METHOD FOR MANUFACTURING CONTAINERS
Patent Information
- Application Number
- MX2021013957
- Authority / Receiving Office
- MX · MX
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2020-11-13
- Filing Date
- 2021-11-12
- Publication Date
- 2026-02-25
- Estimated Expiration
- 2041-11-12
AI Technical Summary
Existing container manufacturing methods produce significant excess material, leading to high manufacturing costs due to increased raw material prices for thermoplastics.
Reusing excess material by mixing it with virgin thermoplastic material of lower viscosity to form an intermediate layer within the extruded tube, ensuring the outer layer is composed entirely of virgin material, thereby allowing complete separation of the inner and outer containers.
Significantly reduces the amount of virgin material needed, decreasing manufacturing costs while maintaining the ability to separate the inner and outer containers effectively.
Abstract
Description
METHOD FOR MANUFACTURING CONTAINERS FIELD OF INVENTION The invention relates to a method for the continuous manufacture of containers comprising a substantially rigid outer container and an easily deformable inner bag made of a first and second thermoplastic material, which do not form a welded connection with each other, wherein the first thermoplastic material for the outer container is supplied to a first screw conveyor and the second thermoplastic material for the inner bag is supplied to a second screw conveyor, which are connected to an extruder nozzle, which co-extrudes a preform consisting of two tubes, which is disposed between the open halves of a blow mold, wherein the blow mold is closed when the preform has the length required for the manufacture of the container.wherein the excess material in the base area of the container to be manufactured is squeezed out and a band is formed from the welded material of the outer container, wherein the seam of the welded base of the inner bag is grasped and held in the axial direction, and wherein the preform is inflated by a pressure means to couple with the wall of the blow mold and is removed from the blow mold, after which the inner bag is separated from the wall of the outer container. BACKGROUND OF THE INVENTION One such method is described in EP 1 996 384 B1, which refers to how the inner bag of the container is completely separated from the outer container wall. This separation is a prerequisite for the container contents to be completely discharged from the container opening. The inner bag may not form a welded connection with the outer bag at any point, as this would prevent it from being completely separated. In the previous method, the excess material squeezed from the base area of the container to be manufactured—consisting of welded material from the outer container and material from the inner bag held between them—is discarded or given to third parties for less demanding applications. Since the described method produces a considerable amount of excess material that is removed from the manufacturing process, this contributes to relatively high manufacturing costs for the containers, particularly because the prices of raw materials for the thermoplastic plastics used have increased considerably in the meantime and are expected to continue rising. BRIEF DESCRIPTION OF THE INVENTION The objective of the present invention is to provide a method of manufacturing containers, consisting of a rigid outer container and an easily deformable inner bag, in which manufacturing costs are reduced. This objective is achieved in accordance with the invention by means of the features of claim 1. The advantageous embodiments of the invention are characterized in the dependent claims. MA / a / zuzi / ui oyor The invention provides that the excess material is fed back to the first screw conveyor, which mixes the excess material with the first thermoplastic material and supplies it to the extruder nozzle. There, the first thermoplastic material, being virgin material, has a lower viscosity in the molten state than the reused excess material, so that the outer layer of the extruded tube consists exclusively of the first thermoplastic material. Surprisingly, an intermediate layer forms in the extruded tube from the excess material, and outer layers form on both sides from the first thermoplastic material due to the different viscosities, so that no excess material is exposed in the outer layer of the extruded tube.Therefore, after removing the inflated preform from the blow mold and allowing it to cool, the inner bag can be completely separated from the outer container wall, just as it would be if only virgin material had been used for both layers of plastic. As a result of this reuse of excess extruded material, the amount of virgin thermoplastic material used in the initial stage can be significantly reduced, thus lowering the container's manufacturing costs. The two thermoplastic plastic materials are preferably supplied to the respective screw conveyors in the form of granules. Excess material can be fed back to the first screw conveyor untreated, so manufacturing occurs in an in-line process. Alternatively, excess material can be crushed in an additional method step before being fed to the first screw conveyor. In an alternative offline process, the excess material is collected and processed to form a granule before it is fed to the first screw conveyor, which may be a component of a machine operating in parallel. The method according to the invention is also surprisingly usable when a high proportion of the excess material is used. This proportion of excess material in the mixture with the first thermoplastic material can be up to 75% by weight, although a proportion of 70% by weight is particularly preferred. Even with these high proportions of excess material in the outer container to be formed, the excess material on the outer surfaces of the extruded tube is completely covered by the virgin material, which prevents welding to the inner coupling bag from occurring at any point. PP, PET-G, PCTG, PA, and HDPE are preferably used as materials for the outer container, while the inner bag may preferably consist of Lupolen or Surlyn. However, the inner bag may also consist of two or three layers, for example, EVOH, an adhesion-promoting layer, an ionomer, or LDPE. The invention is not limited to the use of the aforementioned materials. The invention provides that in the manufacture of containers, which may have an outer container with a wall thickness of only 1 to 1.5 mm, this outer container can be formed primarily from the excess material squeezed out in the previous manufacturing cycle, wherein the excess material is completely surrounded externally by virgin material used in a substantially smaller quantity, so that the excess material is not exposed at any point MA / a / zuzi / ui oyor on the outer surface of the extruded plastic tube. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a container in accordance with the invention. Figure 2 is a detailed cross-section of the container layers. DETAILED DESCRIPTION OF THE INVENTION Container 1 consists of a rigid outer container 2 and a deformable inner bag 3. The wall of the outer container consists of an intermediate layer 4 of recycled material and on both sides outer layers 5 of virgin material.
Claims
1. A method of manufacturing containers comprising a substantially rigid outer container and an easily deformable inner bag made from first and second thermoplastic materials not welded together, wherein the first thermoplastic material for the outer container is fed to a first screw conveyor and the second thermoplastic material for the inner bag is fed to a second screw conveyor, both connected to an extruder nozzle that co-extrudes a preform consisting of two tubes, arranged between the open halves of a blow mold, the blow mold being closed when the preform is of the length required for manufacturing the container, and wherein excess material in the base area of the container to be manufactured is squeezed out and a strip is formed from the outer container material.wherein the seam of the welded base of the inner bag can be fixed and secured in the axial direction, and wherein the preform is inflated by a pressure means in coupling with the wall of the blow mold and removed from the blow mold, after which the inner bag is detached from the wall of the outer container, characterized in that the excess material is fed back to the first screw conveyor, which mixes the excess material with the first thermoplastic material and supplies it to the nozzle of the extruder, wherein the first thermoplastic material has a lower viscosity in the molten state than the excess material, so that the outer layer of the extruded tube consists solely of the first thermoplastic material.
2. The method according to claim 1, further characterized in that the two thermoplastic plastic materials are supplied to the screw conveyors in the form of granules.
3. The method according to one of claims 1 or 2, further characterized in that the excess material is fed back to the first untreated screw conveyor.
4. The method according to one of claims 1 or 2, further characterized in that the excess material is crushed before being supplied to the first screw conveyor.
5. The method according to one of claims 1 or 2, further characterized in that the excess material is processed into a granulate before being supplied to the first screw conveyor.
6. The method according to any one of claims 1 to 5, further characterized in that the proportion of the excess material in the mixture is < 75% by weight, preferably < 70% by weight.
7. The method according to any one of claims 1 to 6, further characterized in that PP, PET-G, PCTG, PA or HDPE are used as the material for the first or second thermoplastic plastic material.
8. The method according to any one of claims 1 to 7, further characterized in that Lupolen or Surlyn is used as the material for the second thermoplastic plastic material.