Blow-molded and stretch-molded plastic container and method for its manufacture

Abstract

The invention relates to a blow-molded and stretch-molded plastic container (100) with a body (20) forming a filling volume (F) and a handle (21) formed on the body. To form the handle (21), a first subregion (221) of a first wall (22) of the body (20) is joined to a second subregion (231) of a second wall (23) of the body (20) located opposite the first wall (22). The filling volume (F) extends circumferentially around the joint. A bead (31) of molten material is disposed within the filling volume between the first wall (22) and the second wall (23).

Description

[0001] The present invention relates to a stretch-blown plastic container and a method for producing a bead of molten material according to the preamble of the independent claims.

[0002] A wide variety of plastic containers are known from the state of the art.

[0003] Various processes exist for manufacturing plastic containers, particularly plastic bottles, the application of which depends, among other things, on the type of plastic used. Most plastic containers are produced using a blow molding process, in which plastic containers, such as plastic bottles, are inflated into their final shape under pressure within a mold. Different blow molding techniques are distinguished, the most notable of which are extrusion blow molding, injection blow molding, and injection stretch blow molding. In extrusion blow molding, a single- or multi-layer plastic tube is hot extruded, inserted into a mold, and inflated into a plastic container via a mandrel inserted into a cavity of the mold. Injection blow molding is a combination of injection molding and blow molding.In this process, a preform is first produced in an injection mold. The preform is demolded from the mold, conditioned if necessary, and placed into the cavity of a blow mold, where it is then inflated under pressure to the shape defined 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 inflating of the preform can take place immediately after its production in the injection molding process. In alternative manufacturing processes, the further processing of the preforms can also be carried out separately from their production, either spatially and / or temporally. Finally, it should also be mentioned that the preforms can be produced using a flow molding process or an extrusion blow molding process.

[0004] Furthermore, plastic containers with an integrated handle have become known, and 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 fully gripped by the hand. A relatively simple solution for providing such handles is achieved by having a through-hole in the plastic container.

[0005] From WO 2017 / 211540 A1, a plastic container, in particular made of PET, is known which has a reach-through opening and a corresponding handle. The reach-through opening of the plastic container of WO 2017 / 211540 A1 is obtained by welding two wall parts together after stretch blow molding of the plastic container and then cutting out a corresponding area from the container, separated by the weld seam.

[0006] A comparable plastic container made of polypropylene is known from EP 1 835 461 A2. Document US 12 227 329 B2 discloses the preambles of claims 1 and 9.

[0007] Both plastic containers have a seam located in the opening. This seam could potentially create a weak point in the container, which can be particularly disadvantageous in mail order, where product handling is not fully controllable and the containers are repeatedly subjected to loads exceeding their permissible weight.

[0008] The object of the invention is therefore to overcome at least one or more disadvantages of the prior art. In particular, it aims to provide a plastic container that is stable and can withstand higher loads.

[0009] This problem is solved by the devices and methods defined in the independent claims. Further embodiments are described in the dependent claims.

[0010] An inventive device 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 section of a first wall of the container body is bonded to a second partial section of a second wall opposite the first wall, such that the filling volume extends around this bonded connection. In other words, a single, continuous filling volume is created within the container body.

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

[0012] The placement of a bead between the first and second walls reduces the stress concentration at the junction between the two 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 for an integral connection between the bead, the first wall and the second wall, and thus the weld seam.

[0014] The bead can connect the first wall and the second wall in an area where the first wall and / or the second wall has a curvature.

[0015] In areas where the walls have curves, they are particularly susceptible to peeling under external force.

[0016] By placing a ridge in this area, the corresponding effects can be reduced, resulting in overall greater stability of the plastic container.

[0017] The bead can connect the first wall and the second wall in an area where the first wall is spaced away from the second wall.

[0018] Even in areas where gaps or spaces form between the walls to be joined, the connection between these walls is more susceptible to external influences, especially to force. By providing a bead in the area of ​​a gap between the first and second walls, particularly in the area of ​​a gap, the susceptibility to container failure can be counteracted.

[0019] Preferably, the bead extends beyond the surfaces of the first wall and the second wall that are directed towards the filling volume.

[0020] Such an arrangement can completely prevent a depression or notch between the first wall and the second wall, and strengthen the connection between the first wall and the second wall in this area.

[0021] Preferably, the bead is formed circumferentially along the first sub-area and / or the second sub-area.

[0022] In other words, the bead forms a continuous, 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.

[0023] The first sub-area and the second sub-area can be separated on the side of the filling volume facing away from the material-bonded connection, so that a through-opening is formed.

[0024] The plastic container can be made from a polymer with a dipole, especially PET.

[0025] Such polymers are particularly well suited for high-frequency welding, as their molecules can be excited particularly well.

[0026] Another 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: Providing a stretch-blown plastic container with a container body forming a filling volume, joining a first part of the first wall of the container body with a second part of the second wall to form a handle on the container body, so that the filling volume extends around this joining connection.

[0027] The metallurgical bond is created by high-frequency welding or friction welding. During the welding process, pressure is applied to the weld zone, so that at least some of the molten metal generated during the welding process is forced out of the weld zone to form the bead.

[0028] High-frequency welding and friction welding are processes that melt the components to be joined in the area of ​​contact. The pressure exerted on the walls being joined forces the resulting molten metal from the interior or from the area between the first and second walls to the outside, creating a bead that forms an integral part of the weld and, together with the weld, exhibits a correspondingly high strength. Because it is a molten bead, it can also bond with areas of the first and second walls that do not precisely meet and / or cannot be directly accessed by the welding equipment.

[0029] Preferably, the melt is pushed in the direction of the filling volume.

[0030] Accordingly, the bulge also forms in the area of ​​the container that is directed towards the filling volume and in which the first wall and the second wall meet.

[0031] 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 facing away from the filling volume.

[0032] Preferably, the molten metal is forced out of the welding zone until a bead forming from the molten metal connects the first wall and the second wall in an area where the first wall and / or the second wall has a curvature.

[0033] This allows a bead to fill the gap between the first and second walls, thus reducing the notch effect. Consequently, peeling of the first wall from the second wall in the event of excessive force can be prevented for a longer period.

[0034] Preferably, the molten metal is forced out of the welding zone until a bead forming from the molten metal connects the first wall and the second wall in an area where the first wall is spaced apart from the second wall.

[0035] This also ensures that a gap between the first and second walls is filled with a bead, thus reducing the notch effect. This can prevent the first wall from peeling away from the second wall in the event of excessive force for a correspondingly longer period.

[0036] It may be provided that the molten metal is forced out of the welding zone until a bead forming from the molten metal protrudes above the surfaces of the first wall and the second wall facing the filling volume.

[0037] The surface of the first wall, the surface of the second wall, and a surface of the bead form a common surface that is, in particular, free of notches and / or depressions. Such a common surface is especially resistant to the application of force and can withstand peeling processes for a long time.

[0038] Before the first sub-area is joined to the second sub-area in a material-bonded manner, the first sub-area and the second sub-area can be brought into alignment with each other within a blow mold using movable stamps.

[0039] This makes it possible to define the later shape of the plastic container in many areas and to shape the sections of the first wall and the second wall to be joined in a way that is advantageous for the welding process.

[0040] After the first and second sub-areas have been joined together, the first and second sub-areas can be separated on the side of the filling volume facing away from the joining, so that a through-opening is formed.

[0041] This allows for the creation of a container that is visually appealing, has a pleasant feel, and features a handle that can be fully gripped by the user. This ensures a secure hold on the container.

[0042] The invention is explained below using schematic figures and an exemplary embodiment. These show: Figure 1: A perspective view of a plastic container; Figures 2A, 2B: A schematic view of a blow molding process; Figure 3: A sectional view through a plastic container; Figure 4: A sectional view through a plastic container; Figure 5: A detail view from the Figure 4 Figure 6: the detailed view from the Figure 5 Figure 7: the detailed view from the Figure 5 Figure 8: the detailed view from the Figure 5 .

[0043] Figure 1 Figure 1 shows a plastic container 100 comprising 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 enclose the container body 20.

[0044] The container handle 21 is arranged so that it can be completely gripped. For this purpose, a through-opening 40 is provided in the container body 20. A filling volume extends around the through-opening 40. This filling volume fills both the container body 20 and the handle 21. In other words, the interior of the handle 21 is connected to the filling volume.

[0045] The Figures 2A and 2B The figures schematically illustrate a blow molding process. A preform 101 is placed into a mold 102. The preform 101 is already tempered at this point. The mold 102 essentially has the later outer contour of the plastic container. As shown in the Figure 2B As can be seen, a pull-up bar 103 is inserted into the preform 101 and stretched accordingly to inflate the preform 101. Simultaneously, a hot blowing medium is blown into the preform 101 under overpressure, allowing it to conform to the inner surfaces of the blow mold 102.

[0046] The Figure 3 shows a cross-section along line AA of the Figure 2B , where 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 sub-region 221 which is shaped with respect to an envelope curve in the direction of the interior of the container body 20. The second wall 23 also has a sub-region 231 which is shaped with respect to an envelope curve in the direction of the interior of the container body 20. The contour of the cross-section, as shown in the Figure 3 As shown, this can be achieved by the blow mold 102 and the corresponding inflation. The sections 221 and 231 are spaced apart from each other so that the area of ​​the future handle, on the right in the present figure, can also be completely inflated. The walls 22 and 23 define a filling volume F.

[0047] The Figure 4 shows a cross-section analogous to the cross-section according to the Figure 3 . In the Figure 4 The figure shows that sections 221 and 231 are deformed by punches 104 and 105, bringing them into contact with each other. 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, thus preserving the remaining contour of the container body. The filling volume F remains within the handle 21 and the remaining container body 20.

[0048] The Figure 5 shows a detailed view X from the Figure 4This detailed view illustrates part of the first sub-area 221 and part of the second sub-area 231. Sub-areas 221 and 231 are joined together and prepared, in particular, for subsequent welding. Sub-areas 221 and 232 each transition into walls 22 and 23, respectively.

[0049] Sections 221 and 231 are joined together by high-frequency welding. Two electrodes, not shown in detail here, press sections 221 and 231 together, melting the intervening material. The area being pressed together is designated here as weld zone 32. This is an area directly exposed to the electrodes. The melting process creates a weld seam 30. The overlapping surfaces of sections 221 and 231 soften in the weld zone, forming a melt that creates a weld seam. The electrodes press sections 221 and 231 together under high pressure. In the illustration according to the Figure 5 On the right, the sub-areas 221 and 231, or the walls 22 and 23, each exhibit a curvature in the area where the handle 21 is located (see figure). Figure 4) widens. In the area of ​​this curvature, the surfaces 222 and 232 of the walls 22 and 23 begin to separate from each other, creating a gap.

[0050] The Figure 6 shows one of the Figure 5 A corresponding detailed view will be shown at a later stage of the process. The pressure exerted by the electrodes causes at least part of the molten metal to be removed from the weld seam 30, particularly from the weld zone 32 (see Figure 5 ), is forced outwards 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 allows a joining zone to be created 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 point of force application on the walls 22 or 23 is reduced. This allows the joint to withstand higher loads.

[0051] As in the Figure 6 As illustrated, the welding process can be continued even further. The bead 31 then fills a gap created by the curvature of the walls 22 and 23, which directly leads to a reduction of 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 thus connects the first wall 22 and the second wall 23 in an area where the first wall 22 and the second wall 23 exhibit a curvature. In this area, the first wall 22 is also spaced apart from the second wall 23. The bead 31 therefore connects the walls 22 and 23 in this area and bridges a gap between the first wall 22 and the second wall 23.

[0052] The Figure 7 shows one of the Figure 6A corresponding detailed view will be shown at a later point in the process, if it is continued further. Through further melting and the pressure of the electrodes on the sub-areas 221 and 231, the melt was extended to both sides of the original weld seam 30 (see [reference]). Figure 5 ) pressed. Due to the present arrangement of the walls 22 and 23 and the corresponding sub-areas 221 and 231, a large portion of the weld molten metal 30 has been forced towards the open side of the gap between the first wall 22 and the second wall 23, and thus towards the filling volume F. The bead 31 almost completely fills the gap between the first wall 22 and the second wall 23. The notch effect resulting from the present geometry is further reduced because the contact area and the depressions in the gap are reduced. The bead 31 almost completely fills the gap in the direction of the filling volume F.

[0053] The Figure 8 shows one of the Figure 7 A corresponding detailed view will be shown at a later point in the process, if it is continued further. Through further melting and the pressure of the electrodes on the sub-areas 221 and 231, the melt was extended to both sides of the original weld seam 30 (see [reference]). Figure 5 ) pushed out even further. The resulting bulge 31 protrudes beyond the surfaces 222 and 232 of the walls 22 and 23 which are directed towards the filling volume F, so that the walls 22 and 23 are reinforced in the area of ​​the gap and thus in the area of ​​their curvature.

[0054] All trainings of the weld seam 30 and the bead 31, as they belong to the Figures 6 to 8As described, the bead 31 reinforces the connection between walls 22 and 23, increasing the strength of the connection and, in particular, reducing its susceptibility to failure. Impacts to the plastic container can cause the pressure within the filling volume F to become relatively high. The reduced notch effect and the filling of the gap with the bead 31 can reduce the influence of such impacts on the weld seam 30, i.e., on the connection between the first wall 22 and the second wall 23.

[0055] It is understood that the bead 31 can be formed circumferentially around the sub-areas 231 and 221, thus sealing them off from the filling volume F. The associated weld seam 30 therefore forms a continuous, circumferential seal of the sub-areas 221 and 231 against the container body 20. The weld seam forms a material-bonded connection. The first sub-area 221 and the second sub-area 231 can be cut off on the side of the filling volume facing away from the material-bonded connection, so that a through-opening 40 is formed (see [reference]). Figure 1 ).

Claims

1. Stretch-blow-molded plastic container (100) having a container body (20), which forms a filling volume (F), and a handle (21), which is formed on the container body, wherein, in order to from the handle (21), a first sub-region (221) of a first wall (22) of the container body (20) is integrally connected to a second sub-region (231) of a second wall (23) of the container body (20) lying opposite the first wall (22), such that the filling volume (F) extends peripherally around this integral connection, characterized in that a bead (31) made of melted material is arranged within the filling volume (F) between the first wall (22) and the second wall (23).

2. Plastic container (100) according to claim 1, characterized in that the bead (31) is 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 any one of claims 1 to 3, 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) is spaced apart from the second wall (23).

5. Plastic container (100) according to any one of claims 1 to 4, characterized in that the bead (31) projects, toward the filling volume, beyond the surfaces (222, 232) of the first wall (22) and of the second wall (23) that face the filling volume.

6. Plastic container (100) according to any one of claims 1 to 5, characterized in that the bead (31) is formed peripherally along the first sub-region (221) and / or the second sub-region (231).

7. 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 severed on the side of the filling volume remote from the integral connection, so that a reach-through opening (40) is formed.

8. Plastic container (100) according to any one of claims 1 to 7, characterized in that the plastic container is formed of a polymer having a dipole, in particular PET.

9. Method for producing a bead (31) made of melted material between a first wall (22) and a second wall (23) of a container body (20), the second wall lying opposite the first wall (22), comprising the steps of: - providing a stretch-blow-molded plastic container (100) having a container body (20) which forms a filling volume, - integrally connecting a first sub-region (221) of the first wall (22) of the container body (20) to a second sub-region (231) of the second wall (23) to form a handle (21) formed on the container body (20), such that the filling volume extends peripherally around this integral connection, characterized in that the integral connection is created by high-frequency welding or friction welding, wherein pressure is exerted on the welding zone (32) during the welding process so that at least a portion of the melt produced during the welding process is pressed out of the welding zone (32) to form the bead (31).

10. Method according to claim 9, characterized in that the melt is pressed toward the filling volume.

11. Method according to claim 9 or 10, characterized in that the melt is pressed out of the welding zone (32) until a bead (31) formed from the melt 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.

12. Method according to any one of claims 9 to 11, characterized in that the melt is pressed out of the welding zone (32) until a bead (31) formed from the melt connects the first wall (22) and the second wall (23) in a region in which the first wall (22) is spaced apart from the second wall (23).

13. Method according to any one of claims 9 to 12, characterized in that the melt is pressed out of the welding zone (32) until a bead (31) formed from the melt projects, toward the filling volume, beyond the surfaces (222, 232) of the first wall (22) and of the second wall (23) that face the filling volume.

14. Method according to any one of claims 9 to 13, characterized in that, before the first sub-region (221) is integrally connected to the second sub-region (231), the first sub-region (221) and the second sub-region (231) are brought into contact with one another by means of movable dies (104, 105) within a blow mold (102).

15. Method according to any one of claims 9 to 14, characterized in that, after the integral connecting, the first sub-region (221) and the second sub-region (231) are severed on the side of the filling volume (F) remote from the integral connection, so that a reach-through opening (40) is formed.

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