Patent Publication Number: US-2006005732-A1

Title: Blow-molded paintball and method of manufacture thereof

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to projectiles which are typically fired from a CO 2  or compressed air gas marker. More specifically, the invention relates to a paintball projectile structure formed by an outer blow-molded shell that fractures on impact with a target and leaving a pigmented marking agent contained within. This blow-molded paintball provides benefits not found in traditional gelatin paintballs. The process used to make the paintball is unique to paintball manufacturing and is a basis of this invention.  
      2. Background Art  
      Traditionally the shell of a gelatin paintball is formed with a pair of hemispheres of gelatinous material similar to that used to encase oral medicines such as cold capsules. As is the case with oral medicines, these gelatin shell paint balls are soluble in water. Upon striking the target, a paintball fractures to mark the target with coloring agent contained within the paintball shell. These gelatinous paintballs have the following negative attributes: Because the gelatin shell is soluble in water, the gelatin is easily affected by temperature and humidity conditions. The paintballs must be stored in almost perfect conditions to insure quality. Gelatin paintballs are also subject to irregular shelf life because of temperature and humidity conditions. These factors affect the performance of the paintball in many ways. First, the paintball becomes out of round and thus does not fly straight. Second, an out of round paintball is more likely to cause jamming problems within the paintball marker firing the paintball. Third, paintballs exposed to excessive humidity and/or heat, are less likely to break open and mark the target on impact. Fourth, paintballs exposed to cold or not enough humidity become brittle and are more likely to break inside the marker in the process of firing the paintballs. Fifth, gelatin paintballs, when made are left with a seam that cannot be removed and further contributes to the inaccuracy of the gelatin shell paintball when fired. Finally, the manufacturing process for gelatin paintballs must include a lengthy period within a special dehumidifying room to allow the paintballs to cure before they are ready for use. This extra step is not only expensive, but also very unpredictable.  
      U.S. Pat. Nos. 5,254,379 and 5,639,526 to Katsiopoulos et al disclose paintballs fabricated using a plastic shell. Although the preferred fabrication method is described as injection molding two hemisphere-shaped shell portions that are joined along a common seam, there is also reference to possible use of blow molding to form the shell. However, there is no suggestion of a blow-fill-seal process. Ordinary blow molding of a paintball shell would produce an empty thin shell with an aperture. Separate filling of the shell and sealing the aperture would be time consuming, labor intensive and subject the fragile empty shell to handling which could reduce yield and affect roundness.  
     SUMMARY OF THE INVENTION  
      The manufacturing process of the present invention may be referred to as Blow-Fill-Seal technology. Blow-Fill-Seal technology has already been in use for many years, usually to make products in the medical industry. In the present invention this technology is uniquely adapted to make paintballs.  
      As mentioned above, traditional gelatin paintballs come with many drawbacks. None of these drawbacks are found in paintballs formed using Blow-Fill-Seal technology. The material used to make the paintball shell may be biodegradable resin that is not susceptible to temperature and humidity changes. This is a benefit that allows longer shelf life and allows consumers to use the product in extreme cold, heat and humidity conditions without affecting the performance of the product. The paintball itself is formed with a much more spherical nature/characteristic thus allowing the paintball to fly farther and much more accurately when fired from a CO 2  or compressed air marker. The manufacturing process is simplified and shortened compared to manufacture of traditional gelatin paintballs. There is no longer a need for dehumidifying rooms to let the paintball cure after manufacturing. Paintballs formed using Blow-Fill-Seal technology are completely finished as they leave the machine. The harness/breakability of the paintball is also easily controlled in the manufacturing process by adjusting the amount of resin used to make the outer paintball shell.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The aforementioned objects and advantages of the present invention, as well as additional objects and advantages thereof, will be more fully understood hereinafter as a result of a detailed description of a preferred embodiment when taken in conjunction with the following drawings in which:  
       FIG. 1  illustrates the open paintball molds receiving a parison from an extruder head;  
       FIG. 2  illustrates the closed paintball molds and the parison being cut;  
       FIG. 3  illustrates the closed molds at the filling station after the molten parison has formed a paintball ball shell; and  
       FIG. 4  illustrates the fully molded, filled and sealed paintball after the sealing molds have sealed the remaining aperture.  
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT  
      Blow-fill-seal technology, originally developed in Europe in the 1930&#39;s and introduced in the United States in the 1960&#39;s, has emerged as a preferred method for aseptic packaging of pharmaceutical and healthcare products due to unrivaled flexibility in container design, overall product quality, product output and low operational costs. The multi-step process of blow molding, aseptic filling and hermetic sealing of liquid products may be achieved in one sequential operation on a compact, automated machine frame with fill volumes ranging from 0.1 milliliter (ml) to 1,000 ml.  
      A variety of polymers may be used in the process, low and high-density polyethylene and polypropylene being the most popular. The innate ability to form the container/closure during the actual aseptic packaging process allows for custom design of the product to meet the specific needs of the application.  
      Recent advancements in machine design allow for insertion of pre-molded, pre-sterilized components to be molded into a container creating additional design options to create multi-use product containers. Furthermore, the blow-fill-seal process flow is normally impacted by only two raw materials, product and polymer, that are each processed inline, thereby making the process amenable to large uninterrupted batch sizes, some in excess of 500,000 units, and fill durations of up to 120 hours. The net effect is routinely an increase in production efficiency and a subsequent decrease in operational costs for the user.  
      The blow-fill-seal process is a robust, advanced aseptic processing technology, recognized by worldwide regulatory authorities for its inherent operational advantages over conventional aseptic production. Blow-fill-seal systems offer a unique combination of flexibility in packaging design, low operating cost and a high degree of sterility assurance. The machines require a minimum number of operating personnel and have a relatively small space requirement.  
      The blow-fill-seal manufacturing process practiced by the blow-fill-seal machines known to the prior art is generally considered to be a preferred process for manufacturing pre-filled plastic syringes. In such blow-fill-seal manufacturing process, a semi-molten, hollow, cylindrical plastic parison is extruded downwardly between cavities provided in a pair of open and opposed main molds and open and opposed pair of gripping jaws mounted for reciprocal movement toward and away from each other; the mold cavities are shaped complementarity to the pre-filled plastic container to be formed. The gripping jaws grip the upper portion of the parison and the main molds are then closed around the lower portion of the plastic parison to seal the bottom of the container after which a cutting knife severs the upper portion of the parison to separate it from the extruder. Pressurized air is then injected into the severed lower parison portion to force lower portions of the parison outwardly against the walls of the main mold cavities to partially form the container but leaving the partially formed product open at the top for subsequent liquid filling. Thereafter, a liquid fill nozzle is advanced above, or slightly into, and is injected or dispensed into the partially formed plastic container after which the filling nozzle is withdrawn and the sealing molds are closed to seal the upper portion of the parison and complete the forming or molding of the pre-filled plastic container.  
      Blow-Fill Seal Process  
      Shell Molding  
      Thermoplastic is continuously extruded in a tubular shape. When the tube reaches the correct length, the mold closes and the parison is cut. The bottom of the parison is pinched closed and the top is held in place with a set of holding jaws. The mold is then transferred to a position under the filling station.  
      Shell Filling  
      The nozzle assembly lowers into the parison until the nozzles form a seal with the neck of the mold. Shell formation may be completed by applying a vacuum on the mold-side of the shell and blowing sterile filtered air or other gas into the interior of the shell. An electronic fill system delivers a precise amount of dye into the shell. The nozzles then retract into their original position.  
      Shell Sealing  
      Following completion of the filling process, the top of the shell remains semi-molten. Separate seal molds close to form the top and hermetically seal the shell. The molds open and the paintball is then conveyed out of the machine.  
      The method of the present invention may be carried out in a variety of blow-fill-seal machines currently employed to manufacture containers for pharmaceuticals and syringes. They key change is to employ mold halves having a spherical interior shape to form a paintball shell and seal mold halves to seal the shell after it=s filled, but without corrupting its spherical surface. The accompanying figures are used to generically explain the blow-fill-seal process for paintballs, it being understood that there are numerous variations that may be made depending upon machine implementation.  
      As seen in FIGS.  1  to  4 , a typical blow-fill-seal apparatus  10  that may be used to fabricate paintballs, comprises main mold halves  12  and  14  and seal mold halves  16  and  18 . Apparatus  10  also comprises parison grippers  20  and  22 , cutter  24  and extruder head  26 .  
      As shown in  FIG. 1 , initially the main mold halves  12  and  14  are separated and positioned beneath extruder head  26  to permit the head to extend a parison  28  of molten resin between the interior surfaces of the halves. After the parison  28  reaches the lower ends of the halves, the halves are moved into mutual engagement to form a full spherical interior  15  trapping a tubular segment of the parison therein.  FIG. 2  illustrates the action of the parison grippers  20  and  22  which limit the flow of resin from head  26  when they come in contact with the bulbous formation of the resin above the mold. Cutter  24  then slices through the enlarged portion of the parison  28  thereby permitting a station change as shown in  FIG. 3 .  
       FIG. 3  shows the mold positioned beneath an inflating and filling tube  35 . Tube  35  employs a pressurized gas (i.e., air, nitrogen) to expand the mold resin parison against the spherical interior  15  of the main mold halves  12  and  14 , thereby forming a spherical paintball shell  30 . In some blow-fill-seal machines, the main mold halves may have small vacuum channels in their walls  25  to assist in expanding the parison to form the shell. Tube  35  then fills the shell  30  with the desired fill commonly employed in conventional paintballs. The contents  32  are injected through an unsealed shell aperture  29  shown in  FIG. 3 .  
      After the shell is filled, the sealing mold halves  18  and  16  are then actuated as shown in  FIG. 4 . The aperture  29  is sealed closed, thereby leaving a fully formed spherical shell filled with dye. A flash  34  may be formed at the lower end of the main mold halves  12  and  14 . After the completed formation, filling and sealing of the paintball, the molds are separated and the flash  34  is removed using conventional flash removal techniques.  
      It will be understood that although FIGS.  14  illustrate blow-fill-seal fabrication of a unitary paintball, a typical process employed in the present invention would produce numerous paintballs in each cycle simultaneously so that economy of mass production can be realized in a high volume process.  
      Having thus disclosed an exemplary embodiment of the method of the present invention, it will be understood that there may be various modifications and additions in an actual blow-fill-seal machine employed to carry out the steps described herein for the production of paintballs. Accordingly, the scope hereof is to be limited only by the appended claims and their equivalents.