Mixing apparatus and method
AssigneeExxon Research & Engineering Co.
InventorsDonald G. Stenmark, Raymond L. Heinrich
Life of this patent
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Abstract
A single screw extruder, comprising a rotatable core means in an extruder barrel, is provided with spaced-apart discontinuous helical flights arranged on the rotatable core means with each flight centered in the channel formed by the preceding flights, the flights being formed by lands on the core means, and each land having a traversed axial length of about one diameter unit of the core means. The extruder is particularly useful in filler compounding of solid polyolefins, the blending of different polyolefins, and the reacting of monomers with polyolefins such as in extruder grafting.
Claims9
A method of mixing a polyolefin and an additive which comprises introducing them into a single screw extruder having a rotatable core means comprising in combination:
- a. an extruder screw means having a succession of individual spaced apart, offset, discontinuous, helical flights disposed on said screw means to form channels between said flights;
- b. each successive flight being centered in a channel of preceding flights;
- c. said flights having the narrowest-width-channel within the range from about -0.25 to about three diameters of said core means, the diameter of said core means including said flights;
- whereby said polyolefin and said additive form a flowing first stream within said extruder, having a helical and longitudinal motion relative to the helical axis of the first stream, said first stream is subsequently split into at least second, third, fourth and fifth flowing streams, said second and third streams being subsequently combined with said fourth and fifth streams, successively repeating the said forming, splitting and combining steps to generate a number of mixed streams which increases exponentially with the length of said longitudinal motion, and recovering mixed polyolefin and additive from said extruder.
A method of mixing two or more ingredients which comprises the steps of:
- 1. introducing said ingredients into a single screw extruder having a rotatable core means comprising in combination:
- a. an extruder screw means having a succession of individual spaced apart, offset, discontinuous, helical flights disposed on said screw means to form channels between said flights;
- b. each successive flight being centered in a channel of preceding flights;
- c. said flights having the narrowest-width-channel within the range from about -0.25 to about three diameters of said core means, the diameter of said core means including said flights;
- 2. forming a material within a confined zone into a flowing first stream having a helical and longitudinal motion relative to the helical axis of the first stream;
- said motion being imparted by rotation of at least a portion of said zone;
- 3. splitting said flowing first stream within said confined zone into at least second and third flowing streams having the same motion as the first stream;
- 4. combining said second and third streams, respectively, with at least fourth and fifth streams formed in the same manner and having the same motion as said second and third streams;
- 5. successively repeating said preceding steps to generate a number of mixed streams which increases exponentially with the length of said longitudinal motion;
- and
- 6. recovering mixed material from said confined zone.
Dependencies are inferred from the claim text.