METHOD AND INJECTION MOLDING TOOL FOR PRODUCE A PRODUCT FROM INSERT AND INJECTED PLASTIC BODY

Description

Technical area

[0001] The invention relates to a method and an injection molding tool for producing a product comprising an insert with an edge to be reinforced and a plastic body molded onto the edge, wherein the plastic body surrounds an edge region of the insert on both sides and on the front side. Technical background

[0002] Especially in containers and packaging, there is a need to provide flat, flexible parts along one edge with a plastic body that has a higher strength than the flat material.

[0003] In most cases, the individual parts are manufactured separately and then mechanically assembled and, if necessary, glued together (e.g. FR2175094 or EP0453754).

[0004] US2009250372 discloses a container formed from a blank and forming a flange. A bottom surface of the flange is provided with an injection-molded structure.

[0005] WO2015000797 discloses a more efficient method for molding a plastic collar directly onto the peripheral edge of an insert. For this purpose, the insert is inserted into a receiving cavity of an injection mold. The edge region of the insert to be molded over is fixed in the injection mold by means of stationary and movable tool parts. The receiving cavity extends only over a few partial areas on the underside of the edge region. In a first step, radially outwardly directed plastic webs are molded onto the underside of the edge region. In a second step, tool parts, between which the plastic webs have been formed, are lowered, and a peripheral collar is formed on the underside of the edge region in a second injection.Subsequently, a movable cavity-forming tool part is moved away from the top of the edge area and the released cavity is filled in a third injection to form the circumferential collar on the top.

[0006] The main problem with overmolding the edge area is that the materials to be overmolded are often not dimensionally stable or cannot withstand the pressure generated during the injection process and are forced away uncontrollably by the melt. For this reason, the process described in WO2015000797 is based on a complex injection molding tool with a multitude of independently movable, cavity-forming tool parts. These first fix the edge area and gradually release partial areas of a cavity until the edge of the insert is completely overmolded. This means that at the end of the injection molding process, the edge area is enclosed by the plastic body on both sides and across the end face. Description of the invention

[0007] It is an object of the invention to provide a method for producing a product from an insert and an injection-molded plastic body, which solves the problems of the prior art and ensures a reliable, firm connection between an insert and an injection-molded plastic body.

[0008] This object is achieved by a method having the features of claim 1 and an injection molding tool having the features of claim 8.

[0009] The method for producing a product comprising a cup-shaped insert with a circumferential edge to be reinforced and a circumferential plastic body molded onto the edge, wherein the plastic body surrounds an edge region of the cup-shaped insert on both sides and at the front, comprises the following steps: (a) providing a first mold section of an injection molding tool; (b) inserting the cup-shaped insert into the first mold section, wherein the first mold section and the insert are designed such that a first circumferential cavity is formed on the inside and at the front of the edge region to be molded over, and the insert rests with the outside of the edge region against a wall of the first cavity;(c) Injecting a first plastic melt into the first circumferential cavity to produce a first circumferential plastic body part, wherein the circumferential cavity has a web which forms a recess in the first circumferential plastic body part on the end face of the edge region of the insert part; (d) Providing a second mold section of an injection molding tool; (e) Inserting the cup-shaped insert part with the first circumferential plastic body part into the second mold section, wherein the second mold section is designed such that a second circumferential cavity for producing a second circumferential plastic body part is formed on the outside of the edge region to be overmolded and that the recess in the first circumferential plastic body part is connected to the second circumferential cavity;(f) injecting a second plastic melt into the second mold section so that the second plastic melt flows through the recess of the first plastic body part, fills the second cavity, and thus forms the second plastic body part; (g) demolding the product with a surrounding plastic body consisting of the first and second plastic body parts;

[0010] The process involves producing the plastic body using a two-component injection molding process, in which a first, circumferential plastic body part is first molded, followed by a second, circumferential plastic body part. The two parts are firmly bonded together at the end face of the edge area of ​​the insert, thus forming the circumferential plastic body.

[0011] The advantage of the process is that the web creates a passage in the first circumferential plastic body part through which the second plastic melt flows into the second cavity. This allows the injection points or injection molding nozzles to be arranged on the same side of the cup-shaped product—namely, on the side facing away from the bottom. This is particularly advantageous because there is hardly any space for the injection molding nozzles on the side facing the bottom.

[0012] A mold section typically comprises a die and a core, which together form the cavity of an injection mold. A cup-shaped insert typically has a base and a circumferential side wall. "Inside" refers to the inside of the cup-shaped insert. If the cup-shaped insert has an outward-facing flange (i.e., a flange-like outward-facing edge) on the upper open edge, e.g., for attaching a cover film and / or for forming sealants, "inside" also refers to the upper side of the flange facing away from the base of the cup-shaped insert. The term "front side" refers to the front side of the edge or flange, respectively. The term "outside" refers to the outside of the cup-shaped insert. If a flange is present, this also refers to the lower side of the flange facing the base.

[0013] The edge to be reinforced refers to a region of the insert that is narrow and extends over a certain length (e.g., an elongated edge of an insert). The edge region has two opposing side surfaces and an end surface. Such an edge region often exhibits insufficient stability, and it is desirable to reinforce it, for example, to give the finished product more stability or to provide other functions (e.g., attachment areas for additional parts such as lids, etc.). The edge region can, for example, be the upper, circumferential edge of a cup or the body of a coffee capsule.

[0014] The process is suitable for inserts with a flexible edge area that is at risk of being pushed away by the plastic melt, preventing a firm and permanent bond with the plastic body. Accordingly, the insert can be thin-walled and / or flat.

[0015] Plastic refers to all injection-moldable materials. This includes conventional injection-moldable plastics, but also innovative injection-moldable materials made from natural substances that may no longer be referred to as plastics in the future.

[0016] In some embodiments, the first and second mold sections, or the first and second cavities, can each have at least one injection point for the first and second plastic melts, respectively. The web can be arranged in a region in which two flow fronts of the first plastic melt meet. If, for example, a single injection point is present, the web is preferably located on the opposite side of the circumferential cavity, specifically in the region in which the flow fronts of the first plastic melt meet. If multiple injection points are present, the cavity can preferably also have multiple webs. The multiple injection points can be arranged evenly along the first cavity, and the multiple webs can each be arranged centrally between two injection points. Here, too, the webs are then located in the region in which the flow fronts of the first plastic melt meet.

[0017] In some embodiments, the insert with the first plastic body part can be inserted into the second mold section such that the recess is located at the injection point for the second plastic melt. This recess thus forms part of the second cavity into which the second plastic melt is injected. The recess allows the injection molding nozzle for the second plastic melt to be arranged on the same side as the injection molding nozzle for the first plastic melt.

[0018] In some embodiments, the injection point for the first plastic melt and the injection point for the second plastic melt may be located on the same side of the respective mold section.

[0019] The product can be a container with a container body or a container wall and a collar surrounding a container opening, wherein the container body or the container wall is formed by the insert and the container collar is formed by the plastic body. The surrounding collar can have a flange-like outward-facing edge, an external thread, or locking means for a container lid. The container lid can accordingly be a sealing film, a screw lid, or a container lid with opposing locking means.

[0020] The insert can have a circular, oval, or rectangular peripheral edge. A rectangular peripheral edge typically has rounded corners. The insert can also have a flange-like, outward-facing edge (flange), which is overmolded with the plastic body.

[0021] The insert may have a flexible, non-dimensionally stable and / or thin-walled or flat edge region. It may be made of paper, cardboard, a textile fabric, metal, plastic, or laminates of such materials. Some of the materials may be biodegradable or compostable (industrially and in home compost). The thickness of the edge region can be 0.1 to 2 mm. The edge region can be a circumferential edge region, e.g., the rim of a cup-shaped container. The edge region of the insert may have a rough surface or a coating so that the molded-on plastic can form a firm bond with the insert. The edge region can also be provided with recesses or openings for this purpose.

[0022] The molded plastic body can be designed, depending on its shape or material, to be stronger or more dimensionally stable than the edge area of ​​the insert, forming a stiffening plastic element. Biodegradable or compostable (industrially and in home compost) injection-moldable materials can also be used as plastic. In this context, the term "plastic" generally refers to all known and future injection-moldable materials.

[0023] The method can be used, for example, to produce a container comprising a container body having an upper, circumferential edge for forming an opening, and a circumferential plastic collar surrounding the upper edge. The container body can have a lower rigidity than the circumferential collar.

[0024] The invention further relates to an injection molding tool for carrying out the method for producing a product comprising an insert with an edge to be reinforced and a plastic body molded onto the edge, wherein the plastic body surrounds an edge region of the insert on both sides and at the end face. The injection molding tool comprises at least a first mold section and at least one second mold section. The first mold section forms a first circumferential cavity into which the insert with the edge region to be molded can be inserted, such that the outer side of the edge region rests against a wall of the first cavity. The first circumferential cavity has a web for creating a recess in the first circumferential plastic body part.The second mold section is designed such that the cup-shaped insert with the first circumferential plastic body part can be inserted into the second mold section and that a second circumferential cavity for producing the second circumferential plastic body part is formed on the outside of the edge region to be overmolded, wherein the recess in the first circumferential plastic body part is connected to the second circumferential cavity.

[0025] In some embodiments of the injection molding tool, the web can be arranged in a region in which two flow fronts of the first plastic melt meet.

[0026] In some embodiments of the injection molding tool, the first cavity may have a plurality of injection points and a plurality of webs, wherein the plurality of injection points are arranged uniformly along the first cavity and the plurality of webs are each arranged centrally between two injection points.

[0027] In some embodiments of the injection molding tool, the injection point for the first plastic melt and the injection point for the second plastic melt can be located on the same side of the respective mold section. Short explanation of the figures

[0028] The invention will be explained in more detail below using exemplary embodiments in conjunction with the drawing(s). They show: Fig. 1 shows a sectional view of a first mold section at (a) in the area of ​​an injection point and at (b) in the area of ​​a web; Fig. 2 shows a sectional view of a second mold section at (a) in the area of ​​the injection of the first injection-molded body part and at (b) in the area of ​​an injection point; Fig. 3 shows a sectional view through a section of a product comprising an insert and an injection-molded plastic body; Fig. 4 shows a sectional view through the first mold section in the area of ​​the first cavity. Ways to implement the invention

[0029] Fig. 4 shows a sectional view through a section of a product consisting of a cup-shaped insert 3 with a circumferential edge to be reinforced and a circumferential plastic body 4 injection-molded onto the edge. The plastic body 4 encloses an edge region 31 of the cup-shaped insert 3 on both sides and at the front. The cup-shaped insert 3 typically has a base and a circumferential side wall. A flange-like, outward-facing edge (flange) is formed on the upper edge of the side wall. The plastic body 4 is injection-molded in a two-component process using two mold sections, as explained further below, and is accordingly made from a first circumferential plastic body part 41 and a second circumferential plastic body part 42.

[0030] Fig. 1shows a sectional view of a section of a first mold section 1, below (a) in the area of ​​an injection point 12 for the first plastic melt and below (b) in the area of ​​a web 13. The first mold section 1 forms a first circumferential cavity 11, into which the edge region 31 of the insert 3 to be overmolded can be inserted. The outer side A of the insert 3 rests on a wall of the first cavity 11. The inner side I of the insert 3 is oriented towards the first cavity 11.

[0031] The cavity 1 has at least one injection point 12 for the first plastic melt for producing the first circumferential plastic body part 41. This first circumferential plastic body part 41 forms part of the plastic body and is arranged on the inner side I of the insert. When the first plastic melt is injected, it is distributed in the first circumferential cavity 11. In a region of the first circumferential cavity 11, in which the flow fronts of the first plastic melt meet, a web 13 is formed within the first cavity 11 (cf. Fig. 1(b) ). This web 13 is arranged such that an end face S of the edge region 31 of the insert adjoins the web 13. The web 13 forms a recess 43 in the first plastic body part 41, the function of which is explained below under Fig. 2(b) is explained.

[0032] Fig. 2shows a sectional view of a section of a second mold section 2, under (a) in the region of the injection of the first injection-molded body part 41 and under (b) in the region of an injection point of a second circumferential cavity 21. The second mold section 2 forms the second circumferential cavity 21 for producing the second circumferential plastic body part 42. The second cavity 21 is designed such that the insert part 3 with the injection-molded first plastic body part 41 can be received therein and the free second cavity 21 is formed on the outside. The insert part with the first plastic body part 41 are aligned such that an injection point 22 of the second mold section 2 comes to lie in the recess 43 of the first plastic body part 41. The second plastic melt is injected through the recess 43 and thus fills the second cavity 21 on the outside A of the insert 3.

[0033] Fig. 4shows a sectional view through the first mold section 1 in the region of the first cavity 11. In the embodiment shown, the first mold section 1 is provided with two injection points 12, 12', which are arranged at diametrically opposite locations. Furthermore, the first cavity 11 has two webs 13, 13', each of which is arranged between the two injection points 12, 12' and each forms a recess 43 in the first plastic body part 41. The dashed line indicates the end face of the insert 3. List of designations

[0034] 1First mold section 11First circumferential cavity 12, 12'Injection point for the first plastic melt 13, 13'Web 2Second mold section 21Second circumferential cavity 22Injection point for the second plastic melt 3Cup-shaped insert 31Edge, edge area 4Plastic body 41First circumferential plastic body part 42Second circumferential plastic body part 43Recess AOutside of the edge area IInside of the edge area SSEnd face / end surface of the edge area

Claims

1. A method for the manufacture of a product comprising a cup-shaped insert part (3) with a circumferential rim to be reinforced and a circumferential plastic body (4) moulded onto the rim, wherein the plastic body (4) encloses an edge area (31) of the cup-shaped insert part (3) on both sides and on the front side, wherein the method comprises the following steps: a. providing a first mould section (1) of an injection moulding tool; b. inserting the cup-shaped insert part (3) into the first mould section (1), wherein the first moulded section (1) and the insert part (3) are designed such that a first circumferential cavity (11) is formed on the inside and front side of the edge area (31) and the insert part (3) rests with the outside of the edge area (31) against a wall of the first cavity (11); c. injection a first plastic melt into the first circumferential cavity (11) for the production of a first circumferential plastic body part (41), wherein the first circumferential cavity (11) has a web (13), which forms a recess (43) in the first circumferential plastic body part (41) at the front of the edge area of the insert part (4); d. providing a second mould section (2) of an injection moulding tool; e. inserting the cup-shaped insert part (3) with the first circumferential plastic body part (41) into the second mould section (2), wherein the second mould section (2) is designed in such a way that a second circumferential cavity (21) is formed on the outside of the edge area (31) to be over-moulded for the production of a second circumferential plastic body part (42) and that the recess (43) in the first circumferential plastic body part (41) is connected to the second circumferential cavity (21); f. injecting a second plastic melt into the second mould section (2) so that the second plastic melt flows through the recess (43) of the first plastic body part (41), fills the second cavity (21) and thus forms the second plastic body part (42); g. demoulding the product with a circumferential plastic body (4) consisting of the first and second plastic body parts (41, 42).

2. The method according to claim 1, characterized in that the first and second cavities (11, 21) each have at least one injection points (12, 12', 22) for the first and second plastic melts, respectively.

3. The method according to any one of the preceding claims, characterized in that the web (13) is arranged in a region in which two flow fronts of the first plastic melt meet.

4. The method according to any one of the preceding claims, characterized in that the first cavity (1) has several injection points (12, 12') and several webs (13, 13'), wherein the several injection points (12, 12') are uniformly arranged along the first cavity (11) and the several webs (13, 13') are each centrally arranged between two injection points (12, 12').

5. The method according to any one of the preceding claims, characterized in that the insert part (3) with the first plastic body part (41) is inserted into the second mould section (2) in such a way that the recess (43) is located at the injection point (22) for the second plastic melt.

6. The method according to any of the preceding claims, characterized in that the injection point (12, 12') for the first plastic melt and the injection point (22) for the second plastic melt are located on the same side of the respective mould section (1, 2).

7. The method according to any one of the preceding claims, characterised in that the product is a container, wherein the insert part (3) forms a container body or a container wall and the plastic body (4) forms a circumferential collar with a flange-like outward-facing edge, an external thread or latching means for a container lid.

8. An injection mould for carrying out the process according to any of the preceding claims, wherein the injection mould comprises at least a first mould section (1) and at least a second mould section (2), wherein the first mould section (1) forms a first circumferential cavity (11) into which the insert part (3) with the edge area (31) to be over-moulded can be inserted, so that the outside of the edge area (31) rests against a wall of the first cavity (11); wherein the first circumferential cavity (11) has a web (13) to create a recess in the first circumferential plastic body part; characterized in that the second mould section (2) is designed in such a way that the cup-shaped insert part (3) with the first circumferential plastic body part (41) can be inserted into the second mould section (2) and that a second circumferential cavity (21) is formed on the outside of the edge area (31) to be over-moulded for the production of the second circumferential plastic body part (42), wherein the recess (43) in the first circumferential plastic body part (41) is connected with the second circumferential cavity (21).

9. The injection mould according to claim 8, characterised in that the first cavity (1) has several injection points (12, 12') and several webs (13, 13'), wherein the several injection points (12, 12') are evenly arranged along the first cavity (1) and the several webs (13, 13') are each centrally arranged between two injection points (14, 14').

10. The injection mould according to claim 8 or 9, characterised in that the injection point (12, 12') for the first plastic melt and the injection point (22) for the second plastic melt are located on the same side of the respective mould section (1, 2).