Patent Abstract:
A batch mixer is equipped with a plunger for pushing material from the batch mixer. The batch mixer includes a mixer tank structured to accommodate material. The mixer further includes a mixer head comprising at least one blade structured to blend the material within the mixer tank. The mixer further includes a plunger mechanism structured to push the blended material directly from the mixer tank.

Full Description:
FIELD OF THE INVENTION 
     The invention relates to a batch mixer and, more particularly, to a batch mixer equipped with a plunger for pushing material from the batch mixer. 
     BACKGROUND OF THE INVENTION 
     Several techniques are available to process polymers, including twin screw extruders and batch mixers. Batch mixers provide for increased residence time of polymeric materials, which improves shearing history of the polymeric materials. 
     Batch mixers, such as a Banbury® mixer, are known in the art of mixing polymeric materials. These batch mixers have several shortcomings, however. For example, in known batch mixers, after blending or mixing of the material is complete, the mixers are opened and the polymeric materials are manually scooped out from the mixer. This is done with the material in a molten state. This process is time consuming, expensive and complicated. When the polymeric material is solidified as a molten chunk, the polymeric material may be put in a crusher to form polymer granules. However, this form of materials cannot be pelletized. 
     Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the invention, a batch mixer comprises a mixer tank structured to accommodate material. The mixer further comprises a mixer head comprising at least one blade structured to blend the material within the mixer tank. The mixer further comprises a plunger mechanism structured to push the blended material directly from the mixer tank. 
     In another aspect of the invention, a batch mixer comprises a mixer tank having an interior portion structured to accommodate polymeric material. The mixer further comprises a mixer structured to blend the polymeric material within the interior portion of the mixer tank. The mixer is rotatable and moveable in a vertical direction along a shaft. The mixer further comprises a plunger mechanism structured to push the blended polymeric material through a die in fluid communication with the interior portion of the mixer tank. The plunger mechanism is rotatable and moveable in the vertical direction along the shaft. The mixer further comprises a plurality of limiters structured to limit the vertical movement of the plunger mechanism and the mixer. 
     In yet another aspect of the invention, a method of mixing material comprises: placing material within a tank; placing a mixing head on the tank, and mixing the material within the tank with the mixing head; removing the mixing head from the tank; placing a plunger mechanism on the tank; moving the plunger mechanism within the tank to push the mixed material from a die; and removing the plunger mechanism from the tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention. 
         FIG. 1  shows a batch mixer according to aspects of the present invention; 
         FIG. 2  shows the batch mixer with a mixer head on a mixer tank according to aspects of the present invention; 
         FIG. 3  shows the batch mixer with a plunger head on the mixer tank according to aspects of the present invention; 
         FIG. 4  shows material being pushed from the batch mixer according to aspects of the present invention; and 
         FIG. 5  shows material being formed into pellets according to aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention relates to a batch mixer and, more particularly, to a batch mixer equipped with a plunger for pushing material from the batch mixer. More specifically, in embodiments, the batch mixer includes a plunger mechanism to push material through a die of a mixer tank. Advantageously, the present invention provides for semi-continuous operation while controlling the residence time of a mixing and compounding process of, e.g., polymeric materials. Accordingly, polymeric materials may be easily and efficiently discharged from the batch mixer and fabricated into desired pellet shapes. As such, the present invention provides for a more cost-effective removal of polymeric materials from the batch mixer. 
     In the area of polymer processing, mixing and blending, whether in solution or molten form, of different polymers with each other and blending them with organic and/or inorganic fillers and additives is important. The quality of mixing, blending, and compounding of polymeric materials, e.g., plastics, determines the properties of the final product. The benefit of using batch mixers over conventional systems, e.g., twin screw extruders, is that the residence time is higher in batch mixers such that shearing history of the polymeric material is considerably improved. 
     Advantageously, the batch mixer of the present invention is capable of pushing material, e.g., polymeric material or food products, from the batch mixer, using a plunger mechanism. This avoids the shortcomings of known mixers, which require the user to open the mixer and manually scoop out the material, e.g., polymeric material, from the mixer, in a molten state (which is a time consuming and costly process). Thus, compared to conventional systems, in the batch mixer of the present invention, processed material, e.g., polymeric material or food products, may be easily and efficiently drawn out of the mixer and fabricated to a desired shape using a plunger and die system. Also, advantageously, the material exiting from the die may automatically be guided through a water bath to a pellitizer to obtain material in pellet form. The batch mixer is also equipped with an opening to introduce inert or purging gas into the batch mixer and/or to suck air out of the batch mixer, thus allowing the batch mixer to operate under vacuum. 
     In embodiments, the material may be related to the research and development of food products. Many food products undergo a mixing process in order to achieve characteristics such as texture, homogeneity, composition and temperature. In embodiments, food mixing can include nano-emulsions, large particle suspensions, highly viscous pastes, or dry powders, with or without the incorporation of gas. In embodiments, the mixing may be: solid-solid mixing, such as powders or textural effects; liquid-solid mixing, such as butters, pastes and dough; liquid-liquid mixing, such as emulsions, margarines, and spreads; or gas-liquid mixing, such as fermentation or chlorination. Accordingly, mixing and blending of food products with additives, flavorings, texture, and other fillers is provided herein. In embodiments, the production of food pellets and flakes such as cereals, pastas, and candies require longer mixing times. As such, the present invention may be of great help to food research and development and food product mixing. 
       FIG. 1  shows a batch mixer according to aspects of the present invention. More specifically,  FIG. 1  shows a batch mixer  1  having mixer tank  5  supported on support bases  15   a ,  15   b  by support bars  10   a ,  10   b , respectively. It should be understood by those of skill in the art that any number of support bars and support bases are contemplated by the present invention. In embodiments, the mixer tank  5  has a diameter of about 10 cm and a height of about 20 cm; although other dimensions are contemplated by the present invention. The mixer tank  5  includes an interior portion that accommodates material, e.g., mixing, blending, and compounding, whether in solution or molten form, different polymers with each other and blending them with organic and/or inorganic fillers and additives. 
     The mixer tank  5  also includes a die  20  in fluid communication with the interior portion. The die  20  is structured to discharge materials from the interior portion of the mixer tank  5 , as discussed below. A valve  22  is provided for controlling the flow rate of the material being discharged through the die  20 . In embodiments, the die  20  can be customized to any desired shape such as a slit, annular, etc. 
     In embodiments, the mixer tank  5  further includes an opening  25  (e.g., pipe in fluid communication with an interior of the mixer tank) which can be used to introduce an inert or purging gas into the mixer tank  5  to prevent undesired chemical reactions from taking place within the mixer tank  5 . In alternate embodiments, the opening  25  is used to remove air or other gases from the mixer tank  5 , thus creating a vacuum. 
     As further shown in  FIG. 1 , the batch mixer  1  includes a mixer head  29 . The mixer head  29  includes a cover  30 , and one or more mixer blades  35  which are operable by a high-torque motor  45 . In embodiments, the high-torque motor  45  is connected to the one or more mixer blades  35  by a shaft  40 , in order to rotate the one or more mixer blades  35 . In this way, the high-torque motor  45  drives the shaft  40  thereby causing the one or more mixer blades  35  to mix and blend the materials, e.g., molten polymer blends and compounds or food products, within the mixer tank  5 . The one or more mixer blades  35  may be of different shapes and designs to ensure well mixed and/or blended materials. For example, the one or more mixer blades  35  can be paddle blades. In embodiments, the mixer blades  35  can also be gyrated in a rotational or partial rotational manner, as well as configurations which act as a vertical chopping. 
     Still referring to  FIG. 1 , the batch mixer  1  further includes a plunger head  49 . The plunger head  49  includes a plunger  50  attached to a screw driven shaft  55 . In embodiments, the screw driven shaft  55  is connected to a motor  60  in order to lower and raise the plunger  50 , when in the mixer tank  5 . In this way, in operation, the plunger  50  can discharge materials from the mixer tank  5 , through the die  20 . The plunger  50  is preferably made of stiff and thermal stable materials capable of withstanding temperatures up to about 300° C., while being able to push molten materials through the die  20 . 
     In embodiments, the mixer head  29  and plunger head  49  are rotatably attached to a shaft  65  using an arm  70   a  and an arm  70   b , respectively. Specifically, the mixer head  29  is connected to (mounted to) and spaced from the shaft  65  by the arm  70   a  extending between the shaft  65  and the mixer head  29 , and the plunger head  49  is connected to (mounted to) and spaced from the shaft  65  by the arm  70   b  extending between the shaft  65  and the plunger head  49 . In embodiments, the arms  70   a ,  70   b  are rotated manually; however, in alternate embodiments, the arms  70   a ,  70   b  can be rotated automatically using a motor  75 . In further embodiments, the mixer head  29  and plunger head  49  move vertically along the shaft  65 . Specifically, both the mixer head  29  and the plunger head  49  are rotatably mounted to the shaft  65  and moveable relative to the shaft and along a length of the shaft. Similar to the rotational movement of the arms  70   a ,  70   b , in embodiments, the vertical movement of the arms  70   a ,  70   b  may be performed either manually or automatically. The vertical movement of the arms  70   a ,  70   b  is limited by the pins  75   a - 75   c  (e.g., mechanical structures or limiters). The pins  75   a - 75   c  can also lock the arms  70   a ,  70   b  to the shaft  65  at certain operational positions. In alternate embodiments, other pins or other locking mechanisms are contemplated by the present invention. 
     More specifically, the pins  75   a  and  75   b  limit the movement of the mixer head  29 , in the vertical direction; whereas, the pins  75   b  and  75   c  limit the movement of the plunger head  49 , in the vertical direction. In embodiments, the pins  75   a - 75   c  can also lock the mixer head  29  and plunger head  49  at certain operational positions along the shaft  65 . In particular, the pin  75   a  can lock the mixer head  29  in the raised position, and the pin  75   b  can lock the mixer head  29  in a lower position (i.e., when the mixer head  29  is sealed to the mixer tank  5 ). Similarly, the pin  75   c  can lock the plunger head  49  in the lower position, and the pin  75   b  can lock the plunger head  49  in a raised position (i.e., when the plunger head  49  is sealed to the mixer tank  5 ). As one of skill in the art should recognize, in embodiments, the plunger head  49  is located in the raised position (sealed to the mixer tank  5 ), while the mixer head  29  is in the raised position (remote from the mixer tank); whereas the mixer head  29  is in the lowered position (sealed to the mixer tank  5 ), while the plunger head  49  is in the lowered position (remote from the mixer tank). It should be understood by those of skill in the art, that the plunger head  49  and the mixer head  29  can also be arranged vice versa, depending on the configuration of the batch mixer, e.g., the plunger head  49  can be arranged above the mixer head  29 . 
       FIG. 2  shows the batch mixer with the mixer head sealed on the mixer tank according to aspects of the present invention. More specifically, in  FIG. 2 , the cover  30  is placed on the mixer tank  5  with the one or more mixer blades  35  inserted in the mixing tank  5 . In this operational position, the arm  70   a  is locked onto the shaft  65  by the pin  75   b , and the mixer blades  35  are moved (e.g., rotated) by the high-torque motor  45 .  FIG. 2  further shows the plunger head  49  in the lowered position, with the arm  70   b , in embodiments, locked to the shaft  65  by the pin  75   c . Alternatively, the arm  70   b  can rest on the pin  75   c.    
       FIG. 3  shows the batch mixer with the plunger head sealed on the mixer tank according to aspects of the present invention. More specifically, in  FIG. 3 , the plunger head  49  is in the raised position, sealed on the mixer tank  5 . In this operational position, the arm  70   b  is in the raised position, and locked to the shaft  65  by the pin  75   b . Also, in this operational position, after the materials in the mixer tank  5  have had a sufficiently high residence time within the mixer tank  5 , the plunger  50  will begin to discharge the material through the die  20  of the mixer tank  5 . The flow rate of the material can be based on the valve setting  22 , as well as the force applied by the plunger  50 . As should be understood by those of skill in the art, the residence time of the materials will vary in accordance with the nature of the blending and compounding process. 
       FIG. 4  shows material being pushed from the batch mixer according to aspects of the present invention. In this operational stage of  FIG. 4 , the motor  60  will supply power to the plunger  50  in order to push material through the die  20 . More specifically, in embodiments, the plunger  50  is sealed on the mixer tank  5  and the motor  60  supplies power to the screw driven shaft  55  to lower the plunger  50  within the mixer tank  5 . In this way, the plunger  50  forces material  80  through the die  20  of the mixer tank  5 . In embodiments, the plunger  50  is a screw type plunger; however, it should be understood by those of skill in the art that other types of plungers are contemplated by the present invention. 
       FIG. 5  shows material  80  being discharged from the die  20  of the mixer tank  5  and guided through a water bath  85 . The water bath  85  is used to maintain a stable temperature of the material  80 .  FIG. 5  further shows the material  80  guided through a pellitizer  90 , which produces pellets  95  of different sizes and with different mechanical properties depending on the desired pellet type. In embodiments, the pelletizer  90  uses both mechanical force and thermal processes to produce the desired pellet properties. As a result, the discharged material  80  is transformed into pellets  95 . 
     As thus should now be understood, a method of mixing and blending material, e.g., polymeric material and/or food products, can be achieved with the batch mixer of the present invention. For example, material is placed within the mixer tank  5 , and the mixing head  29  is placed on the mixer tank  5 . The mixing head  29  is activated, and more specifically, the one or more mixer blades begin to mix the material within the mixing tank  5 . Once a desired residence time is achieved, the mixing head  29  is removed from the mixing tank  5 . For example, the mixing head  29  can be lifted in a vertical direction, and rotated away from the mixing tank. The mixing head  29  can be locked into place by a pin or other equivalent locking mechanism. Thereafter, the plunger head  49  is placed on the mixing tank, by moving it in the vertical direction and rotating it to align with the mixing tank  5 . The plunger mechanism, e.g., screw plunger, is activated in order to discharge the mixed material from the die  20 . The valve  22  can be adjusted in order to adjust the flow rate of the mixed material. The plunger mechanism can then be removed from the mixing tank  5 . 
     The foregoing examples have been provided for the purpose of explanation and should not be construed as limiting the present invention. While the present invention has been described with reference to an exemplary embodiment, changes may be made, within the purview of the appended claims, without departing from the scope and spirit of the present invention in its aspects. Also, although the present invention has been described herein with reference to particular materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

Technology Classification (CPC): 1