite diameter 5 nm, average particle diameter 6-8 nm, titanium oxide concentration 20 wt%, manufactured by Ishihara Sangyo Co., Ltd.) was dried with hot air at 100 ° C. to obtain Comparative Example 1X of nanoparticle body It was. As another comparative example, a dispersion obtained by diluting 10 g of nitric acid acidic titanium oxide sol (STS100, crystallite diameter 5 nm, average particle diameter 6 to 8 nm, titanium oxide concentration 20 wt%, manufactured by Ishihara Sangyo Co., Ltd.) with ion exchange water 80 g The surfactant was not added to the liquid, acetone was added to precipitate the particles, and the same centrifugal separation as in Example 1A was performed, followed by hot air drying at 100 ° C., and Comparative Example 1Y of the nanoparticle body was obtained. Obtained. Comparative Example 1Y was produced in the same manner as Example 1A of the nanoparticle body described above, except for the above points.

  Further, as a comparative example in which the surfactant is different, instead of the surfactant P12-10 as the surfactant in Example 1A, the following chemical formula (2)

  The anion polymerizable surfactant (SE-10N, manufactured by ADEKA Corporation) (hereinafter referred to as “surfactant S10”) represented by the formula (1) is a nanoparticle having a ratio of 1.0 mmol to 1 g of titanium oxide. Comparative Example 2S for Particles, Comparative Example 2S ′ for Nanoparticles with a Ratio of Surfactant S10 to 1 g of Titanium Oxide of 2.0 mmol, and Comparative Example 2S for Nanoparticles with 3.0 mmol ″. Comparative Example 2S, Comparative Example 2S ′, and Comparative Example 2S ″ were produced in the same manner as in Example 1A of the nanoparticle body described above. Surfactant S10 has a hydrophobic group branched from an ethylene oxide group, which is a hydrophilic group, in a functional group bonded to the particle surface.

  Further, as another comparative example in which the surfactant is different, instead of the surfactant P12-10 as the surfactant in Example 1A, the following chemical formula (3)

  (However, R is an alkyl group having 12 to 14 carbon atoms) Anionic polymerizable surfactant (Eleminol JS-20 active ingredient 38.7%, manufactured by Sanyo Chemical Industries, Ltd.) (hereinafter referred to as surfactant) S0) and a ratio of 1.0 mmol with respect to 1 g of titanium oxide, a comparative example 3T of nanoparticle body, and a ratio of surfactant S0 with respect to 1 g of titanium oxide set to 2.0 mmol. The nanoparticle body Comparative Example 3T ′ was prepared, and the nanoparticle body Comparative Example 3T ″ was prepared as 3.0 mmol. Comparative Example 3T, Comparative Example 3T ′, and Comparative Example 3T ″ were prepared in the same manner as in Example 1A of the nanoparticle body described above. The surfactant S0 has a hydrophobic group branched at a carbon atom bonded to a functional group bonded to the particle surface.

  Similarly, Comparative Example 2S, Comparative Example 2S ′, Comparative Example 2S ″, Comparative Example 3T, Comparative Example 3T ′, and Comparative Example 3T ″, which are nanoparticle bodies, are dispersed in ethanol in the same manner. Comparative Example 2Sa, Comparative Example 2S′a, Comparative Example 2S′a, Comparative Example 3Ta, Comparative Example 3T′a, Comparative Example 3T ″ a, and Nanoparticle Dispersions Example 2Sb, Comparative Example 2S′b, Comparative Example 2S ″ b, Comparative Example 3Tb, Comparative Example 3T′b, and Comparative Example 3T ″ b, which were dispersed in methyl methacrylate and compared with a nanoparticle dispersion 2Sc, Comparative Example 2S′c, Comparative Example 2S ″ c, Comparative Example 3Tc, Comparative Example 3T′c, Comparative Example 3T ″ c, and what was dispersed in toluene, Comparative Example 2Sd of Nanoparticle Dispersion, Comparative Example 2S′d, Comparative Example 2S ″ d, Comparative Example 3Td, Comparative Example 3T′d It was a comparative example 3T''d. These comparative examples were produced in the same manner as Example 1Aa of the nanoparticle dispersion described above, except for the above points.

  Detailed information on the surfactant P12-10 used in Example 1A and the like of the present invention, the surfactant S10 used in Comparative Example 2S and the surfactant S0 used in Comparative Example 3T and the like is shown in Table 1 below. Indicates.

For P12-10 and S0, the alkyl groups R ² and R of the surfactant are a mixture of a plurality of carbon atoms, and S0 is mostly those having 12 carbon atoms. , S0 is calculated as R = C ₁₂ H ₂₅ in the chemical formula (3), and P12-10 is m = 2, k = 1, n = 12, R ¹ = CH ₂ CHCH ₂ in the chemical formula (1), Calculated as R ² = C ₁₀ H ₂₁ .

<Characteristics of nanoparticle bodies: qualitative analysis>
The structure of the particle surface was qualitatively analyzed by spectrum measurement with FT-IR (Fourier Transform Infrared Spectroscopy) for each of Examples and Comparative Examples and surfactants. For each example, the sample was adjusted at a mixing ratio of 0.03 g of sample to 0.4 g of potassium bromide (KBr) and each comparative example at a mixing ratio of 0.5 g of sample to 0.05 g of KBr. Further, for P12-10 as a surfactant, KBr 0.3987 g for 0.0034 g sample, KBr 0.3700 g for 0.0027 g sample for P12-14, KBr 0.4078 g for 0.0051 g sample for P8-10, P16- 10 was adjusted with a mixing ratio of KBr 0.3979 g to 0.0042 g of the sample.

FIG. 3 is a diagram showing FT-IR spectra of Example 1A, Example 1A ′, Example 1A ″, Comparative Example 1X, and surfactant P12-10 of the nanoparticle body of the present invention. In FIG. 3, a is Example 1A ″, b is Example 1A ′, c is Example 1A, d is Comparative Example 1X, and e is the spectrum of surfactant P12-10. In the spectra of Example 1A ″, Example 1A ′, and Example 1A, a C—H stretching vibration peak in the vicinity of 2800 to 3000 cm ⁻¹ considered to be derived from the surfactant was observed. Moreover, the peak of P = O stretching vibration of the hydrophilic group of the surfactant was observed. From these results, it was confirmed that Example 1A, Example 1A ′, and Example 1A ″ were coated with the surfactant P12-10.

FIG. 4 is a diagram showing FT-IR spectra of Example 1B, Example 1B ′, Example 1B ″, Comparative Example 1X, and surfactant P12-14 of the nanoparticle body of the present invention. In FIG. 4, a shows the spectrum of Example 1B ″, b shows Example 1B ′, c shows Example 1B, d shows Comparative Example 1X, and e shows the spectrum of surfactant P12-14. In the spectra of Example 1B ″, Example 1B ′, and Example 1B, a C—H stretching vibration peak in the vicinity of 2800 to 3000 cm ⁻¹ considered to be derived from the surfactant was observed. Moreover, the peak of P = O stretching vibration of the hydrophilic group of the surfactant was observed. From these results, it was confirmed that Example 1B and Example 1B ′ were coated with the surfactant P12-14.

FIG. 5 is a diagram showing FT-IR spectra of Example 1C, Example 1C ′, Example 1C ″, Comparative Example 1X and surfactant P8-10 of the nanoparticle body of the present invention. In FIG. 5, a shows the spectrum of Example 1C ″, b shows Example 1C ′, c shows Example 1C, d shows Comparative Example 1X, and e shows the spectrum of surfactant P8-10. In the spectra of Example 1C ″, Example 1C ′, and Example 1C, a C—H stretching vibration peak in the vicinity of 2800 to 3000 cm ⁻¹ considered to be derived from the surfactant was observed. Moreover, the peak of P = O stretching vibration of the hydrophilic group of the surfactant was observed. From these results, it was confirmed that Example 1C and Example 1C ′ were coated with the surfactant P8-10.

FIG. 6 is a diagram showing FT-IR spectra of Example 1D, Example 1D ′, Example 1D ″, Comparative Example 1X, and surfactant P16-10 of the nanoparticle body of the present invention. In FIG. 6, a is Example 1D ″, b is Example 1D ′, c is Example 1D, d is Comparative Example 1X, and e is the spectrum of the surfactant P16-10. In the spectra of Example 1D ″, Example 1D ′, and Example 1D, a C—H stretching vibration peak in the vicinity of 2800 to 3000 cm ⁻¹ considered to be derived from the surfactant was observed. Moreover, the peak of P = O stretching vibration of the hydrophilic group of the surfactant was observed. From these results, it was confirmed that Example 1D and Example 1D ′ were coated with the surfactant P16-10.

  Therefore, these examples show the same peak as the surfactant having a hydrophilic group having an affinity for a polar organic solvent and a hydrophobic group having an affinity for a nonpolar organic solvent. It can be said that the nanoparticle body has a hydrophilic group having an affinity for an organic solvent and a hydrophobic group having an affinity for a nonpolar organic solvent on the particle surface. From the type of surfactant, the hydrophilic group includes a long-chain ethylene oxide group, specifically a polyoxyethylene group having an n number of 8 to 16, and the hydrophobic group is a long-chain alkyl group. A long-chain alkyl group having 10 to 16 carbon atoms. The hydrophilic group and the hydrophobic group are branched in one molecule, and the branch point is a carbon atom ester-bonded to a phosphate group bonded to the surface of the nanoparticle.

FIG. 7 is a diagram showing FT-IR spectra of Comparative Example 2S, Comparative Example 2S ′, Comparative Example 2S ″, Comparative Example 1X, and Surfactant S10 of the nanoparticle body of the present invention. In FIG. 7, a is the comparative example 2S ″, b is the comparative example 2S ′, c is the comparative example 2S, d is the comparative example 1X, and e is the spectrum of the surfactant S10. In the spectra of Comparative Example 2S ″, Comparative Example 2S ′, and Comparative Example 2S, C—H stretching vibration peaks in the vicinity of 2800 to 3000 cm ⁻¹ considered to be derived from the surfactant, and 1461, 1512, and 1609 cm ⁻¹ phenyl rings A peak of stretching vibration was observed. Moreover, the peak of O = S = O symmetrical stretching vibration of the hydrophilic group of the surfactant was observed. From these results, it was confirmed that Comparative Example 2S, Comparative Example 2S ′, and Comparative Example 2S ″ were coated with the surfactant S10.

FIG. 8 is a diagram showing FT-IR spectra of Comparative Example 3T, Comparative Example 3T ′, Comparative Example 3T ″, Comparative Example 1X, and Surfactant S0 of the nanoparticle body of the present invention. In FIG. 8, a is a comparative example 3T ″, b is a comparative example 3T ′, c is a comparative example 3T, d is a comparative example 1X, and e is a spectrum of the surfactant S0. Comparative Example 3T'', Comparative Example 3T', in the spectrum of Comparative Example 3T, a C-H stretching vibration peak near 2800 to 3000 cm ^-1, which is believed to be derived from the surfactant, the C = O stretching vibration of 1740 cm ^-1 A peak was observed. Moreover, the peak of O = S = O symmetrical stretching vibration of the hydrophilic group of the surfactant was observed. From these results, it was confirmed that Comparative Example 3T, Comparative Example 3T ′, and Comparative Example 3T ″ were coated with the surfactant S0.

<Characteristics of nanoparticle bodies: quantitative analysis>
Quantitative analysis of surfactants can also be done by thermogravimetric analysis (TGA). For example, when the hydrophilic group is a sulfonic acid surfactant, non-volatile components such as titanium sulfate may remain and burnt incompletely. Because there is a problem that accurate quantification is difficult, there was a quantitative analysis by organic elemental analysis. Table 2 below shows Example 1A, Example 1A ′, Comparative Example 2S, Comparative Example 2S ′, Comparative Example 2S ″, Comparative Example 3T, Comparative Example 3T ′, and Comparative Example 3T ″ of the nanoparticle body of the present invention. The quantitative analysis result by organic elemental analysis of is shown.

  The bond amount in the table is the value of D calculated by the following mathematical formulas (1) to (3).

  A in the above formula (1) is the carbon content of Table 2, which is the carbon content (wt%) of the examples and comparative examples. For example, the carbon content of Comparative Example 2S is 21.35 (wt%), and the carbon content of Comparative Example 2S ′ is 21.14 (wt%). Further, B in the mathematical formula (1) is the molecular weight (g / mol) of the dissociated surfactant. As the value of B, the value of the molecular weight (when the hydrophilic group is dissociated) shown in Table 1 above was used. C in the formula (1) is the carbon number (#) of each phosphate surfactant. As the value of C, the value of the number of carbon atoms per molecule in Table 1 above was used. S in the above mathematical formula (1) is the amount of surfactant (wt%) of the particles modified by coating with the surfactant.

  T in the above mathematical formula (2) is the amount of titanium oxide (wt%) of the particles modified by coating with a surfactant.

  D in the mathematical formula (3) is a binding amount, which is the binding amount (mmol / g) of the surfactant on the surface of the particle that has been modified by coating with a surfactant per 1 g of titanium oxide.

  From Table 2, in Comparative Example 2S, Comparative Example 2S ′, and Comparative Example 2S ″, the binding amount of surfactant S10 per gram of titanium oxide was about 0.68 mmol, and there was almost no difference depending on the addition amount. The binding amount of the surfactant S0 reached the saturation binding amount in Comparative Example 3T ′ in which the addition amount was 2 mmol. In surfactant P12-10, a maximum of 1.13 mmol was bound. Whether due to the difference in the dissociation state of the sulfonic acid in the aqueous solution, the surfactant S0 is more reactive than the surfactant S10, and Comparative Example 3T, Comparative Example 3T ′, and Comparative Example 3T ″ are more The amount of binding was larger than those of Comparative Example 2S, Comparative Example 2S ′, and Comparative Example 2S ″. In Comparative Example 2S, Comparative Example 2S ′, and Comparative Example 2S ″, one Ti—OH molecule on the particle surface is bonded to one molecule of sulfonic acid. In these Comparative Examples, a considerable amount of unbonded hydroxyl groups on the particle surface. Is considered to remain.

<Characteristics of nanoparticle dispersion: average agglomerated particle size>
For each nanoparticle dispersion, the strength-based average aggregated particle size (50% size) in each solvent was measured immediately after dispersion by dynamic light scattering (DLS). FIG. 9 is a diagram showing the measurement results obtained by the dynamic light scattering method of Examples 1Aa to d, Examples 1A′a to d, and Examples 1A′a to d of the nanoparticle dispersion of the present invention. In FIG. 9, (a) is a nanoparticle dispersion in which Example 1A of the nanoparticle body is dispersed, and Example 1Aa of the nanoparticle dispersion in which the solvent is ethanol, and Implementation of the nanoparticle dispersion in which THF is used. Example 1Ab, Example 1Ac of Nanoparticle Dispersion that is MMA, Example 1Ad of Nanoparticle Dispersion that is Toluene (These Examples are collectively referred to as Examples 1Aa to d. The following is also collectively expressed) (B) shows the average agglomerated particle size measured for Examples 1A′a to d of the nanoparticle dispersion and (c) shows Examples 1A′a to d of the nanoparticle dispersion. Example 1Aa and Example 1A′a have substantially the same average aggregate particle diameter, and Example 1A′b and Example 1A ″ b have approximately the same average aggregate particle diameter. The plots overlap.

  FIG. 10 is a diagram showing the measurement results obtained by the dynamic light scattering method of Examples 1Ba to d, Examples 1B′a to d, and Examples 1B ″ a to d of the nanoparticle dispersion of the present invention. 10A is a nanoparticle dispersion example 1Ba-d, FIG. 10B is a nanoparticle dispersion example 1B′a-d, and FIG. 10C is a nanoparticle dispersion example 1B ″. The average aggregate particle diameter measured about ad is shown. Example 1B′c and Example 1B ″ c have substantially the same average aggregate particle diameter, and Example 1B′d and Example 1B ″ d have the same average aggregate particle diameter. , The plots overlap each other.

  FIG. 11 is a diagram showing the measurement results obtained by the dynamic light scattering method of Examples 1Ca to d, Examples 1C′a to d, and Examples 1C′a to d of the nanoparticle dispersion of the present invention. 11A is a nanoparticle dispersion example 1Ca to d, FIG. 11B is a nanoparticle dispersion example 1C′a to d, and FIG. 11C is a nanoparticle dispersion example 1C ″. The average aggregate particle diameter measured about ad is shown. Example 1C′b and Example 1C ″ b have the same average aggregate particle diameter, and Example 1C′c and Example 1C ″ c have the same average aggregate particle diameter. , The plots overlap each other.

  FIG. 12 is a diagram showing the measurement results obtained by the dynamic light scattering method of Examples 1Da to d, Example 1D′a to d, and Example 1D ″ a to d of the nanoparticle dispersion of the present invention. 12A is a nanoparticle dispersion example 1Da-d, FIG. 12B is a nanoparticle dispersion example 1D′a-d, and FIG. 12C is a nanoparticle dispersion example 1D ″. The average aggregate particle diameter measured about ad is shown. Example 1D′b and Example 1D ″ b have substantially the same average aggregate particle diameter, and Example 1D′c and Example 1D ″ c have the same average aggregate particle diameter. , The plots overlap each other.

  As shown in FIGS. 9-12, nanoparticle dispersion examples 1Aa-d, 1A′a-d, 1A′′a-d, 1Ba-d, 1B′a. -D, Example 1B "a-d, Example 1Ca-d, Example 1C'a-d, Example 1C" a-d, Example 1Da-d, Example 1D'a-d, Implementation In all of Examples 1D ″ a to d, the average aggregated particle diameter by the dynamic light scattering method was 200 nm or less, and the particles were dispersed. Therefore, in these examples of nanoparticle dispersions, the dispersibility of the particles is good and the uniformity is excellent. In addition, Example 1A, Example 1A ′, Example 1A ″, Example 1B, Example 1B ′, Example 1B ″, Example 1C, Example 1C ′, and Example 1C ″ of nanoparticulate bodies. In addition, it can be said that all of Examples 1D, 1D ′, and 1D ″ have high dispersibility in any solvent of ethanol, THF, MMA, and toluene.

  In any of the nanoparticle examples shown in FIGS. 9 to 12, the particle surface is coated with a phosphate surfactant having both ethylene oxide and a long-chain alkyl group. Therefore, these examples have both hydrophilic groups and hydrophobic groups on the particle surface, and when redispersed in a solvent, as shown in FIGS. 9 to 12, in a wide range of solvents from a high polarity solvent to a low solvent. And has excellent dispersibility. In these examples, surfactants P12-10, P12-14, P8-10, and P16-10 used for coating the particle surface are both ethylene oxide having hydrophilicity and long-chain alkyl group having hydrophobicity. And having both a hydrophilic group and a hydrophobic group improved the dispersibility of the nanoparticle body. Since these surfactants are close to the branching of the alkyl group and the ethylene oxide group from the phosphate group bonded to the particle surface, they can be dispersed extremely well in both polar and nonpolar solvents.

  In these examples, the surfactant used for coating the particle surface is any of P12-10, P12-14, P8-10, and P16-10, as shown in FIGS. The amount was 1.0 mmol to 3.0 mmol with respect to 1 g of titanium oxide, and high dispersibility was shown. In these examples, except when the surfactant is P16-10, it is 3.0 mmol with respect to 1 g of titanium oxide, the average aggregate particle size is 50 nm or less, and is redispersed in the solvent to near the primary particle size. It showed extremely high dispersibility. Therefore, the ethylene oxide group is more preferable in terms of dispersibility when n = 8 to 12 in the above chemical formula (1).

  In these examples, when the surfactant used for coating the particle surface is P12-14 or P8-10, as shown in FIGS. 10 and 11, the amount of the surfactant is 1 g of titanium oxide. On the other hand, the dispersibility was better at 2 mmol or more than 1.0 mmol. Therefore, it is more preferable in terms of dispersibility to increase the amount of the surfactant to 2 mmol or more.

  On the other hand, as shown in FIG. 9, an example is a nanoparticle body coated with a surfactant P12-10 in which n = 8 to 12 in the above chemical formula (1) for the ethylene oxide group of the surfactant In each of 1A, Example 1A ′ and Example 1A ″, extremely high dispersibility was exhibited regardless of the polarity of the solvent.

  As shown in FIG. 9, in the coating using the surfactant P12-10, even in Example 1A where the amount of the surfactant is 1.0 mmol with respect to 1 g of titanium oxide, the particle surface is sufficiently coated, High dispersibility was exhibited regardless of the polarity of the solvent. Dispersibility was further improved by setting the ratio to 2.0 mmol or more with respect to 1 g of titanium oxide.

  In terms of cost, it is preferable that the amount of the surfactant is small. Moreover, since impurities increase as the amount of additives increases, it is preferable to reduce the amount of the surfactant from the viewpoint of purity. Further, if the amount is too large, the amount of the surfactant that does not contribute to the surface modification increases and it becomes easy to form a bimolecular layer. Therefore, it is preferable that the amount of the surfactant is an appropriate amount from the viewpoint of the recovery rate. However, it is not preferable if the amount of the surfactant is too small to coat the particles and the dispersibility of the particles obtained is poor. In the surface coating using the surfactant P12-10, even Example 1A added in a small amount of 1 mmol with respect to 1 g of titanium oxide shows high dispersibility, so that it is extremely effective in terms of cost, purity, and recovery.

  When the surfactant was P12-10, Example 1A, which was added in a small amount in any solvent, showed extremely high dispersibility with an average aggregated particle size of 50 nm or less. Therefore, in the example of the nanoparticle body in which the surfactant is P12-10, there is little aggregation of the nanoparticles in the dispersion regardless of the polarity of the solvent, and the uniformity is excellent. In particular, in Examples 1A′a to d and Examples 1A′a to d of the nanoparticle dispersion, the average aggregated particle size by the dynamic light scattering method was 30 nm or less, which was about the primary particle size. Therefore, in the example of the nanoparticle body in which the surfactant is P12-10 and the amount of the surfactant is 2 mmol or more with respect to 1 g of titanium oxide, the nanoparticle in the dispersion regardless of the polarity of the solvent. There is very little aggregation and excellent uniformity.

  FIG. 13: is a figure which shows the measurement result by the dynamic light-scattering method immediately after dispersion | distribution about Example 1D''a-d of the nanoparticle dispersion of this invention, and several days after. Example 1D ″ was also dispersed in the solvent and allowed to stand for several days, so that it was redispersed well in all the solvents to near the primary particle size. Therefore, even in the example of the nanoparticle body in which the surfactant used for coating the particle surface is P16-10, the aggregation of the nanoparticles is small and excellent in uniformity in the dispersion regardless of the polarity of the solvent. .

  Example 2A and Example 3A of nanoparticle bodies are also easily dispersed in any solvent of ethanol, THF, MMA, and toluene, and Examples 2Aa to d and Examples 3Aa to d of nanoparticle dispersions are dispersed. Obtained.

  FIG. 14 is a diagram showing measurement results of Comparative Example 2Sa to d, Comparative Example 2S′a to d, and Comparative Example 2S ″ a to d of the nanoparticle dispersion of the present invention by a dynamic light scattering method. In FIG. 14, (a) is a nanoparticle dispersion comparative example 2Sa-d, (b) is a nanoparticle dispersion comparative example 2S′a-d, and (c) is a nanoparticle dispersion comparative example 2S ″. The average aggregate particle diameter measured about ad is shown. Nanoparticles Comparative Example 2S, Comparative Example 2S ′ and Comparative Example 2S ″ all showed high dispersibility when the solvent was ethanol. However, when the polarity was reduced, the dispersibility deteriorated. The aggregated particle diameter was 50 nm or more, MMA had an average aggregate particle diameter of about 100 nm, and toluene had an average aggregate particle diameter of 100 nm or more. There was no difference in dispersibility depending on the amount of surfactant S10 added. In Comparative Example 2S, Comparative Example 2S ′ and Comparative Example 2S ″ of the nanoparticle body, many unbonded residual hydroxyl groups remain, but as the polarity of the solvent decreases, the attractive force between the hydroxyl groups increases. It is thought that dispersibility became low with a solvent having a small polarity.

  Therefore, in the nanoparticle body which coat | covered surfactant S10 on the particle | grain surface, a dispersibility is bad with a nonpolar solvent, and there exists a difference in dispersibility by the polarity of a solvent, and shows high dispersibility irrespective of the polarity of a solvent. I couldn't.

  FIG. 15 is a diagram showing the measurement results by the dynamic light scattering method of Comparative Examples 3Ta to d, Comparative Examples 3T′a to d, and Comparative Examples 3T ″ a to d of the nanoparticle dispersion of the present invention. 15A is a nanoparticle dispersion comparative example 3Ta to d, FIG. 15B is a nanoparticle dispersion comparative example 3T′a to d, and FIG. 15C is a nanoparticle dispersion comparative example 3T ″. The average aggregate particle diameter measured about ad is shown. In all of Comparative Examples 3T, 3T ′ and 3T ″ of the nanoparticle bodies, the solvent is THF and the dispersibility is good. However, when the solvent is ethanol, the average aggregated particle diameter by the dynamic light scattering method is about Dispersibility was very poor at around 1000 nm or more. When the solvent was MMA or toluene, the dispersibility was slightly poor. In particular, when the addition amount of the surfactant was 1.0 mmol with respect to 1 g of titanium oxide, the average aggregated particle size was 200 nm or more, and the dispersibility was extremely poor. When the solvent was THF, MMA, or toluene, the dispersibility improved as the amount of surfactant S0 added increased. On the other hand, when the solvent was ethanol, the aggregation was increased and the dispersibility was deteriorated as the addition amount of the surfactant S0 was increased.

  In Comparative Example 3T, Comparative Example 3T ′ and Comparative Example 3T ″ of nanoparticle bodies, THF showed high dispersibility, but since surfactant S0 has a highly polar ester group, it has low polarity such as MMA and toluene. Aggregation occurs slightly in this solvent, and since the surfactant S0 does not have hydrophilic ethylene oxide, the particle surface of the nanoparticle is hydrophobized, and the dispersibility is poor in ethanol, which is a polar solvent. .

  Therefore, in the nanoparticle body in which the surfactant S0 is coated on the particle surface, the dispersibility is poor with a polar organic solvent, the dispersibility varies depending on the polarity of the solvent, and the dispersibility is high regardless of the polarity of the solvent. I couldn't.

<Characteristics of nanoparticle dispersion: transparency>
Each nanoparticle dispersion was observed for transparency after being allowed to stand for 24 hours after dispersion. Specifically, immediately after each dispersion is placed in a transparent container (18 mm diameter sample bottle), placed in front of a board with black horizontal letters on a white background and allowed to stand for 24 hours. The film was observed and photographed to see if the horizontal text pattern on the screen was transparent and if it settled down.

  FIG. 16 is a diagram showing the results of transparency observation of Examples 1Aa to d and Examples 1A′a to d of the nanoparticle dispersion of the present invention.

In Examples 1Aa to d and Example 1A′a to d of the nanoparticle dispersion, there was no sedimentation and transparency was high. Moreover, there was almost no coloring and therefore the colorlessness was high. In particular, Examples 1Aa to c and Examples 1A'a to d of the nanoparticle dispersion showed very high transparency so that the characters on the board behind the container were clearly visible. In Example 1A and Example 1A ′ of nanoparticle bodies, a nanoparticle dispersion that is a highly transparent and highly colorless TiO ₂ nanoparticle / organic solvent suspension regardless of the polarity of the organic solvent to be redispersed. Can be obtained. In terms of transparency, Example 1A ′ is more preferable in that there is no difference due to the polarity of the solvent.

  FIG. 17 shows the transparency of Example 1A ″ a-d, Example 1B ″ a-d, Example 1C ″ a-d, and Example 1D ″ a-d of the nanoparticle dispersion of the present invention. It is a figure which shows an observation result.

Examples 1A "a-d, Example 1B" a-d, Example 1C "a-d, and Example 1D" a-d of the nanoparticle dispersion are all free from sedimentation and It was so transparent that the characters on the board behind it were clearly visible. Moreover, there was almost no coloring and therefore the colorlessness was high. In particular, in Examples 1A ″ a to d, Example 1B ″ a to d, Example 1C ″ a to d, and Example 1D ″ d of the nanoparticle dispersion, the transparency was particularly high. . Example 1A ″ of the nanoparticle body has TiO ₂ nanoparticles / organic solvent suspension with extremely high transparency and high colorlessness, similar to Example 1A ′, regardless of the polarity of the solvent to be redispersed. can get. Accordingly, in terms of transparency, Example 1A ′ and Example 1A ″ are equally preferred in that there is no difference due to the polarity of the solvent.

Example 1B ″, Example 1C ″, and Example 1D ″ of nanoparticle bodies also have high transparency and high colorlessness of TiO ₂ nanoparticles / organic solvent regardless of the polarity of the solvent to be redispersed. Suspension can be obtained. In particular, in Example 1B ″ and Example 1C ″ of nanoparticulate bodies, oxidation with extremely high transparency and high colorlessness is the same as in Example 1A ″ regardless of the polarity of the solvent to be redispersed. A nanoparticle dispersion that is titanium nanoparticle / organic solvent suspension can be obtained.

  The titanium oxide nanoparticle coated with the surfactant represented by the chemical formula (1) can obtain a highly transparent nanoparticle dispersion regardless of the polarity of the solvent to be redispersed.

  FIG. 18 is a diagram showing the results of transparency observation of Examples 2Aa to d of the nanoparticle dispersion of the present invention. In any organic solvent such as ethanol, THF, MMA, and toluene, the color was brown, but there was no precipitation and the transparency was high. Although it was colored, it was so transparent that the horizontal text pattern on the back was transparent. A highly transparent nanoparticle dispersion has extremely high dispersibility of the nanoparticle body. Therefore, the iron oxide nanoparticle coated with the surfactant represented by the chemical formula (1) can obtain a highly transparent nanoparticle dispersion regardless of the polarity of the solvent to be redispersed.

  FIG. 19 is a diagram showing the results of transparency observation of Examples 3Aa to d of the nanoparticle dispersion of the present invention. In any organic solvent such as ethanol, THF, MMA, and toluene, it was colored yellow, but it had no sedimentation and was highly transparent. Although it was colored, it was so transparent that the horizontal text pattern on the back was transparent. The silver nanoparticle coated with the surfactant represented by the chemical formula (1) can obtain a highly transparent nanoparticle dispersion regardless of the polarity of the solvent to be redispersed.

  FIG. 20 is a diagram illustrating the results of transparency observation of Comparative Examples 2Sa to d, Comparative Examples 2S′a to d, and Comparative Examples 2S ″ a to d of the nanoparticle dispersion of the present invention. Comparative Examples 2Sa to d, Comparative Examples 2S′a to d, and Comparative Examples 2S ″ a to d were all free from sedimentation, and the transparency was high when the solvent was ethanol, but transparent in the order of THF, MMA, and toluene. The nature became low and became cloudy. When the dispersibility was poor, the transparency of the nanoparticle dispersion was also low. There was no difference in dispersibility depending on the amount of surfactant S10 added.

  FIG. 21 is a diagram showing the results of transparency observation of Comparative Examples 3Ta to d, Comparative Examples 3T′a to d, and Comparative Examples 3T ″ a to d of the nanoparticle dispersion of the present invention. In Comparative Example 3Td, sedimentation was observed, but Comparative Examples 3Ta to c, Comparative Examples 3T′a to d, and Comparative Examples 3T ″ a to d did not sediment. However, the transparency was poor in Comparative Examples 3Ta to c, Comparative Examples 3T′a, Comparative Examples 3T′c to d, Comparative Examples 3T ″ a and Comparative Examples 3T ″ c to d of the nanoparticle dispersion. did. When the dispersibility was poor, the transparency of the nanoparticle dispersion was also low.

  Therefore, the comparative example of the nanoparticle body coated with the surfactant S0 or S10 has low transparency depending on the polarity of the organic solvent. On the other hand, in the Example of the nanoparticle body coat | covered with surfactant P12-10, P12-14, P8-10, or P16-10, transparency was high irrespective of the polarity of the organic solvent.

<Characteristics of nanoparticle dispersion: particle size distribution>
FIG. 22 is a particle size distribution diagram of Examples 1A′a to d of the nanoparticle dispersion of the present invention. In Examples 1A′a to d, it was confirmed that the titanium oxide nanoparticles were dispersed to near the primary particles.

  Example 1A, Example 1A ′, Example 1A ″, Example 1B, Example 1B ′, Example 1B ″, Example 1C, Example 1C ′, Example 1C ′ of the nanoparticle body of the present invention ', Example 1D, Example 1D', Example 1D ", Example 2A, Example 3A are excellent in dispersibility in both polar and nonpolar organic solvents. Although it is very difficult to redisperse a nanoparticle body prepared from a nanoparticle dispersion, according to these examples, redispersion is possible regardless of the polarity of the solvent. Moreover, it can be completely redispersed. It can be redispersed at a high concentration of 3 wt% and 10 wt% in an organic solvent.

  In the examples of the nanoparticle bodies coated with the surfactant P12-10, P12-14, or P8-10, the dispersibility was extremely high regardless of the polarity of the organic solvent, and the transparency was extremely high. Also in Examples of nanoparticle bodies coated with the surfactant P16-10, dispersibility became extremely high regardless of the polarity of the organic solvent after several days had passed after dispersion.

  Among the examples of nanoparticle bodies coated with the surfactant P12-10, P12-14, or P8-10, nanoparticles in which the amount of the surfactant is 2.0 mmol or more with respect to 1 g of titanium oxide. According to the example of the body, the example of the redispersed nanoparticle dispersion had extremely high dispersibility and transparency, and could be redispersed with about the primary particles.

  In the example of the nanoparticle body coated with the surfactant P12-10, the example of the redispersed nanoparticle dispersion was superior in terms of dispersibility and transparency. According to the example of the nanoparticle body in which the type of particles is titanium oxide, the example of the redispersed nanoparticle dispersion was not only transparent but also highly colorless.

  In the example of the nanoparticle body coated with the surfactant P12-10, even when the amount of the surfactant is 1.0 mmol with respect to 1 g of titanium oxide, it has extremely high dispersibility and transparency, and is about the primary particle. It could be redispersed.

  In the example of the nanoparticle body of the present invention, it can be dispersed regardless of the solvent to be redispersed, and the dispersibility is high in any solvent. It is a dispersion excellent in particle dispersion uniformity and has high transparency as well as uniformity. Therefore, application fields such as optical materials and cosmetics are widened.

  According to the examples of the nanoparticle body of the present invention, since all are dry powders, they are easily redispersed in another solvent. Moreover, handling and carrying become easy. Moreover, since the surface of the nanoparticle body is coated, it is well-organized even if it is dried, and the powder is not easily scattered. Therefore, it is excellent also in safety. Further, according to the above-described embodiment of the nanoparticle body of the present invention, the choice of solvent is widened, the convenience is very high, and it can be used in a wide field.

  According to the above-described embodiments of the nanoparticle body of the present invention, none of the conventional nanoparticle bodies can be used, or the nanoparticle can be used in fields where the functions could not be sufficiently exhibited.

  According to the method for producing a nanoparticle body of the present invention, the mixing property between the nanoparticles and the surfactant is improved, so that it is easy to uniformly coat the surfaces of the nanoparticles. In addition, the surface of the particles can be more uniformly coated with the surfactant. Moreover, since a nanoparticle body is obtained as a dry powder, it can be easily redispersed in another solvent. Moreover, handling and carrying become easy. Moreover, since the surface of the nanoparticle body is coated, it is well-organized even if it is dried, and the powder is not easily scattered. Therefore, it is excellent also in safety.

  According to the method for producing a nanoparticle dispersion of the present invention, a highly dispersible nanoparticle body having very little aggregation and having a hydrophobic group and a hydrophilic group on the surface is redispersed while preventing aggregation. Is uniformly dispersed in the dispersion. Moreover, the nanoparticle dispersion excellent in the dispersion uniformity of the nanoparticles in the dispersion can be obtained. Moreover, a highly transparent nanoparticle dispersion can be obtained.

<Composite material>
Example 1A′dF of the composite material of the present invention is a composite material of Example 1A ′ of the nanoparticle body and an epoxy resin, and was produced in detail as follows.

First, after adding a toluene solution of liquid epoxy resin (liquid epoxy 2.0 g + toluene 1.5 g) to Example 1A′d (particles 0.1056 g + toluene 3.50 g) of the nanoparticle dispersion of the present invention, Toluene was evaporated by an evaporator to prepare a liquid epoxy / TiO ₂ composite. Such a liquid epoxy / TiO ₂ composite showed high transparency. Next, 0.1 g of polyetherimide (PEI) is added to the liquid epoxy / TiO ₂ composite as a curing agent, mixed and vacuum degassed, and then at 120 ° C. for 2 hours and at 160 ° C. for 1 hour. By curing for 5 hours, an epoxy / TiO ₂ composite (5 wt%) as Example 1A′dF was obtained.

  FIG. 23 is a diagram showing the results of transparency observation of Example 1A′dF of the composite material of the present invention. FIG. 23 is a top view of a transparent container (sample bottle with a diameter of 18 mm) containing Example 1A′dF of the composite material, and the thickness of Example 1A′dF of the composite material is 3 mm. A board with a horizontal black pattern on a white background was placed below. Even through the 3 mm thick Example 1A'dF, the horizontal pattern of the board placed underneath was clearly visible. That is, Example 1A′dF of the composite material showed extremely high transparency. From the high transparency, it can be seen that the particles are very uniformly dispersed in Example 1A'dF.

  Since the composite material of Example 1A′dF of the present invention has transparency, it can be used in a wide range of fields such as optical materials.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. In addition, the constituent elements of the above embodiments can be arbitrarily combined without departing from the spirit of the invention.

  Prevents the agglomeration phenomenon in organic solvents, which is a problem when applying nanoparticles that can be synthesized in large quantities in recent years in various fields such as materials and pharmaceuticals, regardless of whether the solvent is polar or not. can do. It can be dispersed very uniformly in various solvents at the primary particle level. Therefore, it can be used in the fields of cosmetics, medicines, pigments, composite materials, optical materials, electromagnetic materials and the like. For example, when the nanoparticles are titanium oxide, an ink material that is expected to have high resolution by being uniformly dispersed, and an optical plastic lens and a pickup lens that are expected to have a high refractive index by being uniformly dispersed. It can be used for When the nanoparticles are iron oxide, it can be used as an electromagnetic wave absorber material that is expected to have high electromagnetic wave absorbing ability by being uniformly dispersed. When the nanoparticles are silver, they can be used for antibacterial materials and the like that are expected to have a large antibacterial action by being uniformly dispersed.

Claims (15)

The following chemical formula (1) is applied to the metal or metal oxide nanoparticles:
(Wherein, R ¹ is a hydrocarbon group of a saturated or unsaturated straight-chain or branched-chain having 1 to 3 carbon atoms, ^{R 2} is an alkyl group having 10 to 16 carbon atoms, n = 8 to 16 integer, m + k = 3 and m = 1 or 2, k = 1 or 2.)
A method for producing a nanoparticle body, wherein the surface is coated with a phosphate-based surfactant represented by the formula: The method for producing a nanoparticle body according to claim 1, wherein the metal or metal oxide nanoparticles are silver, titanium oxide, or iron oxide nanoparticles. The metal or metal oxide nanoparticles are titanium oxide nanoparticles, and the method includes a mixing step of mixing an aqueous solution containing the surfactant with an aqueous solution containing the nanoparticles. Item 3. A method for producing a nanoparticle according to Item 2. The method for producing a nanoparticle body according to claim 3, wherein in the mixing step, the amount of the surfactant is 1 mmol or more and 3 mmol or less with respect to 1 g of titanium oxide. The said nanoparticle is a single nanoparticle with an average particle diameter of 8 nm or less, The manufacturing method of the nanoparticle body of Claim 3 or Claim 4 characterized by the above-mentioned. The metal or metal oxide nanoparticles are iron oxide nanoparticles, and include a mixing step of mixing the surfactant in an aqueous solution in which an iron hydroxide aqueous solution is heated to generate iron oxide in the aqueous solution. The manufacturing method of the nanoparticle body of Claim 2 characterized by the above-mentioned. The metal or metal oxide nanoparticles are silver nanoparticles, and the method includes a mixing step of mixing an aqueous solution containing the surfactant and a reducing agent in an aqueous silver nitrate solution. The manufacturing method of the nanoparticle body of description. The following chemical formula (1) is applied to the metal or metal oxide nanoparticles:
(Wherein, R ¹ is a hydrocarbon group of a saturated or unsaturated straight-chain or branched-chain having 1 to 3 carbon atoms, ^{R 2} is an alkyl group having 10 to 16 carbon atoms, n = 8 to 16 integer, m + k = 3 and m = 1 or 2, k = 1 or 2.)
Nanoparticles characterized by being a powder having a surface coated with a phosphate-based surfactant represented by 9. The nanoparticle body according to claim 8, wherein the metal or metal oxide nanoparticles are titanium oxide, iron oxide, or silver nanoparticles. The nanoparticle body according to claim 9, wherein the metal or metal oxide nanoparticle is a titanium oxide nanoparticle and is a single nanoparticle having an average particle diameter of 8 nm or less. The nanoparticle according to any one of claims 8 to 10, which has a hydrophilic group having an affinity for a polar organic solvent and a hydrophobic group having an affinity for a nonpolar organic solvent on the particle surface. body. The nanoparticle body according to any one of claims 8 to 11, wherein the average aggregated particle diameter is dispersed at 200 nm or less with respect to both the nonpolar organic solvent and the polar organic solvent. A method for producing a nanoparticle dispersion, comprising a dispersion step of dispersing the nanoparticle body according to any one of claims 8 to 12 in a nonpolar organic solvent or a polar organic solvent. A nanoparticle dispersion comprising the nanoparticle body according to any one of claims 8 to 12 and a nonpolar organic solvent or a polar organic solvent. The nanoparticle dispersion according to claim 14, wherein the nanoparticle body has an average aggregate particle diameter of 200 nm or less in the dispersion.