Method for producing a closure cap for containers
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-27
- Publication Date
- 2026-03-04
Smart Images
Figure EP2024058178_31102024_PF_FP_ABST
Abstract
Description
[0001] Method for producing a closure cap for containers
[0002] The invention relates to a method for producing a closure cap for containers using an injection molding tool comprising at least one core tool and at least one jacket tool extending over the core tool, both of which are formed around a common central axis and, when the injection mold is closed, form a volume region between them that defines the closure cap and into which molten plastic is injected. The invention also relates to a closure cap produced in this way.
[0003] In the prior art and also in the invention, the injection molding tool is preferably closed by inserting at least one core tool into the shell tool in the direction of the common center axis until these two tools assume a predetermined desired axial distance from one another. In the prior art and also in the invention, the opening can preferably take place in the opposite direction in order to demold the produced closure cap, wherein it can be provided that the shell tool rotates about the common center axis, e.g. if a closure cap has been produced which has an internal thread and for this purpose the core tool has a corresponding thread or corresponding thread sections on its radially outward-facing shell surface.
[0004] Methods for producing container closure caps using the principle of plastic injection molding in an injection mold are generally known, for example, from publication EP 4144662 A1. The closure caps produced in this way can be used for a wide variety of containers. In the technical field of containers, e.g., made of glass or plastic, such as bottles or canisters, especially those intended for chemical substances, which is also the preferred area of application of the invention, the demands placed on the closure cap are high.
[0005] For example, the caps must seal the containers tightly, be sufficiently sturdy, especially so as not to break even if the container is dropped, and, on the one hand, they must protect the contents within the container from substances in the environment, while, on the other, they must also protect the environment from substances contained within the container. These requirements are often not met by conventional caps.
[0006] It is therefore an object of the invention to further develop a method for producing a closure cap of the type mentioned at the outset in such a way that a secure and stable closure cap is achieved with the method.
[0007] According to the invention, the object is achieved in that the core tool has an axial end face in which a recess surrounding the central axis is formed, and the jacket tool has a projection surrounding the central axis on its inner axial end face, wherein before the injection molding tool is closed, an insert element, preferably a flat insert element, preferably a circular disk-shaped insert element is positioned between the two opposite axial end faces, and upon closing of the injection molding tool, the projection penetrates at least partially into the recess and thereby deforms the insert element, and after closing of the injection molding tool, the volume area is filled with molten plastic through a sprue opening positioned in the projection, preferably on the central axis,whereby the insert element is pressed by the plastic from the direction of the shell tool against the axial end face of the core tool.
[0008] The closing of the injection molding tool is preferably carried out by a linear movement between the core tool and the outer tool, preferably without rotation of the two tools against each other, but rotation can also be provided during closing, e.g. in order to bring the two tools into a desired angular position relative to each other.
[0009] Preferably, the aforementioned recess is surrounded by an annular surface, preferably a partially flat annular surface. The recess can preferably have a bottom surface, in particular a flat bottom surface at least partially, which is offset from the annular surface in the axial direction by the depth of the recess. In this description of the invention, the axial direction is generally the direction of the common center axis or parallel thereto.
[0010] The axial, in particular inner, end face of the shell tool lies opposite the axial end face of the core tool in the closed state of the injection molding tool, forming a distance, wherein the previously not yet formed, preferably flat / level insert element lies in this distance area.
[0011] By means of the said forming, the insert element, preferably the initially flat insert element, is preformed in the direction of the final shape, in particular at least substantially pot-shaped or bowl-shaped, in particular preformed in the sense that the insert element approaches the final shape as a result of the forming, except for the play in the distance area between the two tools.
[0012] The procedure according to the invention ensures that the insert element is covered by plastic only on one side from the direction of the casing tool, but is exposed in the interior of the closure cap produced in this way, in particular with contact to the contents of a container which is to be closed with the closure cap.
[0013] The recess in the axial end face of the core tool is designed in such a way that a projection is formed in the produced cap, projecting inward from the cap lid and penetrating axially into the interior of the container neck when the container is closed with the cap. Such a projection can thus preferably form a plug arranged on the cap lid area, which also exerts a sealing function in the radial direction towards the inner wall area of the container neck. The seal is achieved via the insert element, which covers the plug thus formed. The annular surface of the end face of the core tool, mentioned above, forms a collar in the pot- or bowl-shaped insert element, in particular a radially outer collar, which covers the annular end face of the container neck when a container is closed.
[0014] The closure cap produced according to the invention thus has an extended sealing function compared to the prior art.
[0015] The projection in the shell tool is preferably further configured such that a recess is formed on the outside of the produced closure cap, preferably with the gate point located in the center of said recess. This gives the closure cap lid a shape that deviates from a purely flat form, in particular a pot- or bowl-shaped shape with a radially outer edge in the lid area that merges into the at least substantially axially extending shell surface of the closure cap. This design leads to increased stability of the closure cap, particularly in the lid area that covers the container neck opening, and thus also to improved sealing.
[0016] In a closure cap manufactured according to the invention, the insert element is preferably the only element of the closure cap that can come into contact with the contents of the container. The insert element can thus perform a sealing function on the one hand, but also form a diffusion barrier for the contents of the container, both against diffusion of the contents to the outside and against diffusion of ambient substances, e.g., oxygen, into the inside of the container. The closure cap according to the invention thus achieves several advantages through the combination of a formed insert element with a lid region shaped into an inner plug.
[0017] The invention can provide for the closure cap to always be produced by injection molding using the same plastic, e.g. polyethylene (PE) or polypropylene (PP), although the invention is not limited to these plastics.
[0018] Furthermore, it may be provided that, depending on the application of the closure cap to be produced, the material of the insert element that comes into contact with the container contents is selected depending on the intended container contents.
[0019] Preferably, the insert element is made of a fluoropolymer, in particular one of the following materials: perfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), polyvinylidene fluoride (PVDF), or polytetrafluoroethylene (PTFE). Such fluoropolymers have the advantage of being resistant to many chemicals and, in particular, of being poorly wetted by liquid chemicals, so that only minimal amounts of the container contents can remain inside the closure cap, especially on the insert element.
[0020] In general, the invention can provide that the insert element is selected from a material to which the plastic does not bond firmly during injection molding, in particular according to the invention the insert element is then held in the cap exclusively in a form-fitting and / or force-fitting manner.
[0021] Not only does the plastic adhere poorly to such materials, e.g. the previously mentioned fluoropolymers, but - as mentioned - the container contents then advantageously adhere just as poorly. However, the form-fitting hold ensures a permanent position of the insert element in the closure cap. Due to the deformation of the insert element and the contacting of the injected plastic, a form fit between the insert element and the injected solidified plastic is achieved in the inventive shaping both in axially and radially oriented surface areas of the lid area of the closure cap, in particular a form fit of the solidified injection plastic with one of the two surfaces of the insert element which are opposite one another across the thickness of the insert element and are preferably originally flat and deformed according to the invention.Further preferably, a positive connection is also achieved between the radially outer edge surface of the originally non-formed insert element, preferably a flat insert element, and the solidified injection plastic, in particular by which peeling off of the insert element from the solidified injection plastic near the edge is prevented.
[0022] The invention can preferably provide that in one possible embodiment the circular disk diameter of the insert element is selected, in particular selected to be larger or smaller than the outer diameter of the axial end face, in particular than the outer diameter of the annular surface surrounding the recess, preferably a partially planar annular surface of the axial end face of the core tool, such that when the projection penetrates into the recess and / or by being pressed against it with the plastic, the radially outwardly facing edge surface of the insert element comes to lie on the axial end face, in particular on the annular surface surrounding the recess, preferably a partially planar annular surface of the axial end face.
[0023] In this embodiment, the insert element is preferably located exclusively axially in front of the axial end face of the core tool after the forming process, without encompassing its outer surface.
[0024] In another embodiment, the invention preferably provides that the circular disc diameter of the insert element is selected to be larger than the outer diameter of the axial end face, in particular than the outer diameter of the annular surface surrounding the recess, preferably a partially planar annular surface of the axial end face of the core tool, and that the core tool has an annular surface in its outer surface, over which the outer surface tapers in cross-section, in particular in the outer diameter, in the direction of the axial end face, wherein by closing the injection mold and / or by pressing with the plastic, a radially outer edge region of the insert element is folded over in the axial direction onto the outer surface, preferably wherein the radially outwardly facing edge surface of the originally non-formed,preferably flat insert element in the folded state contacts in the axial direction a radially inwardly projecting annular projection in the cap, which is formed by the plastic molded onto the annular surface.
[0025] Preferably, the annular surface in the core tool is formed axially above the last thread pitch. The annular surface can preferably form a step at which the tapering of the lateral surface occurs. The annular surface can be flat, at least in part or entirely, but preferably the annular surface is concave radially outward, in particular rounded. In this embodiment, the lateral surface of the core tool is therefore covered by the insert element in the axial end region of the core tool.
[0026] In a further preferred embodiment, which can be combined with all embodiments of the invention, it is provided that the axial inner end face of the casing tool has radially extending grooves, in particular the radial inner circumferential surface of the casing tool also has axially extending grooves, preferably with the grooves of the axial end face and the circumferential surface merging into one another, with reinforcing ribs being formed by the grooves in the lid area and / or in the circumferential area of the closure cap during injection molding. This also further improves the stability of the closure cap in the lid area.In the invention, it is preferably further provided that, before the injection molding tool is closed, a two-part tamper-evident ring is arranged between the core element and the casing element, which is connected by injection molding to the lower edge region surrounding the closure cap opening radially inside the closure cap, in particular at least in a form-fitting and force-fitting manner, preferably also in a material-fitting manner.
[0027] Such a ring is provided, for example, to indicate the first opening of a container sealed with the closure cap according to the invention. It is preferably provided that a part of the two-part tamper-evident ring attached to the closure cap remains in the closure cap during opening, while another part remains attached around the container neck.
[0028] Preferably, the method provides that the core tool comprises a core inner part which is coaxially surrounded by a first core sleeve, which is coaxially surrounded by a second core sleeve, wherein an annular gap which is open in the axial direction is formed between the core sleeves, in particular in the region of their respective axial ends, into which an annular gap the tamper-evident ring is inserted with at least an axially extending partial region.
[0029] The tamper-evident ring preferably comprises a first division and a second division, which are spaced apart in the axial direction by a gap and are connected in the axial direction by axially extending breakable bridges in a gap-bridging manner, wherein the division pointing in the axial direction to the axial end face of the jacket tool closes the annular gap between the core sleeves against the penetration of liquid plastic and is connected to the injected plastic with its surface pointing into the volume area of the injection mold.
[0030] The gap between the divisions and any openings or projections, especially the shape previously formed in the other division, thus remains shielded and unaffected by the injected plastic. These breakable bridges allow the tamper-evident ring to be broken into its two partial rings during the opening process of a container, leaving one (lower) division around the container neck and one (upper) division in the closure cap.
[0031] The tamper-evident ring itself can preferably be produced in a prior injection-molding step, in particular from the same material from which the closure cap is formed.
[0032] For example, in the preceding injection molding step, radially inwardly extending projections and radially extending openings can preferably be molded into the plastic-shielded division of the tamper-evident ring, in particular by means of an injection molding tool which comprises a multi-part shell tool whose parts are movable in the radial direction.
[0033] Embodiments of the invention are explained in more detail with reference to the figures.
[0034] Figure 1 shows a sectional view of a perspectively visualized arrangement of all essential components for carrying out the method for producing a closure cap, which is shown in section in Figure 6.
[0035] The injection molding tool 2 comprises a core tool 2a, which has an inner core part 2a1, a first core sleeve 2a2 arranged coaxially therearound, and a second core sleeve 2a3 arranged therearound. Preferably, the core sleeves 2a2 and 2a3 are axially displaceable relative to the inner core part 2a1, parallel to the common center axis 3.
[0036] An axially displaceable ejector sleeve 2a4 can additionally be arranged coaxially around the outside of the second core sleeve 2a3, e.g. in order to strip the closure cap produced later from the second core sleeve 2a3.
[0037] Between the core sleeves 2a2 and 2a3 there is an annular gap 17 which is open in the axial direction to the casing tool 2b and into which a tamper-evident ring 16 can be inserted, which is formed in two parts in the axial direction from an upper part 16a and a lower part 16b.
[0038] As Figure 2 shows, the lower division 16b preferably immerses completely into the annular gap 17, with the upper division 16a closing the axially open side of the annular gap 17.
[0039] In the open state of the injection molding tool 2, an insert element 10, here preferably a flat insert element 10 made of, for example, a fluoropolymer, is inserted axially between the axial end face 6 of the core tool 2a and the axial end face 8 of the shell tool 2b. Figure 2 shows that the insert element 10 rests on the annular surface 6a of the axial end face 6, which surrounds a recess 7 in the axial end face 6. In this case, the recess 7 is covered by the insert element 10. Preferably, in the embodiment shown, the outer diameter of the insert element 10 is larger than the outer diameter of the axial end face 6 and / or than the outer diameter of the annular surface 6a. However, the outer diameter of the insert element 10 can also be smaller than the outer diameter of the axial end face 6 and / or than the outer diameter of the annular surface 6a.
[0040] Figure 3 shows the arrangement of the elements of Figure 1 in a closed state of the injection molding tool 1. Here, the core tool 2a comprising the core inner part 2a1, the core sleeves 2a2, 2a3 and ejector sleeve 2a4 as well as the jacket tool 2b enclose a volume area 4 into which the closure cap 1 is formed by injection of liquid plastic.
[0041] Figure 3 further shows that, upon closing the injection mold 2, the originally unformed, preferably flat insert element 10 is pre-formed by the projection 9 at least partially dipping into the recess 7, thereby contacting and carrying the insert element 10. This is similar to a deformation of the insert element 10 by deep drawing. Preferably, the insert element can assume any desired shape within the gap formed between the axial end faces 6 and 8.
[0042] Figure 4A shows an embodiment of the core tool 2a in which the annular surface 6a of the axial end face 6 is partially planar and merges into the recess radially inward and into the lateral surface of the core tool radially outward, preferably in each case rounded.
[0043] Axially spaced from the annular surface 6, an annular surface 12 is located in the lateral surface, where the lateral surface tapers in diameter toward the annular end face 6a or the axial end face 6. Here, the annular surface 12 is rounded and thus forms a step that is concave radially outward. Other shapes of the annular surface 12 are also possible, e.g., flat or convex toward the outside.
[0044] Figure 4B shows the arrangement of the formed insert element 10, pressed onto the core tool 2a by plastic, without visualizing the plastic. It is clear here that plastic molded onto the annular surface 12 can form an annular projection 13 in the closure cap, to which the edge 10b of the radially outer region 10a of the insert element, which faces radially outward in the unformed state and is folded over onto the outer surface after forming, adjoins in a form-fitting manner in the axial direction. Figure 7 shows this annular projection 13 on the finished cap.
[0045] Figure 5 visualizes the actual injection molding process, in which liquid plastic 5, e.g. polyethylene or polypropylene, is injected through the sprue 11 into the volume region 4. The plastic 5 presses the insert element 10 from the side of the jacket tool 2b against the end face 6 of the core tool 2a, or against the surface of the recess 7 and the annular surface 6a, wherein the plastic 5, starting at the sprue 11, fills the volume 4, initially radially outwards and then in the axial direction towards the tamper-evident ring 16. The injected plastic can bond, preferably in a material-to-material manner, to the surface of the upper partial ring 16a of the tamper-evident ring 16 facing into the volume region 4.
[0046] It can be provided, however, that the plastic 5 does not bond to the contacted surface of the insert element 10 in a material-locking manner, but only in a form-fitting and / or force-fitting manner, in particular if a fluoropolymer was selected as the material of the insert element.
[0047] If the outer diameter of the insert element 10 is larger than the outer diameter of the axial end face 6, or larger than the diameter of its annular surface 6a, then the radially outer edge region 10a is folded over in the axial direction onto the outer surface of the core tool 2a as shown in Figures 4 and 7.
[0048] In this embodiment, it can preferably be provided that an annular surface 12 is arranged in the outer surface of the core tool 2a, in particular of the inner core part, preferably above the last thread, wherein the molding of plastic onto the surface of the annular surface 12 leads to the formation of the annular projection 13, which is contacted in the axial direction by the edge surface 10a of the insert element 10. Overall, due to the embodiment according to the invention, the insert element 10 is held in a form-fitting manner by injected plastic in radial and axial surface areas, so that the insert element 10 is securely fixed in the closure cap 1 even without a material bond to the injection plastic.
[0049] Figure 5 shows an embodiment in which the outer diameter of the insert element 10 after forming and pressing by plastic is smaller than the outer diameter of the annular surface 6a or than the outer diameter of the axial end face 6, so that the insert element 10 rests on the annular surface 6a and does not cover the outer surface.
[0050] Figure 7 further shows the formation of reinforcing ribs 15, which run in the radial direction on the lid area and in the axial direction on the jacket area of the closure cap 1 and are formed by corresponding grooves 14 in the inner surface of the jacket tool.
[0051] Figure 6 further visualizes the preferably material-locking connection of the tamper-evident ring 16 with its upper division 16a in the lower open edge region of the closure cap, in particular in a region of the closure cap 1 where the cap jacket widens radially outwards.
[0052] The upper partial ring 16a is spaced apart from the lower division 16b, forming a gap 16c, but is connected to it via axially extending breakable bridges 16. Furthermore, the lower division 16b includes radially inwardly projecting projections 16e, which can engage behind an annular projection on the container neck, and radially extending openings 16f.
[0053] The tamper-evident ring can be manufactured using an injection molding tool according to Figure 9, which comprises radially movable shell tools 18 with radial pins to form the openings 16f.
[0054] Figure 6 also shows the recess formed in the lid area of the closure cap 1, which contributes to the stability of the cap and which is created by the projection on the inside of the casing tool.
[0055] After injection molding according to Figure 5, the unit consisting of the core inner part 2a1 and the first core sleeve 2a2 can be removed from the closure cap 1 by rotation according to the thread configuration created during injection molding. The closure cap can be pushed away from the second core sleeve using the stripper sleeve 2a4. The closure cap can be easily removed from the shell tool 2b.
Claims
Patent claims 1. A method for producing a closure cap (1) for containers using an injection molding tool (2) which comprises at least one core tool (2a) and at least one jacket tool (2b) which overlaps the core tool (2a), both of which are formed around a common central axis (3) and which, when the injection molding tool (2) is closed, form between them a volume region (4) which defines the closure cap (1) and into which molten plastic (5) is injected, characterized in that a. the core tool (2a) has an axial end face (6) in which a recess (7) surrounding the central axis (3) is formed, and b. the jacket tool (2b) has, on its inner axial end face (8), a projection (9) surrounding the central axis (3), c.wherein, before the injection molding tool (2) is closed, an insert element (10), preferably a flat insert element (10), preferably a circular disk-shaped insert element (10), is positioned between the two opposite axial end faces (6, 8), and d. when the injection molding tool (2) is closed, the projection (9) penetrates at least partially into the recess (6) and in the process deforms the insert element (10), and e. after the injection molding tool (2) is closed, the volume region (4) is filled with molten plastic (5) through a sprue opening (11) positioned in the projection (9), preferably on the central axis (3), whereby the insert element (10) is pushed through the plastic (5) from the direction of the casing tool (2b). is pressed against the axial end face (6) of the core tool (2a).
2. Method according to claim 1, characterized in that a. the circular disc diameter of the insert element (10) is selected, in particular larger or smaller than the outer diameter of the axial end face, in particular as the outer diameter of the annular surface surrounding the recess (7), preferably the partially planar annular surface (6a) of the axial end face (6) of the core tool (2a), such that upon penetration of the projection (9) into the recess (7) and / or by pressing with the plastic, the radially outwardly facing edge surface (10b) of the insert element comes to rest on the axial end face, in particular on the annular surface surrounding the recess (7), preferably the partially planar annular surface (6a) of the axial end face (6), or b. the circular disc diameter of the insert element (10) is selected larger than the outer diameter of the axial end face (6),in particular as the outer diameter of the annular surface (6a) surrounding the recess (7), preferably a partially planar annular surface (6a) of the axial end face (6) of the core tool (2a), and the core tool (2a) has an annular surface (12) in its lateral surface, over which the lateral surface tapers in cross-section, in particular in diameter, in the direction of the axial end face (6), wherein by closing the injection molding tool (2) and / or by pressing with the plastic (5), a radially outer edge region (10a) of the insert element (10) is folded over in the axial direction onto the lateral surface, preferably wherein the radially outwardly facing edge surface (10b) of the originally unformed, preferably originally planar insert element (10) in the folded state contacts in the axial direction an annular projection (13) projecting radially inwards in the closure cap (1),which is formed by the plastic (5) molded onto the ring surface (12).
3. Method according to one of the preceding claims, characterized in that the insert element (10) is selected from a material to which the plastic (5) does not bond firmly during injection molding, in particular as a result of which the insert element (10) is held in the closure cap (1) exclusively in a form-fitting and / or force-fitting manner.
4. Method according to one of the preceding claims, characterized in that the insert element (10) is selected from a fluoropolymer, in particular from one of the following materials: perfluoroalkoxy (PFA), ethylene-tetrafluoroethylene (ETFE), ethylene-chlorotrifluoroethylene (ECTFE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), in particular wherein the plastic (5) used for injection molding is selected from polyethylene (PE) or polypropylene (PP).
5. Method according to one of the preceding claims, characterized in that the axial end face (8) of the casing tool (2b) has radially extending grooves (14), in particular the radial casing surface of the casing tool (2b) also has axially extending grooves (14), preferably wherein the grooves (14) of the axial end face (8) and the casing surface merge into one another, wherein reinforcing ribs (15) are formed by the injection molding through the grooves (14) in the cover region and / or in the casing region of the closure cap (1).
6. Method according to one of the preceding claims, characterized in that before closing the injection mold (2) a two-part tamper-evident ring (16) in the axial direction is arranged between the core element (2a) and the casing element (2b), which is connected by injection molding at the lower edge region surrounding the closure cap opening radially inward to the closure cap (1), in particular at least positively and non-positively, preferably also materially.
7. Method according to claim 6, characterized in that the core tool (2a) comprises a core inner part (2a1) which is coaxially surrounded by a first core sleeve (2a2) which is coaxially surrounded by a second core sleeve (2a3), wherein between the core sleeves (2a2, 2a3) a An annular gap (17) is formed which is open in the direction and into which the tamper-evident ring (16) is inserted with at least an axially extending partial area.
8. The method according to claim 6 or 7, characterized in that the tamper-evident ring (16) comprises a first division (16a) and a second division (16b) which are spaced apart in the axial direction by a gap (16c) and are connected in the axial direction by axially extending breakable bridges (16d) to bridge the gap, wherein the division (16a) pointing in the axial direction towards the axial end face of the casing tool (2b) closes the annular gap (17) between the core sleeves (2a2, 2a3) against the penetration of liquid plastic (5) and is bonded to the injected plastic (5) with its surface pointing into the volume region (4) of the injection molding tool (2).
9. Method according to one of the preceding claims 6 to 8, characterized in that the tamper-evident ring (16) is produced in a preceding injection-molding step, in particular from the same material (5) from which the closure cap (1) is formed.
10. The method according to claim 9, characterized in that in the partition (16b) shielded by plastic (5), radially inwardly extending projections (16e) and / or radially extending openings (16f) are formed in the preceding injection molding step, in particular by means of an injection molding tool which comprises a multi-part casing tool (18), the parts (18a, 18b) of which are movable in the radial direction.
11. Closure cap (1) for containers produced according to a method according to one of the preceding claims 1 to 10.