Coating processes – Particles – flakes – or granules coated or encapsulated
Reexamination Certificate
1997-03-06
2001-02-27
Beck, Shrive (Department: 1762)
Coating processes
Particles, flakes, or granules coated or encapsulated
C427S215000, C427S248100
Reexamination Certificate
active
06194028
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method of improving a particle surface by forming a film thereon to improve the property of a particle.
BACKGROUND OF THE INVENTION
Covering the surface of a microscopic particle with a surface improving agent has been known as a technique to improve the particle surface. This technique is applied to either dry particles or particles in a liquid-phase. More specifically, this technique includes a kneading method, a stirring method using a medium, a spray dry method for coating a particle surface with a surface improving agent. These methods are well known and the detailed description is set forth in the following:
1. “Microscopic Particle Engineering: Basic and Application of Dispersion”, pp. 123-136, edited by Japan Powder Industrial Technical Association and published by Asakura Shoten K. K.; and
2. “Today's Chemical Engineering 45 Microscopic Particle Engineering”, edited by Chemical Engineering Association and published by Chemical Industrial Co., Ltd.
However, the above conventional particle surface improving methods have following problems:
(1) the particles are charged during the surface improving treatment, and the resulting charged particles are difficult to handle in the following procedure;
(2) the surface improving treatment takes quite a long time; and
(3) the surface improving treatment demands a complex manipulation and the actual operation depends on an expensive apparatus for the most part.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an apparatus and method of improving a particle surface which can improve the particle surface more readily in a shorter time than conventional methods without charging the particles.
To fulfill the above object, a method of improving a particle surface of the present invention is characterized by having the step of:
exposing particles to a supersaturation atmosphere of a surface improving agent that improves a property of a particle surface, so that a film of the surface improving agent is formed on the particle surface by letting the surface improving agent condense thereon.
The above arrangement makes it possible to form a film of the surface improving agent, namely, a surface improving film, on the particle surface without any action such that charges the particles, for example, stirring the particles.
Thus, the particles are not charged during the surface improving treatment, and the resulting surface improved particles are easy to handle.
Also, compared with an operation like stirring, it takes a very short time to form the surface improving film on the particle surface by exposing the particles to the supersaturation atmosphere of the surface improving agent to let the surface improving agent condense on the particle surface.
In addition, the present particle surface improving method uses a simple physical phenomenon that the supersaturation atmosphere of the surface improving agent is produced and the particles are exposed to the same to let the surface improving agent condense on the particle surface. Thus, the present particle surface improving method can be manipulated easily and carried out by a simple and inexpensive apparatus.
Further, the surface improving film grows on the particle surface to have a constant thickness due to its own surface tension, thereby making it possible to coat the particles with the surface improving film of a uniform thickness.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.
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Akazawa Yoshiaki
Horiuchi Takahiro
Izumi Hideshi
Kubota Hiroshi
Morinishi Yasuharu
Beck Shrive
Chen Bret
Conlin David G.
Dike Bronstein, Roberts & Cushman LLP
Neuner Geroge W.
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