Batch mixer with plunger

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.

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.

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.

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 pelletizer 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. 1shows a batch mixer according to aspects of the present invention. More specifically,FIG. 1shows a batch mixer1having mixer tank5supported on support bases15a,15bby support bars10a,10b, 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 tank5has a diameter of about 10 cm and a height of about 20 cm; although other dimensions are contemplated by the present invention. The mixer tank5includes 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 tank5also includes a die20in fluid communication with the interior portion. The die20is structured to discharge materials from the interior portion of the mixer tank5, as discussed below. A valve22is provided for controlling the flow rate of the material being discharged through the die20. In embodiments, the die20can be customized to any desired shape such as a slit, annular, etc.

In embodiments, the mixer tank5further includes an opening25(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 tank5to prevent undesired chemical reactions from taking place within the mixer tank5. In alternate embodiments, the opening25is used to remove air or other gases from the mixer tank5, thus creating a vacuum.

As further shown inFIG. 1, the batch mixer1includes a mixer head29. The mixer head29includes a cover30, and one or more mixer blades35which are operable by a high-torque motor45. In embodiments, the high-torque motor45is connected to the one or more mixer blades35by a shaft40, in order to rotate the one or more mixer blades35. In this way, the high-torque motor45drives the shaft40thereby causing the one or more mixer blades35to mix and blend the materials, e.g., molten polymer blends and compounds or food products, within the mixer tank5. The one or more mixer blades35may be of different shapes and designs to ensure well mixed and/or blended materials. For example, the one or more mixer blades35can be paddle blades. In embodiments, the mixer blades35can also be gyrated in a rotational or partial rotational manner, as well as configurations which act as a vertical chopping.

Still referring toFIG. 1, the batch mixer1further includes a plunger head49. The plunger head49includes a plunger50attached to a screw driven shaft55. In embodiments, the screw driven shaft55is connected to a motor60in order to lower and raise the plunger50, when in the mixer tank5. In this way, in operation, the plunger50can discharge materials from the mixer tank5, through the die20. The plunger50is 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 die20.

In embodiments, the mixer head29and plunger head49are rotatably attached to a shaft65using an arm70aand an arm70b, respectively. Specifically, the mixer head29is connected to and spaced from the shaft65by the arm70aextending between the shaft65and the mixer head29, and the plunger head49is connected to and spaced from the shaft65by the arm70bextending between the shaft65and the plunger head49. In embodiments, the arms70a,70bare rotated manually; however, in alternate embodiments, the arms70a,70bcan be rotated automatically using a motor75. In further embodiments, the mixer head29and plunger head49move vertically along the shaft65. Similar to the rotational movement of the arms70a,70b, in embodiments, the vertical movement of the arms70a,70bmay be performed either manually or automatically. The vertical movement of the arms70a,70bis limited by the pins75a-75c(e.g., mechanical structures or limiters). The pins75a-75ccan also lock the arms70a,70bto the shaft65at certain operational positions. In alternate embodiments, other pins or other locking mechanisms are contemplated by the present invention.

More specifically, the pins75aand75blimit the movement of the mixer head29, in the vertical direction; whereas, the pins75band75climit the movement of the plunger head49, in the vertical direction. In embodiments, the pins75a-75ccan also lock the mixer head29and plunger head49at certain operational positions along the shaft65. In particular, the pin75acan lock the mixer head29in the raised position, and the pin75bcan lock the mixer head29in a lower position (i.e., when the mixer head29is sealed to the mixer tank5). Similarly, the pin75ccan lock the plunger head49in the lower position, and the pin75bcan lock the plunger head49in a raised position (i.e., when the plunger head49is sealed to the mixer tank5). As one of skill in the art should recognize, in embodiments, the plunger head49is located in the raised position (sealed to the mixer tank5), while the mixer head29is in the raised position (outside of and remote from the mixer tank); whereas the mixer head29is in the lowered position (sealed to the mixer tank5), while the plunger head49is in the lowered position (outside of and remote from the mixer tank). It should be understood by those of skill in the art, that the plunger head49and the mixer head29can also be arranged vice versa, depending on the configuration of the batch mixer, e.g., the plunger head49can be arranged above the mixer head29. Thus, the mixer head29and the plunger head49are configured to be interchangeably received within an inlet of the mixer tank5.

FIG. 2shows the batch mixer with the mixer head sealed on the mixer tank according to aspects of the present invention. More specifically, inFIG. 2, the cover30is placed on the mixer tank5with the one or more mixer blades35inserted in the mixing tank5. In this operational position, the arm70ais locked onto the shaft65by the pin75b, and the mixer blades35are moved (e.g., rotated) by the high-torque motor45.FIG. 2further shows the plunger head49in the lowered position, with the arm70b, in embodiments, locked to the shaft65by the pin75c. Alternatively, the arm70bcan rest on the pin75c.

FIG. 3shows the batch mixer with the plunger head sealed on the mixer tank according to aspects of the present invention. More specifically, inFIG. 3, the plunger head49is in the raised position, sealed on the mixer tank5. In this operational position, the arm70bis in the raised position, and locked to the shaft65by the pin75b. Also, in this operational position, after the materials in the mixer tank5have had a sufficiently high residence time within the mixer tank5, the plunger50will begin to discharge the material through the die20of the mixer tank5. The flow rate of the material can be based on the valve setting22, as well as the force applied by the plunger50. 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. 4shows material being pushed from the batch mixer according to aspects of the present invention. In this operational stage ofFIG. 4, the motor60will supply power to the plunger50in order to push material through the die20. More specifically, in embodiments, the plunger50is sealed on the mixer tank5and the motor60supplies power to the screw driven shaft55to lower the plunger50within the mixer tank5. In this way, the plunger50forces material80through the die20of the mixer tank5. In embodiments, the plunger50is 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. 5shows material80being discharged from the die20of the mixer tank5and guided through a water bath85. The water bath85is used to maintain a stable temperature of the material80.FIG. 5further shows the material80guided through a pelletizer90, which produces pellets95of different sizes and with different mechanical properties depending on the desired pellet type. In embodiments, the pelletizer90uses both mechanical force and thermal processes to produce the desired pellet properties. As a result, the discharged material80is transformed into pellets95.

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 tank5, and the mixing head29is placed on the mixer tank5. The mixing head29is activated, and more specifically, the one or more mixer blades begin to mix the material within the mixing tank5. Once a desired residence time is achieved, the mixing head29is removed from the mixing tank5. For example, the mixing head29can be lifted in a vertical direction, and rotated away from the mixing tank. The mixing head29can be locked into place by a pin or other equivalent locking mechanism. Thereafter, the plunger head49is placed on the mixing tank, by moving it in the vertical direction and rotating it to align with the mixing tank5. The plunger mechanism, e.g., screw plunger, is activated in order to discharge the mixed material from the die20. The valve22can be adjusted in order to adjust the flow rate of the mixed material. The plunger mechanism can then be removed from the mixing tank5.

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.