Expanded plastic container and method for manufacturing

Abstract

The invention relates to a stretch-blow-molded plastic container (100) with a container body (20), which forms a filling volume (F), and a handle (21), which is formed on the container body. In order to form the handle (21), a first sub-region (221) of a first wall (22) of the container body (20) is bonded to a second sub-region (231) of a second wall (23) of the container body (20) lying opposite the first wall (22). The filling volume (F) extends circumferentially about the bonded connection. A bead (31) made of melted material is arranged within the filling volume between the first wall (22) and the second wall (23).

Description

[0001] Stretch-blown plastic container and method for manufacturing

[0002] The present invention relates to a stretch-blown plastic container and a method for producing a bead from molten material according to the preamble of the independent claims.

[0003] A variety of plastic containers are known from the state of the art.

[0004] There are various different processes for producing plastic containers, particularly plastic bottles. Their application depends not least on the plastics used. Plastic containers are usually produced using a blow molding process, in which plastic containers, for example plastic bottles, are inflated into their final shape using excess pressure in a blow mold. There are different processing techniques used in blow molding, the most notable of which are extrusion blow molding, injection blow molding and injection stretch blow molding. In the extrusion blow molding process, a single or multi-layer plastic tube is hot-extruded, introduced into a blow mold and inflated into a plastic container using a blow mandrel inserted into a mold cavity of the blow mold. The injection blow molding process is a combination of injection molding and blow molding.In this process, a preform is first produced in an injection mold using an injection mold. The preform is removed from the injection mold, conditioned if necessary, and placed into the cavity of a blow mold where it is then inflated using excess pressure to the shape specified by the mold cavity. In the injection stretch blow molding process, the preform placed in the mold cavity is additionally stretched with a mandrel during the blow molding process. The preform can be inflated immediately after its production using the injection molding process. In alternative manufacturing processes, the further processing of the preforms can also take place spatially and / or temporally separately from the production of the preform. Finally, it should also be mentioned that the preforms can also be produced using an impact molding process or an extrusion blow molding process.

[0005] In addition, plastic containers with an integral handle have become known. It has been found that plastic containers are more readily accepted by users when they have a handle that is separate from the rest of the container and can be completely grasped by the hand. A relatively simple solution for providing such handles is achieved by having the plastic container with a reach-through opening that penetrates the container body.

[0006] WO 2017 / 211540 A1 discloses a plastic container, in particular made of PET, which has a reach-through opening and a corresponding handle. The reach-through opening of the plastic container of WO 2017 / 211540 A1 is achieved by welding two wall sections together after stretch blow molding of the plastic container, and then cutting out a corresponding section from the container separated by the weld seam.

[0007] A comparable plastic container made of polypropylene is known under EP 1 835 461 A2.

[0008] Both plastic containers have a connecting seam located in the reach-through opening. This can potentially create a weak point in the plastic container, which can be disadvantageous, particularly in mail-order businesses, where product handling is not fully controllable and products are repeatedly subjected to loads exceeding their permissible weight. Therefore, the object of the invention is to remedy at least one or more disadvantages of the prior art. In particular, a plastic container is to be provided that is stable and can withstand higher loads.

[0009] This object is achieved by the devices and methods defined in the independent patent claims. Further embodiments emerge from the dependent patent claims.

[0010] A device according to the invention relates to a stretch-blown plastic container with a container body forming a filling volume. The plastic container has a handle formed on the container body. To form the handle, a first partial region of a first wall of the container body is materially connected to a second partial region of a second wall opposite the first wall, so that the filling volume extends circumferentially around this materially connected connection. In other words, a single, coherent filling volume is created within the container body.

[0011] Within the filling volume between the first wall and the second wall there is arranged a bead of molten material.

[0012] The placement of a bead between the first and second walls reduces the stress concentration at the junction between the first and second walls. This makes the plastic container more stable and less susceptible to impacts.

[0013] The bead can be formed as part of a weld seam. This allows an integral connection to be created between the bead, the first wall, and the second wall, and accordingly the weld seam. The bead can connect the first wall and the second wall in a region in which the first wall and / or the second wall has a curvature.

[0014] In areas where the walls are curved, they are particularly susceptible to peeling under external forces.

[0015] By arranging a bead in this area, the corresponding effects can be reduced, which overall leads to greater stability of the plastic container.

[0016] The bead may connect the first wall and the second wall in a region in which the first wall is spaced from the second wall.

[0017] Even in areas where gaps or spaces form between the walls to be joined, the corresponding connection between these walls is more susceptible to external influences, particularly to the effects of force. By providing a bead in the area of ​​a gap between the first wall and the second wall, particularly in the area of ​​a gap, the susceptibility to failure of the container can be counteracted.

[0018] Preferably, the bead projects beyond the surfaces of the first wall and the second wall directed in the direction of the filling volume.

[0019] By such an arrangement, a depression or a notch between the first wall and the second wall can be completely prevented and the connection of the first wall and the second wall in this area can be reinforced.

[0020] Preferably, the bead is formed circumferentially along the first partial region and / or the second partial region. In other words, the bead forms a circumferentially closed connection between the first wall and the second wall. A corresponding gap between the first wall and the second wall is thus sealed off from the filling volume.

[0021] The first partial area and the second partial area can be separated on the side of the filling volume facing away from the material connection, so that a through opening is formed.

[0022] The plastic container may be made of a polymer with a dipole, in particular PET.

[0023] Such polymers are particularly suitable for high-frequency welding because their molecules can be excited particularly well.

[0024] A further aspect of the invention relates to a method for producing a bead of molten material between a first wall and a second wall of a container body opposite the first wall. The method comprises the steps:

[0025] - Providing a stretch-blown plastic container with a container body forming a filling volume,

[0026] - materially connecting a first partial area of ​​the first wall of the container body to a second partial area of ​​the second wall to form a handle formed on the container body, so that the filling volume extends circumferentially around this materially bonded connection.

[0027] The material-to-material connection is created by high-frequency welding or friction welding. During the welding process, pressure is exerted on the welding zone so that at least part of the molten metal created during the welding process is forced out of the welding zone to form the bead. High-frequency welding and friction welding are processes which make it possible to melt the elements to be joined in the area of ​​their contact. The pressure exerted on the walls to be joined forces the molten metal thus created to the outside from the inside or from the area between the first wall and the second wall, creating a bead which is an integral part of the weld seam and, together with the weld seam, has a correspondingly high level of strength.By appearing as a melt, this bead can also bond with the areas of the first wall and the second wall which, for example, do not lie exactly against each other and / or cannot be directly reached by the corresponding welding devices.

[0028] Preferably, the melt is pressed in the direction of the filling volume.

[0029] Accordingly, the bulge also arises in the area of ​​the container which is directed towards the filling volume and in which the first wall and the second wall meet.

[0030] At the same time, part of the melt is also pushed in the opposite direction, so that the first wall and the second wall also connect in areas that are facing away from the filling volume.

[0031] Preferably, the melt is pressed out of the welding zone until a bead formed from the melt connects the first wall and the second wall in a region in which the first wall and / or the second wall has a curvature.

[0032] This allows the gap between the first and second walls to be filled with a bead, reducing the notch effect. Peeling of the first wall from the second wall in the event of excessive force can be prevented for a longer period.

[0033] Preferably, the melt is pressed out of the welding zone until a bead formed from the melt connects the first wall and the second wall in a region in which the first wall is spaced from the second wall.

[0034] This also allows a gap between the first and second walls to be filled with a bead, reducing the notch effect. Peeling of the first wall from the second wall in the event of excessive force can be prevented for a longer period.

[0035] It can be provided that the melt is pressed out of the welding zone until a bead formed from the melt projects beyond the surfaces of the first wall and the second wall directed in the direction of the filling volume.

[0036] The surface of the first wall and the surface of the second wall, as well as a surface of the bead, form a common surface that is, in particular, free of notches and / or depressions. Such a common surface is particularly resistant to force and can resist peeling processes for a long time.

[0037] Before the first partial area is joined to the second partial area, the first partial area and the second partial area can be brought into contact with one another using movable stamps within a blow mould.

[0038] This makes it possible to define the subsequent shape of the plastic container over a wide range and to bring the partial areas of the first wall and the second wall to be joined into a shape that is advantageous for the welding process.

[0039] After the first partial area and the second partial area have been joined together in a materially integral manner, the first partial area and the second partial area can be separated on the side of the filling volume facing away from the materially integral connection, so that a through opening is formed.

[0040] This allows for the creation of a container that is visually appealing and pleasant to the touch, with a handle that the user can fully grasp, allowing the container to be held securely.

[0041] The invention is explained below using schematic figures based on an exemplary embodiment. It shows:

[0042] Figure 1: A perspective view of a plastic container;

[0043] Figure 2A, 2B: a schematic view of a blowing process;

[0044] Figure 3: a sectional view through a plastic container;

[0045] Figure 4: a sectional view through a plastic container;

[0046] Figure 5: a detailed view from Figure 4;

[0047] Figure 6: the detailed view from Figure 5;

[0048] Figure 7: the detailed view from Figure 5;

[0049] Figure 8: the detailed view from Figure 5.

[0050] Figure 1 shows a plastic container 100 with a container body 20 and a handle 21. The handle 21 is formed as an integral part of the container body 20. The plastic container 100 has an unspecified opening at the top and a container base facing away from this opening. The container base and the opening close the container body 20.

[0051] The container handle 21 is arranged such that it can be completely grasped. For this purpose, a through-opening 40 is provided on the container body 20. A filling volume extends around the through-opening 40. The filling volume fills the container body 20 and the handle 21. In other words, the interior of the handle 21 is connected to the filling volume.

[0052] Figures 2A and 2B schematically show a blow molding process. A preform 101 is inserted into a mold 102. At this point, the preform 101 is already tempered. The mold 102 essentially has the future outer contour of the plastic container. As can be seen in Figure 2B, to inflate the preform, a stretching rod 103 is inserted into the preform 101, and the preform 101 is stretched accordingly. At the same time, a hot blowing medium is blown into the preform 101 at excess pressure, allowing it to adhere to the inner surfaces of the blow mold 102.

[0053] Figure 3 shows a cross-section along line AA of Figure 2B, wherein the cross-section is shown in chronological order after the complete inflation of the container 100. The container body 20 has a first wall 22 and a second wall 23 opposite the first wall 22. The first wall 22 has a partial region 221, which is shaped in relation to an envelope curve toward the interior of the container body 20. The second wall 23 also has a partial region 231, which is shaped in relation to an envelope curve toward the interior of the container body 20. The contour of the cross-section, as shown in Figure 3, can be created by the blow mold 102 and the corresponding inflation. The partial regions 221 and 231 are spaced apart from one another so that the region of the future handle, on the right in the present figure, can also be completely inflated. The walls

[0054] 22 and 23 limit a filling volume F .

[0055] Figure 4 shows a cross-section analogous to the cross-section according to Figure 3. Figure 4 shows that the partial areas 221 and 231 are deformed with punches 104 and 105 so that these partial areas 221 and 231 are brought into contact with one another. This process can preferably be carried out while the inflated container is still inside the blow mold. This makes it possible, for example, to maintain an overpressure within the filling volume F so that the walls of the container body are pressed against the inner surfaces of the blow mold so that the remaining contour of the container body remains correspondingly shaped. The filling volume F is still formed within the handle 21 and the remaining container body 20.

[0056] Figure 5 shows a detailed view X from Figure 4. In this detailed view, a part of the first partial area 221 and a part of the second partial area 231 are illustrated. The partial areas 221 and 231 are brought into contact with each other and, in particular, prepared for subsequent welding. The partial areas 221 and 232 each extend into the walls 22 and

[0057] 23 over .

[0058] The partial areas 221 and 231 are joined together by high-frequency welding. Two electrodes (not shown in detail here) press the partial areas 221 and 231 together so that the material lying in between is melted. The area that is pressed together is referred to here as welding zone 32. This concerns an area that is directly exposed to the electrodes. The melting creates a weld seam 30. The superimposed surfaces of the partial areas 221 and 231 therefore soften in the area of ​​the welding zone and a melt is created which forms a weld seam. The electrodes press the partial areas 221 and 231 together with high pressure. In the illustration according to Figure 5 on the right, the partial areas 221 and 231, or the walls 22 and 23, each have a curvature in the area in which the handle 21 widens (see Figure 4).In the area of ​​this curvature, the surfaces 222 and 232 of the walls 22 and 23 begin to distance themselves from each other, so that a gap is created.

[0059] Figure 6 shows a detailed view corresponding to Figure 5 at a later point in the process. Due to the pressure applied by the electrodes, at least part of the melt is pushed out of the weld seam 30, in particular from the weld zone 32 (see Figure 5), in the direction of the filling volume F, so that a bead 31 forms between the first wall 22 and the second wall 23. This makes it possible to create a joining zone even in an area that cannot be directly acted upon by the electrodes. The distance between the weld seam 30, and in this case the bead 31, and a force application point on the walls 22 or 23 is reduced. This means that the connection can withstand greater loads.

[0060] 6, the welding process can also be continued. The bead 31 then fills a gap created by the curvature of the walls 22 and 23, which immediately leads to a reduction in the notch effect between the walls 22 and 23. The bead 31 closes the gap between the first wall 22 and the second wall 23 in the direction of the filling volume. The bead 31 therefore connects the first wall 22 and the second wall 23 in a region in which the first wall 22 and the second wall 23 have a curvature. In this region, the first wall 22 is also spaced from the second wall 23. The bead 31 therefore connects the walls 22 and 23 in this region and bridges a gap between the first wall 22 and the second wall 23.

[0061] Figure 7 shows a detailed view corresponding to Figure 6 at a later point in the process, when the process is still being continued. By further melting and by the pressure of the electrodes on the partial areas 221 and 231, the melt was pushed to both sides of the original weld seam 30 (see Figure 5). Due to the existing arrangement of the walls 22 and 23 and the corresponding partial areas 221 and 231, a large part of the melt of the weld seam 30 has been pushed towards the open side of the gap between the first wall 22 and the second wall 23 and accordingly in the direction of the filling volume F. The bead 31 almost fills the gap between the first wall 22 and the second wall 23. The notch effect, which occurs due to the existing geometry, is further reduced because the attack surface and the depressions in the area of ​​the gap are reduced.The bead 31 almost fills the gap in the direction of the filling volume F .

[0062] Figure 8 shows a detailed view corresponding to Figure 7 at a later point in the process, when the process is still being continued. By further melting and by the pressure of the electrodes on the partial areas 221 and 231, the melt was pushed even further out on both sides of the original weld seam 30 (see Figure 5). The bead 31 created here projects beyond the surfaces 222 and 232 of the walls 22 and 23, which are directed in the direction of the filling volume F, so that the walls 22 and 23 are reinforced in the region of the gap and thus in the region of their curvature.

[0063] All designs of the weld seam 30 and the bead 31, as described for Figures 6 to 8, reinforce the connection between the walls 22 and 23, increase the strength of the connection, and, in particular, reduce the susceptibility to failure. Impacts on the plastic container can cause the pressure within the filling volume F to become relatively high. Due to the reduced stress concentration and the filling of the gap with the bead 31, the influence of such impacts on the weld seam 30, as well as on the connection between the first wall 22 and the second wall 23, can be reduced.

[0064] It is understood that the bead 31 can be formed circumferentially around the partial regions 231 and 221 and accordingly closes them off from the filling volume F. The associated weld seam 30 thus forms a continuous, circumferential closure of the partial regions 221 and 231 with respect to the container body 20. The weld seam forms a material-fit connection. The first partial region 221 and the second partial region 231 can be separated on the side of the filling volume facing away from the material-fit connection, so that a through opening 40 is formed (see Figure 1).

Claims

Patent claims 1. Stretch-blown plastic container (100) with a container body (20) forming a filling volume (F) and a handle (21) formed on the container body, wherein, for the formation of the handle (21), a first partial area (221) of a first wall (22) of the container body (20) is materially connected to a second partial area (231) of a second wall (23) of the container body (20) opposite the first wall (22), such that the filling volume (F) extends circumferentially around this materially connected joint, characterized in that within the filling volume (F) between the first wall (22) and the second wall (23) a bead (31) of molten material is arranged.

2. Plastic container (100) according to claim 1, characterized in that the bead (31) is formed as part of a weld seam (30).

3. Plastic container (100) according to claim 1 or 2, characterized in that the bead (31) connects the first wall (22) and the second wall (23) in a region in which the first wall (22) and / or the second wall (23) has a curvature.

4. Plastic container (100) according to one of claims 1 to 3, characterized in that the bead (31) connects the first wall (22) and the second wall (23) in an area in which the first wall (22) is spaced apart from the second wall (23).

5. Plastic container (100) according to one of claims 1 to 4, characterized in that the bead (31) has the surfaces (222, 232) directed in the direction of the filling volume. The first wall (22) and the second wall (23) project beyond the filling volume. A plastic container (100) according to any one of claims 1 to 5, characterized in that the bead (31) is formed circumferentially along the first sub-region (221) and / or second sub-region (231). A plastic container (100) according to any one of claims 1 to 6, characterized in that the first sub-region (221) and the second sub-region (231) are separated on the side of the filling volume facing away from the materially bonded connection, so that a through-opening (40) is formed. A plastic container (100) according to any one of claims 1 to 7, characterized in that it is formed from a polymer with a dipole, in particular PET. Method for producing a bead (31) of molten material between a first wall (22) and a second wall (23) opposite the first wall (22) of a container body (20), comprising the steps: - Providing a stretch-blown plastic container (100) with a container body (20) forming a filling volume - a materially bonded connection of a first partial area (221) of the first wall (22) of the container body (20) with a second partial area (231) of the second wall (23) to form a handle (21) formed on the container body (20), such that the filling volume extends circumferentially around this materially bonded connection, characterized in that the materially bonded connection is created by high-frequency welding or friction welding, wherein pressure is exerted on the weld zone (32) during the welding process 16, such that at least a portion of the melt generated during the welding process is forced out of the weld zone (32) to form the bead (31). Method according to claim 9, characterized in that the melt is forced in the direction of the filling volume. Method according to claim 9 or 10, characterized in that the melt is forced out of the weld zone (32) until a bead (31) forming from the melt connects the first wall (22) and the second wall (23) in a region where the first wall (22) and / or the second wall (23) has a curvature. Method according to one of claims 9 to 11, characterized in that the melt is pressed out of the welding zone (32) until a bead (31) forming from the melt connects the first wall (22) and the second wall (23) in an area in which the first wall (22) is spaced apart from the second wall (23).A method according to any one of claims 9 to 12, characterized in that the melt is forced out of the welding zone (32) until a bead (31) forming from the melt projects beyond the surfaces (222, 232) of the first wall (22) and the second wall (23) facing the filling volume. A method according to any one of claims 9 to 13, characterized in that, prior to the materially interlocking joining of the first partial region (221) with the second partial region (231), the first partial region (221) and the second partial region (231) are brought into contact with each other within a blow mold (102) by movable punches (104, 105). 17 Method according to one of claims 9 to 14, characterized in that after the material-bonding joining, the first partial area (221) and the second partial area (231) are separated on the side of the filling volume (F) facing away from the material-bonding joining, so that a through-opening (40) is formed.