JP4281893B2 - Porous non-conductive ceramic particles with improved fluidity and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to porous non-conductive ceramic particles and a method for producing the same, and more particularly to porous non-conductive ceramic particles having improved flowability in a simple manner without affecting the properties of the porous non-conductive ceramic particles themselves, and The manufacturing method.
[0002]
[Prior art]
Porous ceramics have various properties and functions such as light weight, heat insulation, sound absorption, adsorptivity, separation function and selective permeation function in addition to the inherent heat resistance and chemical resistance of ceramics. Therefore, its application is expanding in various fields.
[0003]
For example, porous calcium phosphate compounds represented by porous hydroxyapatite are excellent in biocompatibility, and are used as biomaterials such as artificial tooth roots, bone reinforcing materials, and dental cements. When porous hydroxyapatite is used as a biomaterial, it is usually formed into a molded body as a uniform mixture of a binder resin or the like in addition to a sintered body (for example, JP-A 2000-335962). In either case, porous hydroxyapatite is used in the form of particles.
[0004]
In addition to hydroxyapatite, there are various ceramics that can be used as porous ceramic particles. For example, in the case of alumina, (1) the pore distribution is uniform, and (2) the affinity with microorganisms is good. (3) Recyclable, (4) High mechanical strength, (5) Excellent chemical resistance, etc., so water treatment multifunctional ceramics, catalyst carrier, sensor substrate, composite material It is used for bioreactors, microbial carriers, adsorbents, hybrid materials, filter materials and the like. In addition, porous silica is also used as a chromatographic column filler in addition to the same applications as described above.
[0005]
However, since the porous ceramic particles as described above are generally non-conductive, they tend to be charged as a powder during handling and the particles are aggregated. When the particles are aggregated, there is a risk of blocking the transport path of the ceramic particles and the opening of the hopper of the molding machine. Therefore, it is desired to prevent the ceramic particles from being charged so that they can be easily handled.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide porous non-conductive ceramic particles having improved fluidity by preventing aggregation due to charging, and a method for producing the same.
[0007]
[Means for Solving the Problems]
As a result of intense research in view of the above object, the present invention have found that by impregnating the non-ionic surfactant into the pores of the porous non-conductive ceramic particles, the particles no longer charged aggregate, have fluidity improvement The present invention was conceived.
[0008]
That is, the porous non-conductive ceramic particles of the present invention are impregnated with a nonionic surfactant, have a sphericity of 0.7 or more and a moisture content of 10% or less. .
[0009]
The porous non-conductive ceramic particles of the present invention preferably have a porosity of 10 to 70%, and preferably have an average particle size of 50 to 500 μm.
[0010]
In the porous nonconductive ceramic particles of the present invention, the water content after impregnation with the nonionic surfactant is preferably 0.5 to 3% by weight higher than the water content before the impregnation.
[0011]
The porous non-conductive ceramic particles of the present invention are preferably made of porous hydroxyapatite.
[0012]
(Delete)
[0013]
The method for producing porous nonconductive ceramic particles of the present invention is characterized in that the porous nonconductive ceramic particles are impregnated with a nonionic surfactant to prevent aggregation of the particles.
[0014]
The nonionic surfactant is preferably brought into contact with the porous nonconductive ceramic particles in a solution having a concentration of 0.05 to 5% by weight. Moreover, it is preferable to set the impregnation amount of the nonionic surfactant so that the water content after impregnation with the nonionic surfactant is 0.5 to 3% by weight higher than the water content before impregnation.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
[0016]
[1] Porous non-conductive ceramic particles (1) Porous non-conductive ceramic particles The porous non-conductive ceramic particles for improving fluidity according to the present invention have a sphericity of 0.7 or more and 10 to 70%. And a mean particle size of 50 to 500 μm.
[0017]
The sphericity of ceramic particles is closely related to the fluidity of the particles. Accordingly, the sphericity is preferably 0.7 or more. Here, the sphericity is obtained by a circularity coefficient (4π × area / perimeter ² ). If the sphericity is less than 0.7, sufficient fluidity cannot be obtained even if the porous non-conductive ceramic particles are treated with a surfactant.
[0018]
The porosity of the porous non-conductive ceramic particles to which the present invention can be applied is preferably in the range of 10 to 70%. When the porosity is less than 10%, not only the characteristics as porous ceramic particles can be exhibited, but even when impregnated with a surfactant, it cannot be sufficiently supported in the pores. On the other hand, when the porosity exceeds 70%, not only the particle strength is excessively lowered, but it is difficult to ensure the sphericity. The porosity can be measured by a mercury porosimeter method.
[0019]
The average particle diameter of the porous non-conductive ceramic particles to which the present invention can be applied is preferably 50 to 500 μm, and more preferably 100 to 500 μm. If the average particle size is less than 50 μm, it tends to atomize during flow. On the other hand, if the average particle size exceeds 500 μm, it becomes difficult to ensure uniformity when the ceramic particles are press-molded or blended with a resin. In addition, an average particle diameter is the value which averaged the particle diameter calculated | required by the laser diffraction method about 1000 particles.
[0020]
The porous non-conductive ceramic particles satisfying the above conditions may be made of any ceramic as long as it is a non-conductive ceramic. can do.
[0021]
The Ca / P weight ratio of the calcium phosphate ceramic is preferably 1.6 to 1.7. When the Ca / P weight ratio is less than 1.6, it becomes a mixed phase with tricalcium phosphate [Ca ₃ (PO ₄ ) ₂ ], and when it exceeds 1.7, the mixed phase with calcium oxide (CaO) Become. A preferred example of the porous calcium phosphate ceramic to which the present invention is applied is porous hydroxyapatite [Ca ₁₀ (PO ₄ ) _6. (OH) ₂ ].
[0022]
The porous non-conductive ceramic particles are preferably secondary particles in which fine primary particles are aggregated. The secondary particles are preferably those granulated by a spray drying granulation method or the like from the viewpoint of easy control of sphericity, porosity and average particle size.
[0023]
(2) Surfactant The surfactant to be impregnated into the pores of the porous non-conductive ceramic particles is any of a nonionic surfactant, a cationic surfactant, an anionic surfactant and an amphoteric surfactant. However, a nonionic surfactant is preferable from the viewpoint of antistatic properties.
[0024]
Nonionic surfactants include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether (for example, polyoxyethylene octyl phenyl ether), glycerin fatty acid partial ester, sorbitan fatty acid moiety Examples thereof include esters, pentaerythritol fatty acid partial esters, polyoxyethylene sorbitan acid fatty partial esters, polyoxyethylene alkyl ether carboxylates, and fatty acid alkanolamides (for example, N, N-dimethyldodecylamine oxide).
[0025]
Examples of the cationic surfactant include alkylamine salts and dialkylamine salts.
[0026]
Examples of anionic surfactants include dialkyl sulfosuccinates, alkane sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, alkyl phosphate ester salts, polyoxyethylene alkyl ethers. Examples thereof include phosphoric acid ester salts, sulfuric acid ester salts of fatty acid alkyl esters, alkyl sulfuric acid ester salts, polyoxyethylene alkyl ether sulfuric acid ester salts, fatty acid monoglyceride sulfuric acid ester salts, and the like.
[0027]
Examples of amphoteric surfactants include N, N, N-trialkyl-N-sulfoalkylene ammonium betaine.
[0028]
(3) Impregnation of surfactant The amount of the surfactant impregnated in the porous non-conductive ceramic particles is such that the water content after impregnating the surfactant is 0.5 to 3% by weight higher than the water content before impregnation. It is preferable to set as follows. The amount of the surfactant impregnated to obtain such a moisture content is generally 0.0025 to 0.3 parts by weight, preferably 0.005 to 100 parts by weight per 100 parts by weight of the porous non-conductive ceramic particles. 0.05 parts by weight. If the surfactant is less than the lower limit, the effect of improving the fluidity due to impregnation is insufficient, and even if the upper limit is exceeded, no improvement in the effect commensurate with it is obtained.
[0029]
[2] Fluidization treatment method The method of impregnating the porous non-conductive ceramic particles with the surfactant is not limited, and a method of immersing the surfactant solution, a method of spraying, and the like can be used. “Impregnation” means that the surfactant is retained not only on the surface but also in the pores.
[0030]
The surfactant solution impregnated in the ceramic particles is preferably at a concentration of 0.05 to 5% by weight. If the concentration is less than 0.05% by weight, a sufficient amount of surfactant cannot be impregnated, and even if the concentration exceeds 5% by weight, no further improvement in fluidity can be obtained. In view of ease of treatment, the surfactant solution is preferably an aqueous solution.
[0031]
The porous non-conductive ceramic particles impregnated with the surfactant solution are heated to an appropriate temperature and sufficiently dried. In order to ensure sufficient fluidity, the water content of the porous non-conductive ceramic particles supporting the surfactant is preferably 10% or less.
[0032]
【Example】
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
[0033]
Example 1
As porous non-conductive ceramic particles, porous hydroxyapatite particles having a sphericity of 0.8, a porosity of 50%, an average particle size of 110 μm, a maximum particle size of 300 μm by classification, and a moisture content (loss on drying) of 4% by weight used. A 0.1% by weight aqueous solution of polyethylene glycol mono-p-iso-octylphenyl ether (trade name “Triton X-100”) as a nonionic surfactant was sprayed on the particles. Before and after spraying with the surfactant, the ceramic particles were heated at 200 ° C. for 2 hours, and the loss on drying in each case was measured. Since the respective weight loss was 4% by weight and 5.1% by weight, the increment of water content by spraying was 1.1% by weight. The porous hydroxyapatite particles impregnated with the surfactant were smooth.
[0034]
In order to evaluate the fluidity of the porous hydroxyapatite particles impregnated with the surfactant, the glass cylinder 1 having an inner diameter of 20 mm shown in FIG. 1 was used. The glass cylinder 1 includes an upper portion 1a, a lower portion 1b, and a reduced diameter portion 1c that connects the two, and an orifice 2 having an inner diameter D of 1.0 mm is provided at the center of the reduced diameter portion 1c.
[0035]
Porous hydroxyapatite particles 3 impregnated with a surfactant were placed in the upper part 1a of the glass cylinder 1, and naturally dropped by gravity onto the lower part 1b through the orifice 2. When the fluidity of the particles 3 was evaluated in this state, the clogging of the particles 3 at the orifice 2 did not occur even after 3 minutes had passed.
[0036]
Comparative Example 1
Dense hydroxyapatite particles (sphericity 0.8, average particle size 110 μm, maximum particle size 300 μm by classification) were sprayed with a 0.1 wt% aqueous solution of Triton X-100 as a nonionic surfactant. After spraying, the dense hydroxyapatite particles were left in the atmosphere and dried completely. When the fluidity of the dense hydroxyapatite particles coated with the surfactant was evaluated with the glass cylinder 1 shown in FIG. 1, the orifice 2 was clogged in 5 seconds.
[0037]
Comparative Example 2
The glass cylinder shown in FIG. 1 without applying a nonionic surfactant to the same dense hydroxyapatite particles as in Comparative Example 1 (sphericity 0.8, average particle size 110 μm, maximum particle size 300 μm by classification) When the fluidity was evaluated with 1, the orifice 2 was clogged in 5 seconds.
[0038]
【The invention's effect】
As described above, by impregnating with the nonionic surfactant according to the present invention, the porous non-conductive ceramic particles are not charged during the flow, so that the good fluidity can be maintained. The porous non-conductive ceramic particles subjected to the treatment of the present invention are suitable for transportation by a pipe or the like.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a glass cylinder for evaluating the fluidity of porous non-conductive ceramic particles.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Glass cylinder 1a ... Upper part 1b ... Lower part 1c ... Reduced diameter part 2 ... Orifice

Claims (8)

A porous non-conductive ceramic particle , impregnated with a nonionic surfactant, having a sphericity of 0.7 or more and a water content of 10% or less . The porous non-conductive ceramic particle according to claim 1 , wherein the porosity is 10 to 70%. The porous nonconductive ceramic particles according to claim 1 or 2 , wherein the average particle size is 50 to 500 µm. The porous nonconductive ceramic particles according to any one of claims 1 to 3 , wherein the water content after impregnation with the nonionic surfactant is 0.5 to 3% by weight higher than the water content before impregnation. Porous non-conductive ceramic particles characterized. The porous nonconductive ceramic particle according to any one of claims 1 to 4 , wherein the ceramic particle is made of porous hydroxyapatite. The method for producing porous nonconductive ceramic particles according to any one of claims 1 to 5 , wherein the porous nonconductive ceramic particles are impregnated with a nonionic surfactant to aggregate the particles. A method characterized by preventing. 7. The method for producing porous nonconductive ceramic particles according to claim 6 , wherein the nonionic surfactant is brought into contact with the porous nonconductive ceramic particles in a solution having a concentration of 0.05 to 5% by weight. A method characterized by letting go. The method for producing porous nonconductive ceramic particles according to claim 6 or 7 , wherein the water content after impregnation with the nonionic surfactant is 0.5 to 3% by weight higher than the water content before impregnation. And setting an impregnation amount of the nonionic surfactant.

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