Agitating – Rubber or heavy plastic working – Stirrer is through-pass screw conveyor
Patent
1985-05-24
1987-03-24
Simone, Timothy F.
Agitating
Rubber or heavy plastic working
Stirrer is through-pass screw conveyor
366 90, 366322, 366323, B29B 110
Patent
active
046521380
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a single screw kneading extruder for performing both a kneading action and a blending action.
BACKGROUND ART
Published Unexamined Japanese Patent Application No. SHO 57-87344 is known and proposes an extrusion mixer comprising a rotor and a stator which are formed with semispherical cavities. The extrusion mixer (hereinafter referred to as "CTM") is so adapted that a fluid, while passing over the cavities, is subjected to a uniform blending action by being cut and sheared owing to the movement of the fluid from cavity to cavity and to the rotation of the rotor. Accordingly, the mixer exhibits remarkable blending and dispersing ability, for example, when preparing a compound from molten polyethylene and a carbon master batch composed similarly of polyethylene and carbon black dispersed therein in high concentration by uniformly blending the master batch with the melt, or when preparing a polymer blend from at least two kinds of molten polymers, which are different in flowability, by uniformly blending the melts together.
With the CTM, however, it is extremely difficult to obtain a homogeneous dispersion by blending a filler, such as carbon black or calcium carbonate, directly with polyolefin, because carbon black, calcium carbonate or like powder flows into the cavities before being fully kneaded into the polymer, filling up the cavities and rendering the machine inoperative for blending action. Further in order to knead agglomerates of particles into the polymer to obtain a uniform dispersion, the agglomerates must be broken down by shearing forces, but the shearing force acting on the fluid within the CTM is small and insufficient to break down the agglomerates of particles.
When mixing particles with a polymer to obtain a blend which is uniform on a microscale, the materials needs to be crushed or mashed by a shearing force, suitably with use of a mixer or kneader having such crushing or mashing action. It is well known that machines, such as Banbury mixers, in which the charge is crushed in a wedge-shaped space, are suitable for this purpose.
SUMMARY OF THE INVENTION
In view of the above, the present invention provides a single screw kneading extruder which, although a single machine, is adapted to perform the outstanding blending action of the CTM and the action to be typically afforded by a Banbury mixer to knead powdery additives of the like by a powerful shearing force.
The present invention provides a single screw kneading extruder having a kneading portion comprising a rotor and a stator surrounding the rotor, the kneading extruder being characterized in that it comprises a first-stage kneading portion having a rotor provided with kneading blades, a second-stage kneading portion aligned with the first-stage kneading portion and having a rotor and a stator each formed with cavities, and a feed portion interconnecting the two kneading portions for feeding a blend from the first-stage kneading portion to the second-stage kneading portion. Accordingly, the first-stage kneading portion affords an outstanding kneading action with the kneading blades which are tipped, while the second-stage kneading portion provides an outstanding blending action by the cavities formed in its rotor and stator, thus enabling the extruder to act efficiently for kneading and blending although it is a single machine.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 is a sectional view schematically showing an embodiment of the present invention;
FIG. 2 is a view in section taken along the line A--A in FIG. 1;
FIG. 3 is a view in section taken along the line B--B in FIG. 1;
FIG. 4 is a diagram showing an arrangement of cavities; and
FIG. 5 and FIG. 6 are sectional views schematically showing other embodim
REFERENCES:
patent: 2607077 (1952-08-01), Dulmage
patent: 3788614 (1974-01-01), Gregory
patent: 3825236 (1974-07-01), Hussmann et al.
patent: 3957256 (1976-05-01), Murakami
patent: 4074362 (1978-02-01), Kruder et al.
patent: 4154536 (1979-05-01), Sokolow
patent: 4514163 (1985-04-01), Nakamura
Fukumizu Shin'ichi
Fusamoto Akiro
Inoue Kimio
Kabushiki Kaisha Kobe Seiko Sho
Simone Timothy F.
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