Patent Publication Number: US-2023150760-A1

Title: Large format container

Description:
PRIORITY 
     This disclosure claims priority to U.S. Provisional Application No. 63/278,853 with a filing date of Nov. 12, 2021. The priority document is incorporated by reference herein. 
    
    
     FIELD 
     This disclosure is directed to large containers having improved surface properties and reduced contamination, particularly to large containers formed through injection molding. 
     BACKGROUND 
     Intermediate bulk containers and other large volume containers can be used for the storage and transport of many different solid or liquid phase materials. These containers can be used for the storage or transportation of reactive chemicals such as various chemicals used in industrial processes such as manufacturing of semiconductor wafers and other contamination-sensitive applications. Polymeric large containers can be used due to cost and reactivity of the polymer compared to, for example, metallic container materials. Polymeric large containers are typically manufactured through rotational molding (roto-molding) or blow molding. While this allows inexpensive creation of large containers, these methods offer poor control regarding the characteristics of the inner surface or formation of particular features. Further, these containers typically need external support such as metal cages. 
     SUMMARY 
     This disclosure is directed to large containers having improved surface properties and reduced contamination, particularly to large containers formed through injection molding. 
     Polymeric large format containers can be formed by injection molding. The pressure applied during injection molding can produce a smoother, harder surface, reducing the surface area that can contribute contaminants and preventing there from being segments that could break off into the contained material. Further, the ability of injection molding to provide sections of differing thicknesses and to form finer internal details can allow the formation of additional features such as integral reinforcement ribs and internal features facilitating the use of the container contents such as rounded corners, sloping surfaces, and the like. Reinforcement ribs can reduce or eliminate the need for external support structures such as metal cages, thus reducing costs and risk of failure associated with those outside supports. 
     In an embodiment, an article includes a large format container. The large format container includes a polymeric main body including an internal surface defining an interior volume, wherein an arithmetic mean roughness of the internal surface of the polymeric main body is 0.75 µm or less. 
     In an embodiment, the polymeric main body includes a plurality of integral reinforcement ribs formed in the polymeric main body. 
     In an embodiment, the interior volume has a volume of between approximately 800 L and approximately 1300 L. 
     In an embodiment, the polymeric main body includes high density polyethylene (HDPE) 
     In an embodiment, the large format container further includes a fluoropolymer lining placed within the interior volume. 
     In an embodiment, an actual surface area of a reference area of the inner surface of the polymeric main body is less than an actual surface area of a reference area of an inner surface of a rotational or blow molded container, the reference area of the inner surface of the polymeric main body having the same size as the reference area of the inner surface of the rotational or blow molded container. 
     In an embodiment, the container sheds less particulate matter than a rotational or blow molded container. 
     In an embodiment, the polymeric main body includes one or more channels configured to receive a forklift. 
     In an embodiment, the polymeric main body is a single molded piece. 
     In an embodiment, the large format container further includes a lid configured to enclose the interior volume. In an embodiment, the lid includes one or more fill or dispense ports. In an embodiment, the large format container further includes a dip tube connected to one of the one or more fill or dispense ports, the dip tube extending into the interior volume. In an embodiment, the polymeric main body is configured such that a well is provided in the internal surface at a position below the dip tube. In an embodiment the lid is joined to the polymeric main body by a weld. In an embodiment, the internal surface includes a radiused section joining one or more sides of the internal surface to a bottom of the internal surface. 
     In an embodiment, a method of manufacturing the large format container includes forming the polymeric main body by injection molding. In an embodiment, the injection molding includes applying between approximately 700 bar and approximately 1100 bar of pressure where at least a portion of the internal surface contacts a mold surface. In an embodiment, the method further includes providing a lid and welding said lid to the polymeric main body. In an embodiment, the polymeric main body is formed as a single piece. 
    
    
     
       DRAWINGS 
         FIG.  1    shows a front view of a container according to an embodiment. 
         FIG.  2    shows a sectional view of the container of  FIG.  1   . 
         FIG.  3    shows a sectional view of a container according to an embodiment. 
         FIG.  4 A  shows an image of a surface of a container according to an embodiment. 
         FIG.  4 B  shows an image of a surface of a container according to a standard blow molding process. 
         FIG.  4 C  shows an image of a surface of a container according to a standard roto-molding process. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure is directed to large containers having improved surface properties and reduced contamination, particularly to large containers formed through injection molding. 
       FIG.  1    shows a front view of a container according to an embodiment. Container  100  includes container body  102 , with outer surface  104 . Optionally, manipulation features  106  can be formed on the container body  102 . A lid  108  can cover a top of container body  102 . 
     Container  100  is a large format container, that is, a single container that is capable of storing a large volume, for example, 500 L or more. A large-format container can be a container that requires mechanical assistance to handle and move the container when filled, for example due to containing too much mass to allow lifting by persons without such mechanical assistance. In an embodiment, container  100  is configured to accommodate a volume of between 500 L and 1500 L. One non-limiting example of a class of large format containers is intermediate bulk containers (IBCs). IBCs can be constructed according to standards for transportation containers, such as U.S. Department of Transportation regulations. Standards regarding IBCs can be based on regulations for containers for hazardous materials. In an embodiment, IBCs cannot exceed 3000 L of storage capacity. Container  100  can be used for storing materials such as solid or liquid materials. In embodiments, solid materials may be in the form of a powder. In an embodiment, container  100  can be used to store volatile or reactive materials. In an embodiment, container  100  can be used to store chemicals used in industrial processes such as the processing of wafers such as semiconductor wafers. 
     Container body  102  is a polymeric main body of the container  100 . Container body  102  can be made of any suitable polymeric material. In an embodiment, container body  102  is a melt-processable polymer. In an embodiment, container body  102  is made of high-density polyethylene (HDPE). Container body  102  can include one or more injection molded parts. In an embodiment, container body  102  includes a single injection molded piece. In an embodiment, container body  102  includes a plurality of injection molded portions fixed to one another, for example by way of a weld, such as a heat weld or any other suitable weld for the material used in container body  102 . Outer surface  104  is the exterior of the container body  102 . In embodiments, the outer surface  104  of container body  102  can include any suitable fine structure including, as a non-limiting example, relief undercuts. In an embodiment, an outer surface of container body  102  can possess a comparatively higher rigidity than a similar outer surface of a container body produced by roto-molding or blow molding. Manipulation features  106  can be formed on the container body  102 . The manipulation features can be any suitable mechanical features for engaging with a tool for manipulating container  100 . The manipulation features  106  can be in any suitable position for such features, such as being formed on outer surface  104  at one or more side walls of container body  102  and/or a bottom of container body  102 . Non-limiting examples of mounting features  106  include channels configured to receive tines of a forklift, projections configured to be engaged by machinery such that the machinery can better grip the container  100 , and the like. In the embodiment shown in  FIG.  1   , the mounting features  106  are channels configured to receive tines of a forklift, located at a bottom portion of the container body  102 . 
     Lid  108  can be provided to enclose the container body  102 . Lid  108  can be fixed or joined to container body  102  by any suitable method, such as a weld, mechanical fasteners, mechanical engagement features, or the like. 
       FIG.  2    shows a sectional view of a container according to  FIG.  1   . Container body  102  and its outer surface  104 , along with mounting features  106  continue to be visible in the sectional view of  FIG.  2   . In the sectional view of  FIG.  3   , an inner surface  110  of the container body  102  is visible. Inner surface  110  includes radiused portions  112  where the side walls  114  of inner surface  110  meet a bottom  116  of the inner surface  110  of container body  102 . A dip tube  118  can be seen extending from lid  108  to the interior space defined by inner surface  110 . 
       FIG.  3    shows a sectional view of a container according to an embodiment. Container  200  includes container body  202 , the container body having an inner surface  204  and an outer surface  206 . Optionally, a liner  208  can be located within the space defined by inner surface  204 . Reinforcement ribs  210  are formed on the outer surface  206 . A lid  212  is provided to enclose the container body  202  at one end. The lid  212  can include openings  214 . The openings  214  can be provided with a shipping cap  216  or a dispensing head  218 . The dispensing head  218  can include a dip tube  220  extending into the internal space within container body  202 . 
     Container body  202  is a polymeric main body of the container  200 . Container body  202  can be made of any suitable polymeric material. In an embodiment, container body  202  is a melt-processable polymer. In an embodiment, container body  202  is made of high-density polyethylene (HDPE). Container body  202  can include one or more injection molded parts. In an embodiment, container body  202  includes a single injection molded piece. In an embodiment, container body  202  includes a plurality of injection molded portions fixed to one another, for example by way of a weld, such as a heat weld or any other suitable weld for the material used in container body  202 . In the embodiment shown in  FIG.  3   , container body  202  is a cylindrical main body. In the embodiment shown in  FIG.  3   , container body  202  has an open end that can be closed by lid  212 . 
     Container body  202  has an inner surface  204  defining an interior space within the container body  202 . The inner surface  204  can be formed by a method resulting in high compaction of the inner surface  204  when compared to methods such as rotational or blow molding, such as injection molding. The compaction when forming inner surface  204  can increase a smoothness and/or a surface density of the inner surface  204  compared to rotational or blow molded containers. In an embodiment, the inner surface  204  is less likely to shed particulate compared to an inner surface of a rotational or blow molded container. In an embodiment, the inner surface  204  is formed such that it includes features such as rounded or radiused corners, sloping of the bottom, or any other suitable structural features that can facilitate addition, storage, or removal of materials from the internal space defined by inner surface  204 . 
     Liner  208  can be included in the internal space defined by inner surface  204  of container body  202 . Liner  208  can provide a layer between a material being contained within container body  202  and the inner surface  204 . Liner  208  can be, for example, a bag configured to be placed within container body  202 . The liner  208  can be made of any suitable material for interfacing with the material being contained within container body  202 . In an embodiment, the liner  208  includes a fluoropolymer. Liner  208  can be a flexible material. In an embodiment, liner  208  can at least generally conform to a shape of the inner surface  204  when liner  208  is placed into container  200  and liner  208  is filled with a fluid. In an embodiment, liner  208  can be inflated when located in container  200 , such that the liner  208  can be made to fill the space within container  200  prior to the filling of liner  208  with a material. In an embodiment, the liner  208  can be a gusseted three-dimensional (3-D) liner. In an embodiment, the liner can include a port at a bottom of the liner  208  such that liner  208  can be gravity drained. 
     Outer surface  206  is the exterior of container body  202 . Reinforcement ribs  210 , similar to reinforcement ribs  108  described above and shown in  FIG.  1   , can be formed on the outer surface  206 . Reinforcement ribs  210  can be portions of the container body  202  having a relatively increased thickness from the inner surface  204  to outer surface  206  compared to other portions of the container body  202 . The reinforcement ribs  210  can be formed integrally in container body  202 , for example by being defined by portions of a mold used in injection molding of container body  202 . The reinforcement ribs  210  can increase structural strength of the container body  202 , for example to resist shocks during transportation or to resist forces such as the weight of material contained within the container  202 . 
     Lid  212  can be provided to close an open top of container body  202 . In an embodiment, lid  212  can be fixed to the container body  202 , for example, by a weld. In an embodiment, lid  212  can be attached to the container body by a mechanical connection allowing subsequent separation, for example, by way of, as non-limiting examples, mechanical connection features such as threading, clamps or other mechanical connectors, fasteners such as bolts, and combinations thereof. Lid  212  can be made of any suitable material such as one or more polymer materials. In an embodiment, lid  212  is made of the same material as container body  202 . In an embodiment, lid  212  is injection molded from a melt-processable polymer material. 
     Lid  212  can include one or more openings  214 . The openings  214  are openings formed in lid  212  that can allow access to the contents of container body  202  while lid  212  is fixed or attached to container body  202 . The openings  214  can have any suitable shape for allowing access to the contents of container body  202 , for example to allow filling or removal of material from within container body  202 . The openings  214  can be shaped to interface with or receive any suitable tools for assisting in addition or removal of material from container  200 , for example to accommodate a particular dispensing tool such as dispensing head  218 . Shipping cap  216  is a cap configured to enclose an opening  214  on lid  212 . Shipping cap  216  can be sized and shaped such that it can interface with the opening  214  to close the opening  214 . Shipping cap  216  can be used during, for example, transit or storage of the container  200 . In an embodiment, shipping cap  216  can retain a stopper  222  in opening  214 . 
     Dispensing head  218  can optionally be placed in at least one opening  214  in a lid  212  of container  200 . Dispensing head  218  includes a connection interface outside of container  200 , allowing the dispensing head  218  to be connected to a device receiving material from inside the container  200 . Dispensing head  218  can include a dip tube  220  extending towards a bottom of a container such that the contents at the bottom of container  200  can be drawn into the dip tube  220  and brought through dip tube  220  to dispensing head  218  for removal from the container  200 . 
     The containers such as container  100  and container  200  described above and shown in  FIGS.  1  and  2    can be manufactured at least in part by injection molding. The injection molding can include formation of the container body, such as container bodies  102  and  202  as described above and shown in  FIGS.  1  and  2   . In an embodiment, the container body can be produced by injection molding as a single piece. In an embodiment, the container body can include multiple pieces that are each injection molded separately. The injection molding can include applying between approximately 700 bar and approximately 1100 bar of pressure where at least a portion of the internal surface contacts a mold surface. The injection molding can result in higher compaction of the polymeric material at the inner surface of the container body, resulting in a surface having greater smoothness and/or surface density compared to the inner surfaces of containers made by rotational or blow molding. The injection molding can produce an inner surface less likely to shed material or otherwise contaminate materials stored within the resulting container. Injection molding can allow thickness of the material to vary at different parts of the container body, allowing various structures to be integrally formed into the container body incorporating such changes in thickness. Non-limiting examples of such features include reinforcement ribs, rounding or radiusing of corners, or any other suitable features where a thickness of the container body varies by the particular position on the container body. In embodiments including a lid, such as container  200  including lid  212  described above and shown in  FIG.  3   , the lid can also be produced by a similar injection molding process. In embodiments including a lid, the lid can optionally be joined to the container body as part of the manufacturing process, for example by a weld. 
     The inner surfaces of containers according to some embodiments can include shapes and structural features to improve container performance. Non-liming examples include rounded or radiused corners, sloping bottom surfaces, wells, and other such features. These additional features can be structures that may not be present in containers manufactured by other methods such as rotational or blow molding which have less control over internal features. Such structures can include, as non-limiting examples, integral threading, bosses for facilitating fastening of objects or features to the vessel, handles, engagement features such as features for engaging with automation or machines such as forklifts or the like, relief features, and the like. 
     The increased compaction at the surface can result in a smoother, more consistent surface for the internal surface of the resulting container. The improved surface smoothness can be shown lower variation in height along the surface. In particular, containers formed by injection molding according to embodiments have significantly lower arithmetic mean roughness (R a ) compared to comparable containers formed by roto-molding or blow molding. The arithmetic mean roughness is an average of the absolute value of deviation from that average over the length of the reference line. Example containers were manufactured by way of injection molding, roto-molding, and blow molding of polyethylene (PE). Each of the example containers were manufactured having the same size and shape. Three samples of the interior surface of each of the example containers were measured and the arithmetic mean roughness R a  was obtained for each of the samples. The R a  values for the three samples of each example container were also averaged. The results of these measurements are provided in Tables 1-3 provided below in micrometers (µm) and micro-inches (µin).  
     
       
         
          TABLE 1
           
               
               
               
             
               
                 Injection Mold Surface 
               
               
                 Sample 
                 Ra µm 
                 Ra µin 
               
             
            
               
                 1 
                 0.6392 
                 25.17 
               
               
                 2 
                 0.7357 
                 28.96 
               
               
                 3 
                 0.7066 
                 27.82 
               
               
                 Avg 
                 0.6938 
                 27.32 
               
            
           
         
       
     
     
       
         
          TABLE 2
           
               
               
               
             
               
                 Blow Mold Surface 
               
               
                 Sample 
                 Ra µm 
                 Ra µin 
               
             
            
               
                 1 
                 1.8915 
                 74.47 
               
               
                 2 
                 1.9717 
                 77.63 
               
               
                 3 
                 1.9465 
                 76.63 
               
               
                 Avg 
                 1.9366 
                 76.24 
               
            
           
         
       
     
     
       
         
          TABLE 3
           
               
               
               
             
               
                 Roto-mold Surface 
               
               
                 Sample 
                 Ra µm 
                 Ra µin 
               
             
            
               
                 1 
                 1.1594 
                 45.65 
               
               
                 2 
                 1.1795 
                 46.44 
               
               
                 3 
                 1.1295 
                 44.47 
               
               
                 Avg 
                 1.1561 
                 45.52 
               
            
           
         
       
     
     The smoother surface provided by the injection molding further results in the same nominal area of the inner surface having a smaller actual surface area than the surfaces provided in blow molded or roto-molded containers. The samples of each of the containers discussed above, each having the same size, had the actual surface areas measured. The samples each had a size of 1416 µm x 1062 µm, or 0.056 in x 0.042 in. The actual surface area provided by each of the samples was measured using a surface characterization device (Keyence VK-X2000), and each sample measurement and an average of the samples for each method of manufacture are provided in the following tables:  
     
       
         
          TABLE 4
           
               
               
               
             
               
                 Injection Mold Surface 
               
               
                 Sample 
                 Surface Area µM 2 
 
                 Surface Area in 2 
 
               
             
            
               
                 1 
                 3214070 
                 0.00498 
               
               
                 2 
                 3341127 
                 0.00518 
               
               
                 3 
                 3403656 
                 0.00528 
               
               
                 Avg 
                 3319618 
                 0.00515 
               
            
           
         
       
     
     
       
         
          TABLE 5
           
               
               
               
             
               
                 Blow Mold Surface 
               
               
                 Sample 
                 Surface Area µM 2 
 
                 Surface Area in 2 
 
               
             
            
               
                 1 
                 3768660 
                 0.00584 
               
               
                 2 
                 3710162 
                 0.00575 
               
               
                 3 
                 3666048 
                 0.00568 
               
               
                 Avg 
                 3714957 
                 0.00576 
               
            
           
         
       
     
     
       
         
          TABLE 6
           
               
               
               
             
               
                 Roto-mold Surface 
               
               
                 Sample 
                 Surface Area µM 2 
 
                 Surface Area in 2 
 
               
             
            
               
                 1 
                 3396409 
                 0.00526 
               
               
                 2 
                 3424493 
                 0.00531 
               
               
                 3 
                 3412426 
                 0.00529 
               
               
                 Avg 
                 3411109 
                 0.00529 
               
            
           
         
       
     
     The different characteristics of the injection molded surface compared to can also be seen when the respective surfaces are inspected using a three-dimensional surface profiler to obtain an image of the surface.  FIG.  4 A  shows an image of a surface of a container according to an embodiment.  FIG.  4 B  shows an image of a surface of a container according to a standard blow molding process.  FIG.  4 C  shows an image of a surface of a container according to a standard roto-molding process. Each of  FIGS.  4 A- 4 C  are of an inner surface of a container according to the respective manufacturing method. The containers used as samples to obtain  FIGS.  4 A- 4 C  are of the same size and shape, and made from the same material as one another. The microscope images shown in each of  FIGS.  4 A- 4 C  are taken of their respective samples when at 10× magnification using a Keyence VK-X2000. As can be seen in  FIGS.  4 A- 4 C , the sample of the inner surface of the injection-molded container has a significantly smoother surface, whereas the inner surfaces resulting from blow molding and roto-molding of containers having the same size and structure and using the same material result in significantly greater surface variation and features that can break off into material stored within the container, trap some material within the container, provide additional surface area where contamination could leech into materials stored within the container, or the like. The improved flatness and consistency of injection molded samples according to an embodiment compared to roto-molded or blow molded standards thus reduces the risk of contamination and/or improves removal of materials from the container. 
     Aspects:
     Aspect 1. An article comprising a large format container, the large format container including a polymeric main body including an internal surface defining an interior volume, wherein an arithmetic mean roughness of the internal surface of the polymeric main body is 0.75 µm or less.   Aspect 2. The article according to aspect 1, wherein the polymeric main body includes a plurality of integral reinforcement ribs formed in the polymeric main body.   Aspect 3. The article according to any of aspects 1-2, wherein the interior volume has a volume of between approximately 800 L and approximately 1300 L.   Aspect 4. The article according to any of aspects 1-3, wherein the polymeric main body includes high density polyethylene (HDPE)   Aspect 5. The article according to any of aspects 1-4, further comprising a fluoropolymer lining placed within the interior volume.   Aspect 6. The article according to any of aspects 1-5, wherein an actual surface area of a reference area of the inner surface of the polymeric main body is less than an actual surface area of a reference area of an inner surface of a rotational or blow molded container, the reference area of the inner surface of the polymeric main body having the same size as the reference area of the inner surface of the rotational or blow molded container.   Aspect 7. The article according to any of aspects 1-6, wherein sheds less particulate matter than a rotational or blow molded container.   Aspect 8. The article according to any of aspects 1-7, wherein the polymeric main body includes one or more channels configured to receive a forklift.   Aspect 9. The article according to any of aspects 1-8, wherein the polymeric main body is a single molded piece.   Aspect 10. The article according to any of aspects 1-9, further comprising a lid configured to enclose the interior volume.   Aspect 11. The article according to aspect 10, wherein the lid includes one or more fill or dispense ports.   Aspect 12. The article according to aspect 11, further comprising a dip tube connected to one of the one or more fill or dispense ports, the dip tube extending into the interior volume.   Aspect 13. The article according to aspect 12, wherein the polymeric main body is configured such that a well is provided in the internal surface at a position below the dip tube.   Aspect 14. The article according to any of aspects 10-13, wherein the lid is joined to the polymeric main body by a weld.   Aspect 15. The article according to any of aspects 1-14, wherein the internal surface includes a radiused section joining one or more sides of the internal surface to a bottom of the internal surface.   Aspect 16. A method of manufacturing the article according to any of aspects 1-15, comprising forming the polymeric main body, wherein forming the polymeric main body includes injection molding.   Aspect 17. The method according to aspect 16, wherein the injection molding includes applying between approximately 700 bar and approximately 1100 bar of pressure where at least a portion of the internal surface contacts a mold surface.   Aspect 18. The method according to any of aspects 16-17, further comprising providing a lid and welding said lid to the polymeric main body.   Aspect 19. The method according to any of aspects 16-18, wherein the polymeric main body is formed as a single piece.   

     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.