Abstract:
A process for producing containers involves a tube and at least one separating partition, both formed from plasticized synthetic material. The partition extends within the tube. The tube and partition are extruded into an opened blow mold. The blow mold is then closed, and the tube is expanded by producing a pressure gradient that acts upon the tube. The pressure gradient is applied to expand the tube against the molding wall of the blow mold to form the container. The end of the tube that is the front end during the extrusion step and the front end of every separating partition are welded together by closing the opened blow mold, thereby closing the base of the container that is linked with every separating partition. The tube is expanded by adding blowing air from the end of the closed blow mold that is opposite to the container base and that is assigned to the container neck in such a manner that the blowing air has an expanding effect on both sides of the separating wall, thereby forming chambers in the container that are separate from one another.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a process for producing containers, in which a tube of plasticized synthetic material with at least one partition are formed from the synthetic material. The partition extends continuously in the interior of the tube. The tube and partition are extruded into an opened blow mold. The blow mold is closed. By producing a pressure gradient acting on the tube, the tube is expanded and is placed against the molding wall of the blow mold to form the container. 
     BACKGROUND OF THE INVENTION 
     A process of producing container with a partition is disclosed in DE 1 179 356 A1. In this process, when the blow mold is closed, the back end of the tube during extrusion is welded by weld edges located on the top of the blow mold in a hot-wire welding process. The synthetic material forming the container bottom is separated from the synthetic material which is leaving the overlying extruder means. The tube is expanded by supplying blowing air from the opposite lower end of the blow mold, specifically through the container neck molded on the lower end of the blow mold. 
     In the execution of the known process, the continued processing necessary for producing finished containers is rather elaborate. Thus, the container before filling must be removed from the blow mold which was opened beforehand and turned so that the container neck is at the top. Other working steps are then necessary for filling and producing a container closure. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a process which enables comparatively more efficient production of ready-to-use containers with an internal partition. 
     This object is achieved in a process according to the present invention by welding the end of the tube which is the front end during extrusion and the front end of the partition to one another by closing the opened blow mold in order to close the container bottom and connect the bottom to the partition. By expanding the tube by supplying blowing air from the end of the closed blow mold which is assigned to the container neck and which is opposite the container bottom, the blowing air on either side of each partition acts to expand and form chambers which are separate from one another in the container. 
     The top end of the mold cavity of the blow mold is assigned to the container neck. The ends of the tube and of the pertinent partition which are the front ends during extrusion provide the parts of synthetic material which reach the lower end of the blow mold, and are welded to form the container bottom according to the present invention. Accordingly, the expanded container can be further processed within the closed blow mold by carrying out the filling process for each inner container chamber through the container neck after expanding the container by means of blowing air introduced through the container neck on both sides next to each partition, without opening the blow mold or removing the container. 
     The filling process can be carried out by a combined blowing and filling mandrel or by a separate filling mandrel inserted into the container after withdrawing the blowing mandrel from it. 
     One special advantage of the process of the present invention is that, after filling the container, the container neck is finish-molded by an additional welding process which takes place with the blow mold still closed. In doing so, at the same time, it can be hermetically sealed with a closure formed by the welding process. This closing can take place by movable top welding jaws or head jaws located on the top of the blow mold. Any desired molding processes and/or closure processes can be carried out. For example, a closure which can be torn off at a scored site or disconnect can be formed, preferably in the form of a rotary lock closure. An outside thread could also be molded on the container neck to form a screw closure with a separate closure element. In the welding process carried out on the container neck, separate closures for each chamber of the container or a closure which closes all chambers of the container jointly can be formed. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
     FIGS. 1 and 2 are simplified schematic, side elevational views of a blow mold for forming a conventional container from an extruded plastic tube using conventional production methods, the blow mold being shown opened and closed, respectively; 
     FIG. 3 is a perspective view of a two-chamber container produced using the process according to the present invention, without added contents; 
     FIG. 4 is a schematically simplified, side elevational view in section of a nozzle arrangement of an extruder for executing the process according to the present invention; 
     FIG. 5 is an open, schematically simplified, side elevational view of a modified nozzle core of an extruder for carrying out the process according to the present invention; 
     FIG. 6 is a side elevational view of a two-chamber container in which a closure for both chambers is molded onto the container neck and can be opened by means of a twist-off lock; 
     FIG. 7 is a top plan view partially in section of the container of FIG. 6; 
     FIG. 8 is a schematically simplified side elevational view, similar to FIG. 1, of an apparatus for carrying out the process of the present invention for forming a two-chamber container, the blow mold being shown open; 
     FIGS. 9 to  11  are side elevational views of the apparatus of FIG. 8, with the blow mold being closed and with different process steps in the formation, filling and closing of the container, respectively; 
     FIG. 12 is a partial side elevational view of the neck part of a container produced using the process according to the present invention, a rotary lock closure being shown as the hermetic seal of the two container chambers; 
     FIG. 13 is another side elevational view of the container neck part of FIG. 12; and 
     FIG. 14 is a top plan view of the container neck part of FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 show a conventional apparatus used within the framework of the known bottelpack® system for producing a plastic container of the known type in a blow molding process. An extruder  1  extrudes a tube  3  of molten plastic material between the two mold halves  5  of a blow mold, shown in FIG. 1 in the open state. FIG. 2 shows the blow mold in the closed state, with the parts which mold for the main part of the container  12  to be formed from the tube  3  being moved together. The bottom-side weld edges execute a hotwire welding process on the bottom end of the tube  3  in order to close the tube  3  on a weld seam  9  (FIG.  2 ). By air supplied via a blowing mandrel  11 , the tube  3  is expanded into a container  12 , see FIG.  2 . Then, the filling process is carried out, for example, via the mandrel  11  shown in FIG. 1 or a separate filling mandrel. The top welding jaws  13 , which are movable on the blow mold, are now moved together, causing the container neck to be shaped, and in doing so optionally closing the container  12  by welding. In the examples shown in FIGS. 1 and 2, the weld jaws  13  form an outside thread  17  (FIG. 3) for a screw closure. 
     FIG. 3 shows, in schematic form, a container  19  produced using the process of the present invention. In contrast to the container  12  of FIG. 2, produced in the conventional manner, container  19  has a continuous inner partition  21  which divides the interior of the container  19  into two chambers  23  and  25  separated fluid-tight from one another. FIGS. 4 and 5 show the important parts of an extruder which, in interaction with a blow mold (not shown in these figures), is intended for carrying out the process of the present invention to produce a container which has an inner partition  21 , as shown in FIG.  3 . 
     FIG. 4 shows the end of the extruder  1  facing the blow mold (not shown). A nozzle ring  27  of the extruder receives a nozzle core  31  located coaxially to the lengthwise axis  29  of the nozzle. The tip  33  of the nozzle core, with the end area of the nozzle ring  27 , defines an annular outlet  35  from which extruded synthetic material emerges in the form of a tube. The molten synthetic material reaches the outlet  35  via an annular gap  37  formed between the nozzle ring  27  and the nozzle core  31 . As can be seen from FIG. 4, this annular gap  37  narrows at the transition between the core tip  33  and the part of the nozzle core  31  which follows upstream so that a retaining area  39  for the supplied synthetic material results. 
     The core tip  33  is screwed to the following, upstream part of the nozzle core  31  via a pin having an outside thread  40 . The surfaces of the core tip  33  facing one another and the following part of the nozzle core  31  are located at a distance from one another. The corresponding surface of the core tip  33  forms a funnel surface  41 . The facing surface of the remaining nozzle core  31  forms a conical surface  43 . These surfaces  41  and  43 , in the example shown, include an angle of incline of 65° or 60° relative to the lengthwise axis  29  of the nozzle, and form between themselves a guide for the synthetic material branched off from the annular gap  37 . The synthetic material enters the retaining area  39  between the surfaces  41  and  43 . Through holes in the pin of the core tip  33 , which has the outside thread  40 , this branched-off synthetic material travels into an outlet slot  45  formed on the front side of the core tip  33 . From there, the branched-off synthetic material emerges as a web extending crosswise within the extruded tube. After expansion of the tube, the web forms the partition  21  in the molded container  19  (FIG.  3 ). On either side next to the outlet slot  45 , i.e. on both sides of the plastic web emerging from the outlet slot  45 , in the end surface of the core tip  33 , there is one outlet opening  47  each for support air. The openings are connected to a central air channel  51  via branch lines  49  formed in the pin having the outside thread  40 . 
     The air supplied from the air channel  51  via the outlet openings  47  is intended as support air which simply prevents the collapse of the extruded tube and its cementing to the web which forms the partition  21 . The container is expanded in the blow mold in an additional working step by means of a blowing and filling mandrel. In an analogous arrangement to the outlet openings  47  of the core tip  33 , the blowing and filling mandrel has blow openings for supply of expanding, preferably sterilized blowing air. These blow openings can then also be used as fill openings for supply of the contents to the container chambers. 
     FIG. 5 shows the front end section of a modified nozzle core  31 , without the nozzle ring  27  which surrounds it. In contrast to the above described example, the nozzle core  31  does not have a front core tip screwed on to form a guide for the synthetic material to be branched off in cooperation with the following part of the nozzle core. Rather, in the embodiment of FIG. 5, the guide is a direct connection between the end-side outlet slot  45  and the annular gap which surrounds the nozzle core  31  via transverse holes  53 . Holes  53  extend in the nozzle core  31  transversely to the lengthwise axis and are connected to the inner end of the outlet slot  45 . The number and cross section of the transverse holes  53  are chosen such that the desired amount of synthetic material which is branched off from the outer annular gap emerges from the outlet slot  45  as the web which extends crosswise within the tube and which forms the partition  21 . As in the above described embodiment, on either side next to the outlet slot  45 , outlet openings  47  are provided for the support air which is supplied from the central air channel  51 . 
     In both embodiments shown in FIGS. 4 and 5, the thickness of the web emerging from the outlet slot  45  can be adjusted by choosing the ratio between the nozzle gap, i.e. the width of the annular gap  37  formed within the nozzle ring, and the width of the outlet slot  45 . In the example of FIG. 4, the distance between the funnel surface  41  and the conical surface  43  can be varied for this adjustment. Likewise, the amount of narrowing of the gap on the retaining area  39  can be varied. 
     The container  19  produced using the process of the present invention can, if so desired, be filled like conventional single-chamber containers while still within the blow mold and before the head-side, top welding jaws  13  are moved together on the blow mold to mold the container neck on the end side and optionally close it by welding. As indicated above, the two-chamber container  19  can be filled by a combined blowing and filling mandrel or by a filling mandrel which performs only the filling function. For each of the container chambers  23  and  25 , the mandrel has an outlet opening for the contents. The mandrel output openings are arranged offset in the same way, relative to the lengthwise axis of the filling mandrel, as is the case for the outlet openings  47  for support air on the nozzle core  31  of the extruder  1 . The outlet openings  47  discharge on either side next to the outlet slot  45  which forms the partition  21 . 
     As mentioned above, the shaping of the container neck of the container produced using the process of the present invention is performed by top movable welding jaws  13  on the pertinent blow mold, see FIGS. 1 and 2. In the example of the container  19 , shown in FIG. 3, the outside thread  17  is produced for a closure in the form of a screw cap (not shown) which closes both container chambers  23  and  25 . 
     Instead of making one such screw closure, a different type of closure can be made by the upper welding jaws  13  in the shaping of the container neck, as is known in the pertinent technology for single-chamber containers, for example, according to the bottelpack® system. As is shown in FIGS. 6 and 7, a rotary lock closure can be molded on the container neck  57 . The welding process is carried out such that the two chambers  23  and  25  are closed by twistoff lock  59 . Lock  59  can be separated at a disconnect  63 , formed as a scored site, by its being turned using its molded-on handle piece  61 . 
     FIGS. 8 to  11  show, in a highly simplified schematic, the progression of the process steps from the initial extrusion process of the synthetic material to complete production of a two-chamber plastic container, with two chambers  23  and  25  filled and hermetically closed by means of a rotary lock closure  73  (FIG.  11 ). By analogy with FIGS. 1 and 2, FIG. 8 shows the extrusion of the tube  3  with the inner partition  21  into the opened blow mold  5 , while FIG. 9 shows expansion into a container  19  by blowing air through the blowing mandrel  11  on either side of the partition  21  after the blow mold  5  has been closed. The bottom-side weld edges  7  carry out a hot-wire welding process by which the tube  3  is closed on the lower end and is joined to the end of the partition  21  on a weld seam  9 . 
     After withdrawing the blowing mandrel  11 , the filling mandrel  71  is inserted. The filling mandrel has one fill opening for each container chamber  23  and  25  which are separated by the partition  21 . The two chambers  23  and  25  are now filled, while the container  19  is still located within the blow mold  5  (FIG.  10 ). 
     After completed filling, the filling mandrel  71  is withdrawn and the top welding jaws  13  are moved together to carry out another welding process on the container neck  57 . The container neck  57  is finally molded and, in the example shown, is provided at the same time with a closure which hermetically seals both chambers  23  and  25 . In the example shown in FIG. 11, a rotary lock closure  73  is formed so that the container neck is made in the manner as shown in FIGS. 6 and 7, where a twist-off lock  59  with a handle piece  61  is shown. Such twist-off lock makes it possible to twist off the lock  59  at a disconnect  63 , by which the two chambers  23  and  25  of the container  19  are opened. 
     After filling the container and withdrawing the filling mandrel  71 , if so desired, insert parts can be placed in the container neck  57  before hermetically sealing the container. They can be functional parts such as a drop insert, a rubber plug, a hollow needle or other foreign part which can be inserted by a vacuum gripper before the welding jaws are moved together to weld around the insert part and at the same part form a hermetic closure. 
     FIGS. 12 to  14  show a form of the rotary lock closure  75  which is modified compared to FIGS. 6,  7 , and  11  for a two-chamber container in which each chamber is closed by a separate spherical closure element  76  and  77 . By means of a handle piece  79 , which is common to the two closure elements  76  and  77 , the two closure elements  76  and  77  can be twisted off at a disconnect  78  so that the two chambers of the container are opened. 
     While the present invention is described above based on the production of a two-chamber container, the nozzle core  31  of the extruder  1  could have more than one outlet slot  45  to extrude more than one plastic web. Within the plastic tube, several partitions can then be formed, to either side of which blowing air is supplied to mold a multichamber container in the pertinent blow mold. 
     While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.