JP5339020B2 - Method for producing dispersion of inorganic particles - Google Patents

Description

  In the present invention, the inorganic particle powder is uniformly dispersed as nano-order fine particles having a narrow particle size distribution in the dispersion medium, and does not cause thickening, gelation, sedimentation separation, etc. during long-term storage. The present invention relates to a method for producing a dispersion of inorganic particles having excellent stability.

  When the particle diameter of the inorganic particle powder is refined to 100 nm or less in the dispersion medium, the dispersion exhibits characteristics similar to those of a solution, but the same substance but different characteristics from the bulk develop. Utilizing the features, it will be possible to manufacture functional materials such as functional inks, paints, pharmaceuticals, and agricultural chemicals, starting with advanced technology industries such as electronics and photonics. In addition, when the particle size of the inorganic particle powder is sufficiently smaller than the wavelength in the visible region, the light scattering intensity is significantly reduced and the transparency is increased. It is attracting widespread attention.

  Several methods have been proposed so far to make the inorganic particle powder into fine particles, but they are roughly divided into two methods, a build-up method and a breakdown method.

  The build-up method that assembles atoms and molecules to make particles is generally more pure than the breakdown method and is suitable for producing nano-order fine particles. For example, inorganic particle powder is dissolved in a solvent. Then, it is difficult to scale up because of complicated operations such as precipitation and concentration in a poor solvent by a method such as precipitation and concentration, and precise control may be necessary. Further, since the obtained nanoparticles have a very large surface energy, the nanoparticles aggregate with each other, making it difficult to obtain nano-order fine particles.

  On the other hand, in the breakdown method in which large particles are crushed, the inorganic particle powder is mechanically pulverized or ground, and these include a wet method using a liquid as a dispersion medium and a dry method without using a dispersion medium. Both are widely used because they provide a process that can be produced at low cost and in large quantities. However, there is a limit to the size of the particle diameter obtained by mechanical pulverization, and since the particle size distribution of the particle diameter is wide, there remains a problem in the formation of fine particles on the nano order. Further, when excessive grinding is performed, it is difficult to stably generate nano-order fine particles by reaggregation of the pulverized particles due to an increase in activity of the generated particle surface. In addition, in long-term storage, nanoparticles are aggregated during storage for the reasons described above, and the dispersion of inorganic particles thickens or gels, or the aggregated nanoparticles precipitate and separate. May occur.

  So far, with respect to these problems of the breakdown method, there has been proposed a dispersion method (Patent Document 1) using a medium stirring type disperser and 200 to 10,000 times the aggregated particles dispersed as stirring particles. Yes.

  As a method for dispersing silica in an aqueous medium, a production method (Patent Document 2) in which two dispersion steps, a preliminary dispersion step and a main dispersion step, are proposed.

JP 2005-87972 A Japanese Patent Laid-Open No. 10-310415

  Inorganic particle powder is uniformly dispersed as nano-order fine particles with a narrow particle size distribution in the dispersion medium, and does not cause thickening, gelation or sedimentation separation during long-term storage, and has excellent storage stability A method for producing a dispersion of inorganic particles is currently most demanded, but has not yet been obtained.

  That is, Patent Document 1 describes a dispersion method using a medium stirring type disperser and 200 to 10,000 times the aggregated particles dispersed as stirring particles. Since no further dispersion has been performed after finely dispersing to the order particle size, the nano-order fine particles pulverized by dispersion are aggregated during storage, resulting in a dispersion of inorganic particles having excellent storage stability. It is difficult to obtain.

  In addition, Patent Document 2 describes a production method in which two dispersion steps, a preliminary dispersion process and a main dispersion step, are provided as a method for dispersing silica in an aqueous medium. Since further dispersion is not performed after finely dispersing to a nano-order particle size, it is difficult to obtain a dispersion of inorganic particles having excellent storage stability.

  Therefore, the present invention uniformly disperses the inorganic particle powder as nano-order fine particles having a narrow particle size distribution in the dispersion medium, and does not cause thickening, gelation, sedimentation separation, etc. during long-term storage. An object of the present invention is to provide a method for producing a dispersion of inorganic particles having excellent storage stability.

  The technical problem can be achieved by the present invention as follows.

  That is, the present invention provides a first step of predispersing an inorganic particle powder having an average primary particle size of 100 nm or less in a dispersion medium, and a dispersion medium containing the inorganic particle powder obtained in the first step as a medium. And a second step of dispersing with stirring and a third step of post-dispersing the dispersion medium containing the inorganic particle powder obtained in the second step. (Invention 1).

  Moreover, this invention is a manufacturing method of the dispersion | distribution of the inorganic particle of this invention 1 characterized by the average particle diameter of the medium used at a 2nd process being less than 100 micrometers. (Invention 2).

  According to the present invention, the inorganic particle powder is uniformly dispersed as nano-order fine particles having a narrow particle size distribution in the dispersion medium, and does not cause thickening, gelation, sedimentation separation, etc. during long-term storage. In addition, a dispersion of inorganic particles having excellent storage stability can be obtained.

  Below, the manufacturing method of the dispersion of the inorganic particle which concerns on this invention is described.

  The method for producing a dispersion of inorganic particles according to the present invention includes a first step of pre-dispersing an inorganic particle powder having an average primary particle size of 100 nm or less in a dispersion medium, and an inorganic material obtained in the first step. It comprises a second step of stirring and dispersing the dispersion medium containing the particle powder together with the medium, and a third step of post-dispersing the dispersion medium containing the inorganic particle powder obtained in the second step.

As the inorganic particle powder in the present invention, SiO ₂ , TiO ₂ , BaTiO ₃ , ITO (indium tin oxide), ATO (antimony tin oxide), SnO ₂ , Fe ₂ O ₃ , α-FeOOH, ZrO ₂ , CeO Metal oxides such as MoO and Al ₂ O ₃ and hydrous oxides, metals such as Fe, Cu, Ag, Au, and Ni, and inorganic powders such as carbon black can be used.

  The average primary particle diameter of the inorganic particle powder in the present invention is 100 nm or less.

The BET specific surface area value of the inorganic particle powder in the present invention is 5 m ² / g or more.

  As the dispersion medium in the present invention, either an aqueous system or a solvent system can be used.

  As a dispersion medium of the aqueous dispersion, water or alcohol solvents such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, and butyl alcohol; glycol ether solvents such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, and butyl cellosolve; Oxyethylene or oxypropylene addition polymers such as diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; alkylene glycols such as ethylene glycol, propylene glycol, and 1,2,6-hexanetriol; glycerin Water-soluble organic solvents such as 2-pyrrolidone can be used. These dispersion media for aqueous dispersions can be used alone or in combination of two or more according to the intended dispersion.

  Dispersion media for solvent-based dispersions include aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone Ether glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl Ether acetates such as ether acetate and propylene glycol monoethyl ether acetate; ethyl acetate Butyl acetate, esters such as isobutyl acetate; methyl lactate ester, ethyl lactate esters, lactate esters such as lactic acid propyl ester, ethylene carbonate, propylene carbonate, and cyclic esters such as γ- butyrolactone. These dispersion media for solvent-based dispersions can be used alone or in combination of two or more depending on the intended dispersion.

  The disperser used in the first step of predispersing the inorganic particle powder of the present invention in a dispersion medium is not particularly limited, but a shearing force, impact force, compressive force, and / or frictional force is applied to the powder layer. An apparatus capable of handling is preferable. For example, a roller mill, a high-speed rotary mill, a high-speed rotary mill with a built-in classifier, a ball mill, a medium agitation mill, an airflow-type pulverizer, a compaction shear mill, a colloid mill, a roll mill, etc. .

  When using a media agitating mill in the first step, the grinding media may be stainless steel, steel ball beads such as steel, depending on the mill material; alumina, steatite, zirconia, zircon, silica, silicon carbide, nitriding Ceramic beads such as silicon; glass beads such as soda glass and high bee; carbide beads such as WC can be used, and the size is preferably in the range of 0.1 to 1.5 mm.

  As the disperser used in the second step of stirring and dispersing the dispersion medium containing the inorganic particle powder obtained in the first step of the present invention together with the medium, a medium stirring mill can be suitably used. A vertical bead mill is preferred.

  As the grinding media used in the second step, depending on the mill material, steel ball beads such as stainless steel and steel; ceramic beads such as alumina, steatite, zirconia, zircon, silica, silicon carbide, and silicon nitride; soda Glass beads such as glass and high bee; carbide beads such as WC can be used, the size is less than 100 μm, and the lower limit is 1 μm.

As the disperser used in the third step of post-dispersing the dispersion medium containing the inorganic particle powder obtained in the second step of the present invention, it is preferable to use other than a medium stirring mill, particularly preferably an ultrasonic type. A disperser can be used.

  The dispersion of inorganic particles obtained by the production method of the present invention contains 1 to 80 parts by weight, preferably 3 to 70 parts by weight, more preferably 5 parts, of inorganic particle powder with respect to 100 parts by weight of the dispersion-constituting substrate. Contains 60 parts by weight. As a constituent substrate of the dispersion of inorganic particles, in addition to the above inorganic particle powder, it is made of a dispersion medium, and if necessary, a dispersant, an additive (resin, antifoaming agent, auxiliary agent, etc.) and the like are added. You can also.

  As the dispersant in the present invention, it can be appropriately selected and used according to the kind of inorganic particles and dispersion medium to be used. Organosilicon compounds such as alkoxysilane, silane coupling agent and organopolysiloxane, surface activity An agent or a polymer dispersant can be used, and these can be used alone or in combination of two or more.

  Examples of the organosilicon compound include methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, hexyltriethoxysilane, and octyltriethoxy. Silanes, alkoxysilanes such as tetraethoxysilane and tetramethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane Emissions, .gamma.-chloropropyl trimethoxy silane silane coupling agent such as a polysiloxane, methyl hydrogen polysiloxane, organopolysiloxane and the like of the modified polysiloxane.

  Examples of the surfactant include anionic surfactants such as fatty acid salts, sulfate ester salts, sulfonate salts and phosphate ester salts; polyethylene glycol type nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene aryl ethers Agents, nonionic surfactants such as polyhydric alcohol type nonionic surfactants such as sorbitan fatty acid esters; chaotic surfactants such as amine salt type cationic surfactants and quaternary ammonium salt type cationic surfactants Agents: amphoteric surfactants such as alkylbetaines such as alkyldimethylaminoacetic acid betaine and alkylimidazolines.

  As the polymer dispersant, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, polycarboxylic acid, its salt, and the like can be used.

  The amount of the dispersant added depends on the total surface area of the inorganic particle powder in the dispersion and may be appropriately adjusted depending on the use of the inorganic particle dispersion and the type of the dispersant. By adding 0.01 to 100% by weight of a dispersant to the inorganic particle powder in the medium, the inorganic particles can be dispersed uniformly and finely in the dispersion medium, and the dispersion stability can be improved. it can. In addition to adding the dispersant directly to the dispersion medium, the dispersant may be previously treated with inorganic particles.

  The number-average dispersed average particle diameter of the inorganic particles in the inorganic particle dispersion obtained by the production method of the present invention is 100 nm or less, preferably 90 nm, more preferably, although it depends on the average primary particle diameter of the inorganic particles. 80 nm or less.

The dispersion reach in the dispersion of inorganic particles obtained by the production method of the present invention is 1.50 or less as a ratio of the number-average dispersed average particle diameter of inorganic particles to the average primary particle diameter of inorganic particles, preferably 1.45 or less, more preferably 1.40 or less.

  The particle size distribution of the inorganic particles in the dispersion of inorganic particles obtained by the production method of the present invention is preferably 2.0 or less, more preferably 1.8 as the geometric standard deviation value of the volume-dispersed dispersion average particle diameter. Hereinafter, it is still more preferably 1.6 or less.

  The dispersion stability of the dispersion of inorganic particles obtained by the production method of the present invention is preferably 3, 4 or 5 when the degree of sedimentation of the particle powder is evaluated visually among the evaluation methods described below. Preferably 4 or 5. Further, the rate of change in viscosity is preferably 10% or less, more preferably 8% or less. When the degree of sedimentation of the particle powder is evaluated visually, it becomes 1 or 2, or when the rate of change in viscosity is more than 10%, it becomes difficult to store for a long time in a stable dispersion state.

  Hereinafter, the present invention will be described in detail with reference to examples.

  The average particle diameter of the primary particles of the inorganic particle powder was measured by measuring the particle diameters of 350 particles shown in the electron micrograph, and the average particle diameter was indicated.

  The specific surface area value was indicated by a value measured by the BET method.

  The number-converted average particle diameter and volume-converted average particle diameter of the inorganic particles in the dispersion medium were measured using a dynamic light scattering method “Dense System Particle Size Analyzer FPAR-1000” (Otsuka Electronics Co., Ltd.).

  The degree of achievement of the dispersion of the inorganic particles in the dispersion was represented by the ratio of the number-average dispersed average particle diameter of the inorganic particles to the average primary particle diameter of the inorganic particles.

  The particle size distribution of the inorganic particles in the inorganic particle dispersion was indicated by the geometric standard deviation value determined by the following method.

  That is, the particle diameter on the logarithmic normal probability paper on the logarithmic normal probability paper and the vertical axis belongs to each of the predetermined particle diameter sections according to a statistical method from the volume-converted dispersed particle diameter and number measured using the dynamic light scattering method. Plot the cumulative number of particles (under integrated sieve) as a percentage. Then, from this graph, the particle diameter values corresponding to the number of particles of 50% and 84.13% are read, and the geometric standard deviation value = particle diameter under integrated fluid 84.13% / under integrated fluid 50%. The value was calculated according to the particle diameter (geometric mean diameter). The closer the geometric standard deviation value is to 1, the better the particle size distribution of the inorganic particles in the inorganic particle dispersion.

  The dispersion stability of the inorganic particle dispersion was determined by putting 25 ml of the dispersion into a 50 ml colorimetric tube and allowing it to stand at 60 ° C. for 4 weeks. Evaluation was performed.

1: The non-colored part is 10 cm or more.
2: The non-colored part is 5 cm or more and less than 10 cm.
3: The non-colored part is 1 cm or more and less than 5 cm.
4: The non-colored part is less than 1 cm.
5: A non-colored part is not recognized.

The viscosity change rate of the dispersion of inorganic particles was determined by using the “E-type viscometer EMD-R” (manufactured by Tokyo Keiki Co., Ltd.) at 25 ° C. after allowing the obtained dispersion to stand at 60 ° C. for 1 week. The viscosity value at shear rate D = 383 sec ⁻¹ was measured, and the value obtained by dividing the amount of change in viscosity before and after standing by the value before standing was shown as a percentage as the rate of change.

<Example 1: Production of dispersion of inorganic particles>
In a horizontal bead mill (“DISPERMAT SL603” manufactured by VMA-Getzmann, glass media (particle size: 1 mm) is placed so as to be 80 vol% of the stirring vessel, and then inorganic particles 1 (type: silica, average primary particle size: 13.8 nm, BET specific surface area value: 200.4 m ² / g) 280 g, a solution in which Solsperse 32500 (manufactured by Nippon Lubrizol Co., Ltd.) 120 g and PGMEA 1600 g as a dispersing agent was circulated and dispersed for 4 hours to obtain inorganic particles. A first step dispersion was obtained.

  Next, glass media (particle size 50 μm) is placed in a zirconia 0.5 liter stirring vessel of a vertical bead mill (“Ultra Apex Mill UAM-05” manufactured by Kotobuki Giken Kogyo Co., Ltd.) so that the volume becomes 70 vol% of the stirring vessel. Then, the first step dispersion obtained above was dispersed for 1 hour while circulating to obtain a second step dispersion of inorganic particles.

  Furthermore, the dispersion obtained in the second step was put in an ultrasonic disperser (“Sonifier II Model 450D” manufactured by BRANSON) and dispersed for 10 minutes to obtain a dispersion of inorganic particles.

  The number-average dispersed particle diameter of the inorganic particles in the obtained inorganic particle dispersion is 18.1 nm, and the degree of dispersion reach in the inorganic particle dispersion is determined by the number-average dispersed average particle diameter of the inorganic particles and the inorganic particles. The average primary particle size ratio is 1.31, the particle size distribution of the inorganic particles in the dispersion of inorganic particles is 1.22 in terms of geometric standard deviation, the dispersion stability is 5, and the rate of change in viscosity is 3.8%. there were.

  According to Example 1, a dispersion of inorganic particles was prepared. Various production conditions and various properties of the obtained dispersion of inorganic particles are shown.

Inorganic particles 1 to 4:
As the inorganic particle powder, inorganic particles 1 to 4 having the characteristics shown in Table 1 were prepared.

<Production of dispersion of inorganic particles>
Examples 1-4, Comparative Example 1:
Type and amount of inorganic particle powder in the first step, type of disperser and dispersion medium, type and amount of dispersion medium, type and amount of dispersant, type of dispersion medium in the second step, in step 3 A dispersion of inorganic particles was obtained in the same manner as in Example 1 except that the type of the disperser was variously changed.

  The production conditions at this time are shown in Table 2, and the properties of the obtained dispersion of inorganic particles are shown in Table 3.

The dispersion of inorganic particles obtained by the production method of the present invention is used for functional materials such as commonly used paints, printing inks, etc., electronics, photonics, functional inks, paints, pharmaceuticals, agricultural chemicals, etc. can do.

Claims (1)

A first step of pre-dispersing inorganic particle powder having an average primary particle size of 100 nm or less in a dispersion medium using a medium stirring mill, and a dispersion medium containing the inorganic particle powder obtained in the first step A second step of stirring and dispersing together with a medium having an average particle diameter of less than 100 μm, and a dispersion medium containing the inorganic particle powder obtained in the second step is post-dispersed using an ultrasonic disperser; A method for producing a dispersion of inorganic particles, comprising three steps.