Agitating – By injecting gas into mixing chamber – With stirrer
Patent
1990-07-19
1991-10-15
Hornsby, Harvey C.
Agitating
By injecting gas into mixing chamber
With stirrer
366314, 366343, B01F 720
Patent
active
050569260
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the treatment of a particulate thermoplastic material with a purging gas.
A "thermoplastic material" is intended to mean any organic polymer or copolymer which is solid at room temperature and capable of being made relatively fluid by heating to a temperature above room temperature. As a thermoplastic material which can be chosen according to the invention there may be mentioned polystyrenes, polyethylenes, polypropylenes and so-called ABS resins.
A "particulate thermoplastic material" is intended to mean a thermoplastic material in the divided state, which is in the form of particles, for example of grains, granules or pearls, which have any individual shape, for example spherical, cubical, and the like. A powder of a thermoplastic material or a pulverulent thermoplastic material corresponding [sic]especially to this definition.
The present invention is now described, defined and discussed with reference to the use of the process of coloring by coating according to Patent Application FR-A-2,317,069; the content of the latter is incorporated into the present description as far as need be. It should be understood, however, that an apparatus according to the invention can accommodate many applications other than coloring by coating, as indicated hereinafter.
According to the abovementioned patent application, a process of coloring by coating has been described, consisting generally in:
agitating a charge of particulate thermoplastic material;
mixing with this charge a coloring liquid comprising an inert solvent, a colorant in suspension or solution in the said solvent, and a binder dissolved in the said solvent;
evaporating the solvent by circulating a purging gas stream through the charge, during or after the agitation of the latter; whereby particles of thermoplastic material are obtained, which are coated with a surface coating of the binder in which the colorant is uniformly dispersed.
A suitable apparatus for making use of the abovementioned process has been described and proposed in Patent Application FR-A-2,317,069. This apparatus comprised:
A) a stationary container for receiving a charge of the particulate thermoplastic material, whose side wall has a shape of revolution, for example cylindrical, relative to a vertical axis; this container is equipped with a means for introducing the charge to be colored, namely an articulated cover, with a means for discharging the colored charge, for example a spout situated at the bottom of the container, and with a means for circulating the purging gas stream through the container; the latter means comprises, on the one hand, a means for introducing air (or another gas) within the agitating rotor described below and, on the other hand, a means for removing by suction the gas stream which is introduced, arranged on the cover.
B) a rotor for agitating the charge, movable in rotation relative to the container and around the vertical axis, and arranged essentially inside the said container; this rotor comprises:
a hollow axial shaft for introducing the purging air and provided with a means for driving in rotation; this hollow shaft passes through the bottom of the container and the means for driving in rotation is situated outside the latter;
three hollow blades for upward centripetal flow, whose interior communicates with that of the axial shaft; each blade comprises, on the one hand, a radial arm extending radially and horizontally from the axial shaft, in the lower part of the container, and, on the other hand, a vertical upright extending axially and vertically inside the container; each blade is provided, on the one hand, with a front face, namely a face sloping forward in the case of the radial arm, and a face which is oblique toward the center of the receptacle in the case of the vertical upright, respectively, and, on the other hand, a perforated back face for injecting the purging air.
The utilization of an apparatus such as that described above for making use of the coloring process defined above has disclosed the following
REFERENCES:
patent: 1536203 (1925-05-01), Frydenlund
patent: 3884135 (1975-05-01), Lohr
patent: 4070957 (1978-01-01), Kovekawa
patent: 4201482 (1980-05-01), Imhauser
Bouheben Christophe
Bouheben Guy
Giambrone Carole
Hornsby Harvey C.
Till Terrence R.
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