JPH03154630A - Manufacture of hollow particle - Google Patents

Abstract

PURPOSE:To manufacture hollow particles with the dust production reduced by an injection molding or the like by a method wherein inorg. or org. powders are heated and mixed together in a granulating machine, powder-like core materials are added therein to heat the powders for granulation into the particles and such particles are cooled, or baked and cooled. CONSTITUTION:Inorg. or org. powders are mixed while being heated in a granulating machine such as Eilich mixer-equipped mixing granulator and drum type mixer-equipped rolling granulator. The powder-like core materials consisting of a heat-meltable substance are then added into the granulating machine, the granulation is continuded while heat is being applied and the particles thus formed are thereafter cooled or cooled following baking to manufacture hollow particles. By way of example, the powder-like core materials consisting of the heat-meltable substance may be wax, plasticizer, rubber and resin, preferably with the size of at most about 0.5mm in diameter. The inorg. or org. powder having the size of 0.01-100mu in diameter is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing hollow particles useful as lightweight aggregates and lightweight plastic reinforcements.

[Conventional technology/section! ! ! ] Hollow particles (balloons) have traditionally been used to reduce the weight of composite materials such as synthetic wood, various building materials, buoys, marine materials, and vehicle materials.

The following are known hollow particles used for the above-mentioned purposes: 0Glass (silica) balloons made by blowing up microscopic glass spheres to which a blowing agent has been added; ■Glass (silica) balloons made in coal-fired power furnaces, blast furnaces, etc. Fly ash balloons; ■Shirasu balloons made by inflating volcanic ash; Organic balloons made from phenol, urea, styrene, saran, etc., made by inflating resin powder added with zero blowing agents.

In addition, inorganic powders such as carbon black and xonotlite, and organic powders such as wood flour and coconut flour have traditionally been used as fillers for resins, but these powders cause environmental pollution due to scattering during handling. There were problems such as the occurrence of a bridging phenomenon in the hopper of an injection molding machine or an extrusion molding machine.

Further, in order to reduce the weight of composite materials, etc., no technology has been developed for producing hollow particles from these inorganic powders and organic powders by a simple method.

Therefore, an object of the present invention is to provide a method for granulating inorganic powder or organic powder into hollow particles by a simple method that can eliminate the above-mentioned drawbacks.

[Means for Solving the Problems] That is, the present invention mixes an inorganic powder or an organic powder while heating it in a granulator, and then produces a powdery core material made of a substance that becomes liquid when heated. It relates to a method for producing hollow particles, which is characterized in that the particles are added to a granulator and granulated while being continuously heated, and then cooled or fired, and then cooled.

[Function] Powders that can be granulated into hollow particles by the method of the present invention are not particularly limited, and include inorganic powders, organic powders, and composite materials that may cause environmental pollution such as dust generation during use. The target is powder that is useful for reducing the weight of.

Inorganic powders to which the method of the present invention can be applied include carbon, chromium oxide, zinc white, ferrite, titanium dioxide, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, mica powder, bentonite, talc, clay, silica, Examples include calcium carbonate, magnesium carbonate, and sodium bicarbonate.

In addition, organic powders to which the method of the present invention can be applied include wood flour, coconut flour, rice husk powder, polyamide resin powder, phenolic resin powder, fluororesin powder, polyacetal resin powder, polysulfide resin powder, polyimide resin powder, unsaturated resin powder, Examples include polyester resin powder.

The inorganic powder or organic powder used in the present invention has a particle size of 0.
．． It is within the range of 0.01 to 100 μm, preferably 0.1 to 20 μm. Inorganic powder or organic powder having such a particle size is placed in a granulator and mixed while heating.

Granulators that can be used in the process of the invention are, for example, mixed granulators or transfer granulators. Examples of the mixing granulator include an Eirich mixer, a Henschel mixer, and a Loedige mixer. Examples of the transfer granulator include a pan-type mixer and a drum-type mixer.

The heating temperature of inorganic powder or organic powder in a granulator varies depending on the material of the powder core material, which is made of a substance that becomes liquid upon heating, which will be described later, i.e., the melting point, etc., and is not particularly limited. Although it is not necessary, it is important to heat the powder to a temperature at which it gradually melts when it is added. This is because if the core material is heated to such a temperature that it melts immediately, the hollow particles of the present invention cannot be formed because they are formed by the process described below.

Next, once the inorganic powder or organic powder has been uniformly heated to a predetermined temperature, the JJUv! Then, a powdery core material made of a substance that becomes liquid is added. When this powdery core material is added, first, inorganic powder or organic powder adheres around the core material to form an inorganic powder layer or an organic powder layer,
Next, the core material is gradually melted by heating and diffused into the inorganic powder layer or organic powder layer, and the molten core material becomes a binder and gradually forms the inorganic powder layer or organic powder layer. When the core material becomes thick and all of the core material melts, the core material disappears and becomes a hollow particle.

The obtained hollow particles can be cooled as is or after being fired. Note that this cooling operation and firing operation are not particularly limited.

The powder core material made of a substance that becomes liquid when heated is used in the present invention, for example, wax, plasticizer, metal soap, rubber,
They can be resins, lubricants, saccharides, oils, and mixtures thereof, and any particle size can be used depending on the particle size of the hollow particles obtained, but 0.5 mm or less, especially 0.5 mm or less, It is preferable to use particles with a particle size of .1 mm or less.

Further, the mixing ratio of the inorganic powder or organic powder and the powdery core material is preferably about 5/1 to 1/2.

The reason for this is that if the powdery core material is small, the inorganic powder or organic powder will not completely form hollow particles, and if the powdery core material is large, the powdery core material will remain inside the hollow particles.

[Example] Example 1 500 g of carbon black with an average particle size of 0.05 μm was placed in a mixing granulator (Eirich mixer), mixed while heating to 115°C, and then carbon black with an average particle size of 0.5 mm was added. 200 g of wax (paraffin wax, melting point 50 DEG C.) was added and granulated for 30 minutes at an agitator rotation speed of 2500 rpm, and then cooled to obtain hollow particles having a particle size of 3III11 or less and a bulk specific gravity of 0.3.

The obtained hollow particles generated little dust, did not cause bridging in the hopper of an injection molding machine, and were effective.

Example 2 500 y of xonotlite powder with an average particle size of 70 μm was placed in a mixing granulation 81 (Eirich mixer) and mixed while heating to 115° C. Next, wax (paraffin wax, melting point 50 ℃) 200y and granulated for 30 minutes at an agitator rotation speed of 2500 rpTQ to obtain hollow particles with a particle size of 4III11 or less, and then:
Hollow particles having a bulk specific gravity of 0.2 were obtained by firing at 900° C. for 30 minutes in a firing furnace.

After mixing the obtained hollow particles with liquid phenolic resin,
When molded, a lightweight resin molded article could be obtained.

[Effects of the invention] The hollow particles obtained by the method of the present invention generate less dust when used in hoppers of injection molding machines, extrusion molding machines, etc., can prevent bridging phenomena, etc. Since the resulting granulated particles are hollow particles and have a high bulk specific gravity, they are effective as lightweight reinforcing materials and lightweight aggregates for resin moldings.

Claims (1)

[Claims] Inorganic powder or organic powder is mixed while being heated in a granulator, and then a powdery core material made of a substance that becomes liquid when heated is added to the granulator and granulated while continuing to heat. , cooling or sintering, and then cooling.