Abstract:
Apparatus and method for deaerating and degassing of multi-component mixtures, such as polymers, accelerators, catalysts, fillers, color mixtures, and others in a continuously operating process. The configuration of the auger and flights thereon transporting the mixture through the apparatus and the inner configuration of the housing improve the mixing of the materials resulting in a homogenized cast polymer mixture.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to degassing and deaerating devices; and particularly to apparatus and method for deaerating and degassing multi-component mixtures, such as polymers, fillers and catalysts.  
           [0003]    2. Related Art  
           [0004]    It is known that, in the mixing of certain liquids, such as polymers, fillers, coloring agents, etc. that large amounts of gases, such as air bubbles, are generated in the mixing process. Air may be trapped in some raw material ingredients. Undesirable gases or air must thus be removed during mixing.  
           [0005]    One device for continuously degassing such mixtures is disclosed in U.S. Pat. No. 5,024,531 to Will. Another continuous vacuum processor is disclosed in U.S. Pat. No. 6,076,954 to Gisko. There is a need for such apparatus and method which improves the final mixture of polymers and other materials, such as fillers, removing essentially all air therefrom. Such a product would have physical properties that gives the final product a consistency that is better and easier to handle. Degassing has multiple benefits: Mixture improvement during processing, more complete mixing, possibility of ingredient percentages changing, greater range of process operation limits (perhaps ambient temperature or pressure). In addition, it is expected that there are additional end product benefits: Improved strength, life, color, texture, application, or other.  
         SUMMARY OF THE INVENTION  
         [0006]    It is an object of this invention to provide apparatus and method for deaerating and degassing multi-component mixtures, such as polymers, fillers, etc. to provide an air free final product.  
           [0007]    It is still further an object of this invention to carry out the foregoing object resulting in a product that is of better consistency than final products using other degassing and deaerating systems and that is easier to handle.  
           [0008]    These and other objects are preferably accomplished by providing apparatus for deaerating and degassing multi-component mixtures, such as polymers, accelerators, catalysts, fillers, color mixtures, and others in a continuously operating process. The configuration of the auger and flights thereon transporting the mixture through the apparatus and the inner configuration of the housing improve the mixing of the materials resulting in a homogenized cast polymer mixture. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 of the drawing is a cross-sectional view of the interior of the apparatus for carrying out the teachings of the invention; and  
         [0010]    [0010]FIG. 2 is a detailed cross-sectional view of a portion of the apparatus of FIG. 1 illustrating mixing of the components. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]    Referring now to FIG. 1 of the drawing, a coaxial multi-compartmented apparatus  10  is shown for deaerating and degassing a multi-component mixture. In the preferred embodiment of the invention, an inlet  11  is provided leading into a hollow gas tight cylindrical housing  12 . The solid ingredients of a multi-component mixture is fed therein from a feeder (not shown) as indicated by arrow  16  while any liquids required are fed into housing  12  through liquid inlet  300 . Such mixture may include polymers, accelerators, catalysts, fillers, coloring agents, etc. and is fed into inlet  11  in a continuously operated process. Optionally, the mixture may be made in batches in a machine or even manually mixed in a container. The mixture thus enters the feeding chamber portion  100  of housing  12 .  
         [0012]    An auger  14  is provided having a plurality of integrally connected spaced flights  15  for conveying the mixture from feeding chamber  100  to mixing chamber  301 . Auger  14  is rotated by a shaft  208  coupled to auger  14  in any suitable manner. Shaft  208  is mounted in bearing housing  211  rotating about one or more spaced bearing members  212 , at opposite ends of housing  211  (only one member  213  shown in FIG. 1). A motor (not shown) is adapted to rotate shaft  208  thus rotating auger  14 . Auger  14  is rotated in one direction only by the motor. This forms the driving portion of apparatus  10 . A dust seal portion  303  is provided between the driving portion and feeding area  100 . A flange  210  encircles housing  12 . The shaft portion  204  between shaft  208  and auger  14  may be stepped as shown. Flights  15  are of generally the same diameter within housing  12  within pressurizing chamber  17  of housing  12 .  
         [0013]    That is, flights  15  are generally the same diameter within the feeding and mixing chambers  100 ,  301 , then terminate in flight  305  at the terminal end of the pressurizing chamber  17 . Also, as seen, pressurizing chamber  17  leads into a sealing chamber  306  which in turn fluidly communicates with a vacuumizing chamber  307  leading into a second pressurizing chamber  308  which fluidly communicates with a final sealing chamber  309  at the exit nozzle  310  of apparatus  10 .  
         [0014]    The sealing, vacuumizing, pressurizing, and sealing chambers  306 ,  307 ,  308  and  309  are encompassed within housing  311  coupled to housing  12  by a resilient seal  312  which has a cylindrical portion  313  encircling the shaft of auger  12  within sealing chamber  306 . Housing  311  includes an integral tapered portion  314  tapering toward exit nozzle  310 . Exit nozzle  310  may also be of a resilient material and secured to tapered portion  314  by spaced nuts  315 ,  316 . Flights  19  within the sealing and vacuumizing chambers of  306 ,  307  are of a diameter conforming to the inner wall  25  of housing  311  which tapers to exit nozzle  310 . Flights  317 ,  318  are progressively lesser in outer diameter than flights  19  as shown thus providing pumping flights for apparatus  10 .  
         [0015]    A vacuum line  26  is provided coupled to bushing  27  in fluid communication with the interior of sealing chamber  306 . Hose  26  is adapted to be coupled at top to a suitable vacuum source (not shown) as indicated by arrow  319 . This hose  26  may be controlled by a conventional solenoid valve (not shown) and may be clear or transparent to view the interior thereof to observe the liquid flowing therethrough.  
         [0016]    The vacuum line  26  communicates with sealing chamber  306  where gases collect and are removed out of line  26 .  
         [0017]    A liquid inlet seal is provided at seal  312  leading into sealing chamber  306 . A liquid seal is also provided at the inner wall of exit nozzle  310  by seal  310 . The rear facing tapered portions of the flights act as mechanical wipers cleaning the various chambers and ports.  
         [0018]    A catalyst injector  202  may optionally be provided in fluid communication with vacuumizing chamber  307 . Injector  202  may be coupled to a tee connection fluidly coupled to a pair of air actuated toggle valves fluidly connected to and controlled by solenoid valves for controlling the same as is well known in the art. Flow control valves may also be used for controlling flow therethrough. Thus, a suitable catalyst may be injected into chamber  307  via injector  202  as indicated by arrow  320 .  
         [0019]    In operation, a mixture of liquids and solids, such as polymers, binding agents, coloring agents, catalyst, air or gasses, and fillers is fed into housing  12  via inlets  11  and  300  which inlets are in gas tight connection with the interior of housing  12 . This mixture may be premixed, if desired. The mixture may be fed therein in a continuous or batch feed or even fed in manually, if desired.  
         [0020]    The mixture enters into the feeding chamber  100  of chamber  10  and is fed by rotation of auger  14  to mixing chamber  301 . That is, the central core or auger  14  rotates and the rotation speed may be varied to control varying mixing conditions. The mixture goes from the mixing chamber  301 , to the pressurizing chamber  17  and into the sealing chamber  306  (see FIG. 2). Air and vapors or gases are eliminated continuously up and out of line  26  to a suitable source.  
         [0021]    Vacuumizing chamber  307 , which includes the sealing chamber  306 , slices the mixture flowing therethrough and the sliced mixture (see slices  401 ) releases air up and out tube  26  forming a space  317  within the vacuumizing chamber  307 , the deaerated material flowing against the inner wall  25  of vacuumizing chamber  307 , upon action of flights  19 , thus forcing the material to exit nozzle  310 .  
         [0022]    The finished product is completely mixed in a homogeneous manner. Air is removed out of tube  26  and the finished product has improved physical properties making it better and easier to handle. The process disclosed herein can be used to deaerate and degas any suitable multi-component mixture such as polymers, accelerators, catalysts, fillers, coloring agents, and others in a continuously operating process.  
         [0023]    The auger  14  has unique tapered flights leading into and out of the vacuumizing chamber  307  that assists in transporting the mixture and, after degassing and deaerating the mixture, discharging out of the discharge outlet  310 . As seen in the drawing, the outer periphery of the flights conform to the configuration of the inner wall of housings  12  and  311 . The apparatus in the drawing can be quickly and easily attached to preexisting equipment, such as a motor for rotating auger  14 , a feeder for introducing solids and liquids into inlets  11 ,  300 , a vacuum source coupled to tube  26  and a container pipe or other storage means coupled to outlet  310 . The apparatus can be easily cleaned.  
         [0024]    The low pressure of vacuumizing chamber  307  provides an area for collecting gases and vapors generated during the mixture process for removal from the apparatus  10 . The observation tube  26  can be used to inspect visually the interior thereof to watch the process taking place. The flights pump the material out of outlet  310 . A liquid seal is provided in sealing chamber  306  by seal  312  and, at sealing chamber  309  provided by resilient exit outlet  310  to maintain a gas tight seal. The flights act as a wipers to clean the interior of the vacuumizing chamber  307 .  
         [0025]    The motor (not shown) for rotating auger  14  may be a variable speed motor. The pitch of the flights are selected to provide a narrow pitch in the feeding and mixing chambers  100  for receiving the dry material filler, resin, and the like, and mixing the same while transporting the mixture into the vacuumizing chamber  307 . Here, the pitch of the flights is relatively wide to deaerate and degas the mixture and remove voids formed in the material and out of outlet  310  due to the vacuum control. The resulting degassed and deaerated mixture is moved over tapered portions of the flights of auger  14  and pushed via the flights out of nozzle  310 .  
         [0026]    In summary, apparatus  10  has an ingredient feeding chamber  100 , a mixing chamber  301 , a pressurized area or chamber  17 , a sealing chamber  306 , a vacuumizing chamber  307 , and an additional pressurized outlet area or chamber  308  terminating in a sealed area or chamber  309 .  
         [0027]    The coaxial mixer auger  14  rotates and ingredients are introduced into the mixing section of the apparatus  10 , and are blended together, under ambient pressure conditions. This may include entrained air. The mixing auger  14  blends, conveys and pumps the ingredients. Ingredients are moved forward by the auger  14  to a higher pressure area. Pressure is created by the rotating auger action.  
         [0028]    As the ingredients are moved forward, the pressure increases. A flow restriction is positioned at the end of the auger  14  between pressurizing chamber  17  and sealing chamber  306 . Material is pumped through the annular orifice and into the next chamber  307 . The material is expanded into the chamber  307 . The annular orifice is also a liquid seal  312 , which seals the vacuum into the vacuum chamber  307 . The vacuum chamber  307  is in communication with a vacuum source (not shown) via tube  26 .  
         [0029]    As discussed above with respect to FIG. 2, the material in vacuum chamber  307  is centrifugally spread, through a “slinging” action, to the perimeter of the auger  14 , and spread across the face of the vacuum chamber  307  inner diameter in a thin layer, and sheared repeatedly, mechanically, as seen in slices  401 , to release entrained air, or other gas bubbles. When these bubbles are mechanically released from the mixture, they migrate to the low pressure zone created by the communication with the vacuum source. This action removes air or gas from the mixture and chamber  307 . A mechanical vacuum seal (FIG. 1) is provided between seal  312  and the beginning of the tapered portion  314 .  
         [0030]    The auger  14  gathers up the mixture spread on the inner diameter of the vacuum chamber  307 , and begins to convey, and pump the mixture forward into another higher pressure area  308  at the discharge zone. Pressure gradient in this chamber  308  is from high vacuum (vacuum source inlet  26 ) to high pressure (material outlet  310 ). At the high pressure area, another liquid seal keeps the ambient pressure out of the chamber  307 . At the vacuum source a mechanical wiping action by the flights prevents clogging of the vacuum source port  26 .  
         [0031]    Although various modifications may be suggested by one skilled in the art, the scope of this invention should only be limited by the scope of the appended claims  
         [0032]    While the specification describes particular embodiments of the present invention, those of ordinary skill can devise variations of the present invention without departing from the inventive concept.