JPH0780281A - Production of ceramic hollow particles - Google Patents

Abstract

PURPOSE:To produce ceramic hollow particles by performing one process coating core material particles with a ceramic powder in a predetermined thickness within a short time by one manufacturing apparatus. CONSTITUTION:In a method for producing ceramic hollow particles, a process coating the surface of spherical core particles 11 with a predetermined particle size composed of an org. material with a ceramic powder 21 through a binder is performed by fluidizing the total amt. of the core particles 11 to spray a predetermined amt. of a binder soln. 31 containing the org. material, an inorg. material or both of them on the core particles 11 and also supplying a predetermined amt. of the ceramic powder 21 to the core particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing hollow ceramic particles used for heat insulating materials, filter materials and the like.

[0002]

2. Description of the Related Art Conventionally, granulated organic core particles are coated with a ceramic powder (including refractory raw material powder; the same applies hereinafter) through a binder, and these are dried, and then the coated ceramic powder is burned. In the production method for producing these sintered hollow body particles by binding, in order to coat the core particles with a ceramic powder to a predetermined thickness, as described in JP-A-2-277544 and the like. Of (a) applies a binder to the core material particles, and then (b) deposits ceramic powder on the binder application surface, and
While repeating the process stepwise, the ceramic powder was coated to a predetermined thickness.

For this reason, in the steps (a) and (b), when the manufacturing apparatuses are separated or when the same manufacturing apparatus is used, different process management is required, resulting in a decrease in yield and an increase in cost. Had the drawback of.

[0004]

DISCLOSURE OF THE INVENTION According to the present invention, a step of coating core particles with a ceramic powder having a predetermined thickness is one step,
The present invention provides a method for producing ceramic hollow body particles which can be performed in a short time with one production apparatus.

[0005]

In order to achieve the above object, the present invention provides a method for producing hollow ceramic particles, which comprises a step of coating the surface of organic core particles with ceramic powder through a binder. The step of coating the spherical organic substance core material particles with ceramic powder to a predetermined thickness is such that a predetermined amount of the core material particles is allowed to flow and a predetermined amount of binder liquid consisting of an organic substance or an inorganic substance or both is sprayed onto the core substance particles. The present invention provides a method for producing ceramic hollow body particles, which comprises supplying a fixed amount of ceramic powder.

In the present invention, the core material particles are composed of spherical particles of an organic combustible substance, and a substance which decomposes at a temperature as low as possible is preferable. Further, when gasifying and passing through the ceramic coating layer, a substance that passes and disappears without destroying the ceramic coating layer is preferable. For this reason, expanded polystyrene sphere particles and polyethylene sphere particles are used. Further, the core material particles preferably have a sphere diameter of about 1 to 10 mm, and have a high roundness and a uniform sphere diameter distribution.

In order to make a predetermined amount of the core material particles flow, a method of putting a predetermined amount of the core material particles in a rotary container as shown in FIG. 1 and rotating the core material particles, as shown in FIG. Examples of the method include a method of suspending 11B after the bottom portion 12B is floated by the pressurized air in the tube 13B, a method of vibrating the container itself after a predetermined amount of the total amount is put into the container, and a method of combining these. In FIG. 2, 2B
Is a hopper containing ceramic powder, and 3B is a binder liquid spray tube.

As the binder liquid, aqueous solutions of various types of cellulose, polyvinyl alcohol, starch, molasses, lignin and the like are used as organic substances, and liquid substances such as water glass, colloidal alumina, colloidal silica and various phosphoric acids are used as inorganic substances. .

Since the jetting of the binder liquid produces fine spray, droplets are usually produced by the nozzle, but centrifugal force due to rotation may be used in some cases.

The ceramic powder usually has a particle size of 0.01-.
The range of 0.84 mm is used, and
The composition includes 70 parts by weight or more of alumina, the balance is mullite mainly composed of silica, 70 parts by weight or more of alumina and the balance is spinel mainly composed of magnesia,
High-silica containing 90 parts by weight or more of silica, alumina 9
High alumina containing 0 parts by weight or more, high magnesia containing 90 parts by weight or more magnesia, high calcia containing 90 parts by weight or more of calcia, both magnesia and calcia 50
Parts by weight dolomite, zirconia containing 90 parts by weight or more of zirconia and those mainly containing oxide ceramics such as silica, alumina, cordierite composed of three components of magnesia, silicon carbide, silicon nitride and sialon In general, the non-oxide ceramics described in 1 above, calcium carbonate, magnesium carbonate, or a mixture containing both of them are used.

The ceramic powder can be supplied by a method such as gravity dropping from a hopper or the like, or a method of ejecting the powder through pressurized air.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention is shown in FIG. 100 parts by weight of expanded polystyrene sphere particles 11 having a diameter of 3 mm are put into the rotary granulator 1. When the rotary granulator 1 is started and the rotational speed is maintained at a predetermined speed, the expanded polystyrene sphere particles 11 that have been introduced form a dish-shaped surface while the height from the bottom is maximized at the side wall due to the centrifugal force. While rotating as a whole, the styrene sphere particles 11 themselves also roll while individually contacting each other. The hopper 2 installed on the upper side of the granulator 1 stores 8000 parts by weight of a ceramic powder 21 of a dried mullite composition whose particle size has been adjusted in advance. Two
1 is charged into the rotary granulator 1 at a predetermined supply rate. At the same time, the binder supply pipe 3 installed in the diameter direction of the granulator 1
1000 parts by weight of the binder liquid 31 (1% aqueous solution of polyvinyl alcohol) is sprayed onto the surface of the rotating particle group 11 from the plurality of nozzles 32 while adjusting the spraying speed in the range of 1 to 5 ml / sec. Styrene ball 1 in 1-3 minutes
The surface 1 is wetted with the binder liquid 31, the ceramic powder 21 is attached, and after about 20 minutes, the surface of the styrene sphere particles is coated with a ceramic layer having a predetermined thickness of 0.5 mm. When the coating of the ceramic layer is completed, the granulated product is taken out from the discharge port on the side wall of the granulator 1 and put in a drying container having a gold net at the bottom. The weight before drying is 9100 parts.

[0013]

According to the manufacturing method of the present invention, in order to coat the core material particles with the ceramic powder of the predetermined thickness, the predetermined amount of the core material particles is made to flow, and then the predetermined amount of the binder liquid is sprayed on it. In addition, by supplying a predetermined amount of ceramic powder, core material particles having a ceramic coating layer of a predetermined thickness can be obtained at once in one step with one manufacturing apparatus, thus omitting process control. It is possible to reduce the cost significantly by improving the yield and improving the yield.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a manufacturing apparatus of the present invention.

FIG. 2 is an explanatory view showing another example of the manufacturing apparatus of the present invention.

[Explanation of sign]

 11 Core Particles 21 Ceramic Powder 31 Binder Liquid

Claims (1)

[Claims] 1. A method for producing hollow ceramic particles, which comprises a step of coating the surface of organic core particles with a ceramic powder via a binder, wherein spherical organic core particles having a predetermined diameter are coated with the ceramic powder to a predetermined thickness. The step is to flow a predetermined amount of the core material particles, and to inject a predetermined amount of a binder liquid composed of an organic material or an inorganic material or both into the core material particles, and to supply a predetermined amount of ceramic powder to the ceramic hollow body particles. Manufacturing method.