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Powder, method of producing powder and adsorption apparatus

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Powder, method of producing powder and adsorption apparatus


The present invention provides that powder is mainly constituted from secondary particles of hydroxyapatite. The secondary particles are obtained by drying a slurry containing primary particles of hydroxyapatite and aggregates thereof and granulating the primary particles and the aggregates. A bulk density of the powder is 0.65 g/mL or more and a specific surface area of the secondary particles is 70 m2/g or more. The powder of the present invention has high strength and is capable of exhibiting superior adsorption capability when it is used for an adsorbent an adsorption apparatus has.
Related Terms: Hydroxyapatite

Browse recent Hoya Corporation patents - Tokyo, JP
Inventor: Shintaro Kobayashi
USPTO Applicaton #: #20120285880 - Class: 210263 (USPTO) - 11/15/12 - Class 210 
Liquid Purification Or Separation > Particulate Material Type Separator, E.g., Ion Exchange Or Sand Bed

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The Patent Description & Claims data below is from USPTO Patent Application 20120285880, Powder, method of producing powder and adsorption apparatus.

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TECHNICAL FIELD

The present invention relates to powder, a method of producing powder, and an adsorption apparatus.

RELATED ART

Hydroxyapatite has high biocompatibility, high safety and the like. For these reasons, in recent years, the hydroxyapatite has been used generally as a material for stationary phase of a chromatography which is used when a bio medicine such as an antibody and a vaccine is purified and isolated.

As described above, the hydroxyapatite is used as the material for stationary phase of the chromatography, which can be produced as follows.

First, a first liquid containing calcium hydroxide is mixed with a second liquid containing phosphoric acid to obtain a mixture. Then, the calcium hydroxide is reacted with the phosphoric acid with stirring the mixture to obtain a slurry containing primary particles of hydroxyapatite and aggregates thereof. Next, the slurry containing the primary particles and the aggregates thereof is dried. Then, the dried primary particles and aggregates are granulated to thereby obtain secondary particles (powder) of the hydroxyapatite.

Next, the powder is sintered to obtain sintered powder (hereinafter, referred to as “sintered powder”). The powder and the sintered powder are filled in a column (absorption apparatus) as a material for stationary phase (adsorbent) (see Patent Document 1).

In the reaction to obtain the hydroxyapatite by using such calcium hydroxide and phosphoric acid, by-products other than the hydroxyapatite are only water. Therefore, there is an advantage that no by-products remain in the formed powder and the sintered powder. Further, there is also an advantage that the reaction is controlled with ease by adjusting pH of the first liquid and the second liquid. This is because the reaction is an acid-base reaction.

However, in such a method, the calcium hydroxide has low solubility to the first liquid. Due to the fact, the reaction of the calcium hydroxide and phosphoric acid becomes a solid-liquid reaction. Therefore, the aggregates of the primary particles formed in the slurry are non-uniform in an agglomeration degree thereof.

If powder of hydroxyapatite is obtained by drying a slurry in a state of the non-uniform aggregates in such an agglomeration degree, there is a problem in that the powder cannot obtain sufficient strength due to a low bulk density of the powder. Further, when the powder is used as a material for stationary phase, there is also a problem in that the material for stationary phase cannot exhibit superior adsorption capability because a specific surface area of particles of the powder becomes low. In this regard, it is to be noted that a particle in this specification means each of particles (secondary particles) and powder in this specification means that a plurality of particles gathered together.

In particular, such problems are caused more conspicuously when powder of particles having a particle size of 10 μm or less is used for the material for stationary phase.

In order to solve the problems, there is known a method of obtaining spherical hydroxyapatite particles by spraying a slurry of hydroxyapatite into a plasma generation apparatus and then heating the sprayed slurry at a temperature of several thousand degree. However, in such a method, phosphoric acid is volatilized at a high temperature so that an amount of calcium becomes excess. Therefore, particles which have no apatite structure and do not have a constant composition are obtained. Such particles are not suitable as a material for stationary phase.

The Patent document 1 is JP-A 03-218460.

SUMMARY

OF THE INVENTION

It is an object of the present invention to provide powder that has high strength and is capable of exhibiting excellent adsorption capability when it is used for an adsorbent used in an adsorption apparatus. Furthermore, it is another obj ect of the present invention to provide a method of producing powder that can produce such powder and an adsorption apparatus that uses such powder as an adsorbent.

These objects are achieved by the present inventions (1) to (10) described below.

(1) Powder including hydroxyapatite, wherein the hydroxyapatite includes primary particles and secondary particles obtained by drying a slurry containing the primary particles and aggregates thereof and granulating the primary particles and the aggregates, and the powder comprising: mainly the secondary particles of the hydroxyapatite, wherein a bulk density of the powder is 0.65 g/mL or more and a specific surface area of the secondary particles is 70 m2/g or more.

The powder, which has the bulk density within such a range and the particles having the specific surface area within such a range, has high strength and are capable of exhibiting excellent adsorption capability when it is used for an adsorbent used in an adsorption apparatus.

(2) In the method described in the above-mentioned item (1), a sphericity of each of the secondary particles of the powder is in the range of 0.95 to 1.00.

When the powder including the particles having high sphericity is used as an adsorbent used in an adsorption apparatus, it is possible to improve a filling ratio of the powder into an adsorbent filling space of the adsorption apparatus.

(3) In the method described in the above-mentioned item (1) or (2), the secondary particles consisting the powder are classified so as to have an average particle size of 40±4 μm, wherein when a repose angle of the powder constituted of the classified secondary particles is measured, the repose angle is 27° or lower.

The powder having a low repose angle has a high flowability. Therefore, when the powder is used as an adsorbent used in an adsorption apparatus, it is possible to improve a filling efficiency of filling the powder into an adsorbent filling space of the adsorption apparatus.

(4) In the method described in the above-mentioned items (1) to (3), the powder is sintered at a temperature of 700° C. to obtain sintered powder having particles, and then the particles of the sintered powder are classified so as to have an average particle size of 40+4 μm, wherein when a compressive particle strength of the classified particles is measured, the compressive particle strength is over 9.0 MPa.

The powder comprised of the particles having the compressive particle strength within such a range can have sufficiently strength when it is used as an adsorbent used in an adsorption apparatus.

(5) In the method described in the above-mentioned items (1) to (4), the powder is sintered at a temperature of 700° C. to obtain sintered powder including particles each having a surface and micropores formed on the surface, wherein an average pore size of the micropores is 0.07 μm or less.

This makes it possible to reliably increase the specific surface area of the particles of the sintered powder.

(6) In the method described in the above-mentioned items (1) to (5), an average particle size of the secondary particles of the powder is in the range of 2 to 100 μm.

The powder of the particles having such an average particle size is preferably used to the present invention. When the powder is used for an adsorbent used in an adsorption apparatus, the powder exhibits high strength and excellent adsorption capability.



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stats Patent Info
Application #
US 20120285880 A1
Publish Date
11/15/2012
Document #
13497635
File Date
09/22/2010
USPTO Class
210263
Other USPTO Classes
423308, 428402, 2105021
International Class
/
Drawings
8


Hydroxyapatite


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