JPS63319037A - Method and device for modifying surface of powder - Google Patents

Abstract

PURPOSE:To make the bonding of base particles and secondary particles sure by dispersing and spraying the composites in which the surfaces of the base particles becoming nucleuses are covered with the fine particulate secondary particles by means of frictional electrification into hot air and instantaneously melting the surface layer parts and cooling them. CONSTITUTION:Composites A are formed by sticking secondary particles (b) on the surfaces of base particles (a) becoming nucleuses by means of frictional electrification. The composites A are fed to a proportioning feeder 1 and fed to a vibrating feeder 3 via a discharge port 2 at quantitative amount and thereafter fed to a spraying nozzle 4. The composites A discharged through the tip of the spraying nozzle 4 are jetted toward the inside of the hot-air current jetted through a hot-air nozzle 7. The composites A are passed through the hot-air current and thereby all particles are heated at high temp. homogeneously and instantaneously in a dispersion state and therefore the composites formed by frictional electrification are completely fixed and encapsulated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for surface modification of powder and an apparatus therefor.

[Conventional technology and its problems]

The purpose is to manufacture functional particles for electronic toner, pharmaceuticals, cosmetics, biochemicals, electronic materials, etc., or to improve the fluidity, dispersibility, wettability, color tone, particle size distribution, electromagnetic properties, taste, etc. of various powders. For the purpose of improving physical properties, it has been common practice to form a composite by coating the surface of a core mother particle with fine child particles and then subjecting it to immobilization treatment or film formation treatment.

FIG. 3 shows an example of a conventional apparatus for immobilizing or forming a film on the above-mentioned composite.

This device is equipped with a hot air supply cylinder 21 at the upper part of the outer periphery of the tower 20, blows hot air into the inside of the tower 20 from the supply cylinder 21 and swirls it, and supplies the inside of the tower 20 from a raw material supply port 22 formed at the upper part of the tower 20. Composite A is supplied and brought into contact with hot air.

By the way, in the above device, the hot air blown from the supply cylinder 21 is swirled inside the tower 20, so the temperature of the tower 20 becomes high, and the composite A moves along the inner diameter surface that has become high temperature. When the composite A is melted, the composite often adheres or becomes fixed to the inner diameter surface of the tower 20. For this reason, the fluidity of the composite is poor, and the temperature of the hot air cannot be increased, resulting in the disadvantage that processing takes a long time.

Furthermore, since the temperature cannot be raised, the composite cannot be made into a spherical shape, and the child particles cannot be reliably attached to the mother particles.

[Objective of the Invention] Therefore, the present invention solves the above-mentioned inconvenience and efficiently produces a composite consisting of a mother particle and child particles triboelectrically charged.
Another object of the present invention is to provide a method for surface modification of powder and an apparatus therefor, which enable reliable fixing treatment or film formation treatment.

[Structure of the Invention] In order to achieve the above object, the first invention is to disperse and inject into hot air a composite body in which fine child particles are coated on the surface of a core mother particle by triboelectric charging, to form child particles. At least one of the surface layer of the base particle and the surface layer of the base particle were melted instantly and then cooled.

In addition, the second invention disperses and injects, around a hot air injection nozzle, into the hot air injected from the nozzle, a composite in which the surface of a mother particle serving as a core is coated with fine child particles by frictional charging. A composite collection hood with a composite injection nozzle arranged therein and facing the hot air injection nozzle;
The structure was such that it was connected to the collector through a suction pipe that served as an outside air intake for cooling.

[Embodiments] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1(a) shows complex A. This composite A consists of a mother particle a serving as a core and fine child particles S coated on the surface of the mother particle A, and the child particles A are attached to the mother particle A by frictional electrification. Here, at least one of the mother particle a and the child particle S may be made of a polymeric material, and the other may be amorphous.

The composite A is supplied to a quantitative feeder 1, and is quantitatively supplied from a discharge port 2 of the feeder 1 to a vibrating feeder 3 located below.

A composite injection nozzle 4 is arranged below the vibratory feeder 3, and a lower outlet of a hopper 5 is connected to the injection nozzle 4. The hopper 5 is located below the tip of the vibrating feeder 3, and the composite A supplied from the vibrating feeder 3 into the hopper 5 is drawn into the injecting nozzle 4 by the ejector action of the compressed air flowing in the injecting nozzle 4. and is injected at low pressure from the tip of the nozzle 4.

A hot air generator 6 is provided around the composite injection nozzle 4, and the hot air generated by the hot air generator 6 is
It is injected upward from the upper injection nozzle 7.

The composite A discharged from the tip of the composite injection nozzle 4
is injected into the hot air stream injected from the hot air injection nozzle 7.

In this case, the composite injection nozzle 4 is provided with a required inclination angle so that the jet stream from the composite injection nozzle 4 does not cross the hot air flow. Also, the composite injection nozzle 4
To avoid a rise in temperature, place the lamp in a location where it will not shine directly into the hot air current.

The temperature of the hot air injected from the hot air injection nozzle 7 is appropriately determined depending on the materials of the mother particle a and the child particles forming the composite A, so that at least one of the surface layer of the mother particle a and the child particle The temperature should be such that it melts instantly.

Note that it is preferable that the diameter of the hot air outlet of the hot air injection nozzle 7 is adjustable so that the degree of rise in the hot air can be adjusted.

By injecting the composite A into the hot air stream as described above, the composite A is instantaneously heated to a high temperature in a homogeneous manner with all particles in a dispersed state by interrupting the hot air stream. Therefore, the triboelectrically charged composite A is completely immobilized and encapsulated as shown in FIG. 1 ((2)).

In this case, if the softening temperature of the base particle a is lower than the softening temperature of the child particle S, the surface layer of the base particle a will melt and become spherical,
The child particles adhere to the surface of the mother particle a, and in the opposite case, the child particles melt and become spherical, forming a film on the surface of the mother particle a.

The encapsulated composite A' is collected in a hood 8 facing the hot air injection nozzle 7. The hood 8 and a collector 9 such as a cyclone are connected by a suction pipe 10, and a damper 11 for taking in outside air is connected to the end of the suction pipe.

Further, a collector mja 12 equipped with a suction blower is connected to the exhaust port of the collector 9, and suction force is applied to the suction pipe 10 when the suction blower operates.

Therefore, the composite A' collected in the hood 8 flows through the suction pipe 10 and is collected in the collector 9. In this case, since outside air is taken into the suction pipe 10 from the damper 11, the complex A' is cooled and the suction pipe 10
It flows smoothly into the collector 9 without adhering or sticking to the inner surface of the container.

Note that by providing a cooling jacket 13 on the outside of the suction pipe 10 and cooling the suction pipe 10 by supplying cold water to the cooling jacket 13, the composite body A' can be cooled more effectively.

[Effects] As described above, the present invention disperses and injects the composite into the hot air jetted from the hot air jetting nozzle, so that the surface of the composite can be heated evenly and instantly to a high temperature. Since at least one of the mother particles and the child particles is melted by heating, the mother particles and the child particles can be reliably fixed and encapsulated.

In addition, since the melted part due to heating becomes rounded and spherical, a spherical product with less unevenness can be obtained.

Furthermore, the composites encapsulated or spheroidized by heating are collected in a hood and introduced into a suction pipe that sucks in outside air, so that the composites can be cooled during transportation. Therefore, the complex does not adhere to the inner surface of the suction pipe or the collector, and as a result, continuous operation is possible.
Almost 100% can be recovered as a product, and
Since the collector is open to the atmosphere, there is no risk of dust explosion and is extremely safe.

In addition, there are no moving parts such as rotating bodies, and the structure of the device is simple, so maintenance is easy.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional view of a composite consisting of a mother particle and child particles, FIG. 1(b) is a cross-sectional view of the same composite in an encapsulated state, and FIG. Flow diagram, 3rd
The figure is a schematic diagram of a conventional powder reforming device. 4...Composite injection nozzle, 7...Hot air injection nozzle, 8...Hood, 9...Collector, 10... suction pipe.

Claims (2)

[Claims] (1) A composite in which the surface of a core mother particle is coated with fine child particles by triboelectric charging is dispersed and sprayed into hot air to instantaneously melt at least one of the child particles and the surface layer of the mother particle, and then cooled. A method for surface modification of powder, characterized by: (2) A composite injection nozzle is installed around the hot air injection nozzle that disperses and injects a composite in which the surface of a core mother particle is coated with fine child particles by frictional charging into the hot air injected from the nozzle. A powder surface modification device in which a composite collection hood and a collector facing the hot air injection nozzle are connected by a suction pipe having an outside air intake for cooling.