CH710318A1 - Plastic containers with sealable container mouth. - Google Patents

Abstract

A plastic container (1) is described, which has a container body (2) and a container neck (4) with a container mouth (5) which can be closed with a sealing film. The container mouth (5) is bounded by a closed circumferential orifice surface (8) which is bounded on the outer circumference by an outer surface (9) of the container neck (4) and ends inwardly in a mouth edge (7). At least one closed circumferential welding rib (10) is arranged at the mouth surface (8), which protrudes essentially axially from the mouth surface (8).

Description

The invention relates to a plastic container with a sealable container mouth according to the preamble of patent claim 1.

The usual in the past containers made of white or stained, glass or ceramic are increasingly being replaced by plastic containers. In particular, for the packaging of fluid substances, for example, for household applications, agriculture, industry and commerce, etc., recently mainly plastic containers are used. The low weight and the lower costs certainly play a significant role in this substitution. The use of recyclable plastic materials and the overall more favorable overall energy balance in their production also contribute to promoting the acceptance of plastic containers among the users.

Single-layer or multi-layer plastic containers are often produced by the so-called extrusion blow molding method, in particular a tubular blowing method. The extrusion blow molding machines used for the extrusion blow molding process usually have one or more extruders for feeding the required plastic material. The outlet of the extruder is connected to an extruder head, at the outlet opening of which the extruded tube preferably exits in the opening width. The extruded plastic tube can be constructed in one or more layers. The hose exiting the outlet nozzle continuously or quasi-continuously is transferred to a blow molding tool assembly and inflated by overpressure with the aid of a blow mandrel retracted into the mold cavity. Thereafter, the inflated plastic container is removed from the mold cavity.

Plastic containers made of polyethylene terephthalate (PET) and similar materials are usually produced in a so-called stretch blow molding. In this case, a preform is first produced by injection molding in an injection mold. Recently, also flow molding or extrusion blow molding for the production of preforms have been proposed. The preform has a substantially elongate preform body and is formed closed at its one longitudinal end. At the other end of the preform body includes a neck portion, which is provided with a pouring opening. The neck portion already has the later shape of the bottle neck. On the outer side of the neck portion, therefore, threaded portions or the like protrusions are usually already formed for fixing a closure part. In many cases, a so-called snap ring is provided on the neck portion, which protrudes radially from the circumference. The snap ring serves as an abutment for a detachable guarantee strip of a screw-on screw cap for a plastic container blown out of the preform or for oil bottles or the like for fixing the lower part of a commonly used hinge closure. In most of the known preforms, the preform body and the neck portion are separated by a so-called support ring. The support ring protrudes radially and serves for the transport of the preform or of the plastic container produced therefrom and for the support of the preform on the molding tool or of the plastic container during the closure.

The preform is removed from the mold after its production and can be further processed immediately hot in a single-stage stretch blown or cooled and stored in a two-stage stretch blow molding for spatially and / or temporally separate processing on a stretch blow. Before further processing in the stretch blow molding apparatus, the preform is conditioned if necessary, i. The preform is impressed on a temperature profile. Thereafter, it is introduced into a blow mold of the stretch blow molding apparatus. In the blow mold, the preform is finally inflated by means of a gas injected with overpressure, usually air, according to the mold cavity and additionally axially stretched with a stretching mandrel. An injection blow molding process is also already known, in which the blowing process takes place directly after the injection of the preform. The preform remains on the injection core, which at the same time forms a kind of stretching mandrel. The preform is in turn inflated by overpressure according to the mold cavity of a blow mold, which is delivered to the injection core or vice versa, and thereby stretched by the mandrel. Thereafter, the finished plastic container is removed from the mold.

The extrusion blown, injection blown or stretch blown plastic containers are i.d.R. transported and filled immediately after demoulding to a bottling plant.

After the filling process, in particular, plastic containers containing foods, e.g. Milk, milk powder, powder for instant drinks, yoghurt drinks and the like, sauces, etc., usually sealed with a sealing foil. In addition, even a screw or snap closure can be attached. The sealing film on the one hand serves as a barrier against oxygen, moisture and any germs and on the other hand as an indicator for the opening safety.

The application of the sealing film on a container mouth is usually carried out by an inductive welding. In this case, a cohesive connection between an outer layer of the sealing film and the plastic material is created at the adjacent container mouth. The energy required for the sealing process depends to a large extent on the plastic materials to be bonded to one another, on the one hand, of the sealing film and, on the other hand, of the container mouth. The uniformity or flatness of the container mouth also plays a major role. The energy for the sealing process is usually applied flat over a sealing plate, by means of which the sealing film is pressed against the container mouth.

For smaller and / or rotationally symmetrical container mouths can still be assumed that a relatively uniform pressure distribution. In container mouths with larger diameters of, for example, 30 mm and larger and especially deviating from the rotational symmetry container mouths, such as often occur in so-called wide-necked containers, it may come to a non-uniform contact pressure of the sealing foil against the container mouth due to different stiffness over the circumference of the container mouth. In order nevertheless to ensure a reliable welding of the plastic materials during the sealing process, this is usually done with a relatively large amount of energy and a relatively high contact pressure. Due to the relatively large amount of energy used in the sealing process, however, undesired deformations may occur in the region of the free mouth edge of the container mouth. These can occur in particular at relatively narrow, sharp-edged mouth edges. This can be the case, for example, with wide-necked containers, which are manufactured according to the so-called "lost-neck method". Such containers are first inflated like a plastic bottle in the mold cavity of a blow mold. Here, in a subsequent directly to the container body portion fastening means such as threaded portions, a thread, projections, groove-like depressions or the like are blown for the positive fixing of a closure. Subsequent to the blowing process, a neck section of the plastic container located above the blown fastening means for the positive locking of the closure is cut off. The relatively sharp cutting edge forms the mouth edge of the container mouth, which has a relatively large and often deviating from the circular opening diameter.

Object of the present invention is therefore to remedy the problems described that can occur when applying a sealing film on a container mouth. It is intended to create a plastic container in which the risk of deformation in the area of the container mouth during the sealing process is reduced, if not eliminated.

The solution to these problems consists in a plastic container, which have the stated in the characterizing portion of claim 1 features. Further developments and / or advantageous embodiments of the invention are the subject of the dependent claims.

The invention provides a plastic container is provided which has a container body and a container neck with a container mouth, which is closable with a sealing film. The container mouth is bounded by a closed circumferential muzzle surface which is bounded on the outer circumference of the container mouth by an outer surface of the container neck and ends inwardly in an inner mouth edge. At least one closed circumferential welding rib is arranged at the mouth surface, which protrudes essentially axially from the mouth surface.

The at least one arranged on the mouth surface welding rib facilitates the sealing process. The energy required for the welding of the plastic partners involved is no longer distributed over the entire mouth area of the container mouth, but rather it is concentrated on the welding rib, in particular on the most elevated area of the same. As a result, the sealing process can be carried out with a reduced input of energy and with a lower contact pressure, and undesirable deformations of the inner mouth edge can be reduced or prevented. The reduced compared to the prior art energy expenditure for the sealing process represents a further advantage of the invention formed plastic container.

In that the at least one welding rib has a greater width on a base merging into the mouth surface than on an axially projecting region, the energy input into the welding rib can be concentrated even better and the sealing process can be improved.

In one embodiment of the plastic container, the at least one welding rib may have a substantially triangular cross-section. The sides of the triangular weld rib enclose with the mouth of the mouth of the container at an angle which is from 15 ° to 75 °. The angle of inclination of the sides of the welding rib in the stressed area facilitates the production of the welding rib, for example its removal from the corresponding area of the blow mold.

In an alternative embodiment of the plastic container, the at least one welding rib may have a curved cross-sectional contour. The curved cross-sectional contour may, for example, run in a circular arc or sinusoidal manner. Also, such cross-sectional contours are easy and easy to produce with the manufacturing method described in more detail below.

A further variant of the plastic container may provide that the at least one circumferential welding rib is formed differently high relative to the mouth surface. In particular, the at least one welding rib in those areas of the container mouth, in which the container neck offers a lower resistance to the contact pressure of the sealing plate, can be made higher. In the higher-trained areas, the at least one welding rib may also have a broader base at the transition to the mouth area. In this way, due to the container geometry different axial stiffnesses of the container neck or of the container relative to the contact pressure during the sealing process can be compensated.

In a plastic container, which may be formed, for example, as a wide-mouth container and having a substantially rectangular container mouth, the at least one circumferential weld rib at the corners of the container mouth relative to the mouth surface may have a lower height than in a center portion of each side of the container mouth , Due to the greater height of the at least one welding rib in the middle of the page, the lower rigidity of the container neck compared with the corners is compensated for there. The increase in height from the corners to the respective side center can for example be continuous.

A further embodiment of the plastic container may provide that protrude from the mouth surface two or more closed circumferential welding ribs, which have a radial distance from each other. For example, two closed circumferential welding ribs may be arranged at a radial distance of about 0.5 mm to 4 mm from each other. The provision of multiple welding ribs can provide an even better material bond between the sealing film and the plastic material at the container mouth.

In the case of two or more radially spaced welding ribs may have this manufacturing reasons, each having a similar cross-sectional contour. For example, two approximately triangular welded ribs may be provided. Alternatively, the mouth surface can have an approximately sinusoidal profile over at least a partial region of its radial extent, or two or more welding ribs with a rounded cross section can be provided.

So that the energy input takes place as early as possible on the welding rib during the sealing process, it may prove expedient if the plastic container has a measured over the weld rib (s) second axial length within a range of measured over the inner mouth edge first axial Length plus 1 mm or minus 0.5 mm.

For the sealing process, it may prove to be expedient if the plastic container has at least one welding rib, which is designed such that a straight line axially projecting portion of the welding rib and the mouth edge connecting straight line with a container axis an angle greater than or equal to 90 ° includes. In the case of a plurality of radially spaced apart welding ribs, the axially most protruding portions of the additional welding ribs are also on this straight line.

The inventive plastic container may be made in a blow molding process. Blow molding processes in which a preform in a blow mold is expanded by a gas injected with overpressure, usually air, according to the cavity of the blow mold, are well known and widely tested.

A variant of the invention may provide that the plastic container is made in a stretch blow molding from a preform previously made. The stretch blow molding process may be a one or two stage stretch blow molding process. Since the neck section of the preform is usually no longer changed in the stretch blow molding process, the at least one welding rib is already formed on the preform. The preform can be produced, for example, in an injection molding process or in a flow molding process. It is also possible to produce the preform in an extrusion blown process.

In a variant of the plastic container produced in a stretch blow molding process, the at least one welding rib already provided on the preform can be produced by an additive application of material to the mouth surface. In this case, the at least one welding rib can be produced, for example, in a two-component injection molding process in which e.g. First, a plastic material forming the welding rib (s) is introduced into the injection mold before the actual preform is sprayed in a further operation. In an alternative production variant of the preform, the preform is first injection-molded or produced in a flow-molding process. Thereafter, in one further step, one or more welding ribs can be applied to the mouth area.

In an alternative embodiment, the plastic container may be produced in an extrusion blow molding process. In this case, a single or multilayer extruded plastic tube is extruded, cut to length and inflated in a blow mold according to the mold cavity.

The extrusion-blown plastic container may be formed in a further embodiment as a wide-mouth container, which is manufactured in a "lost-neck process". Initially, usually in an extrusion blow molding process, an intermediate plastic container is produced. The later mouth area with the at least one closed circumferential welding rib is produced during the blowing process. Thereafter, the intermediate plastic container is cut in the region of the mouth area in order to separate the section located above. The container mouth is created. When cutting the relatively sharp-edged mouth edge is generated. Depending on the axial height of the weld rib (s), the cut may be horizontal, i. perpendicular to the container axis, or obliquely. The axial height of the mouth edge can be up to 5 mm above the axial height of the at least one welding rib. Advantageously, however, the cut is made such that the axial height of the inner muzzle edge is flush or up to 1 mm lower than the axial height of the at least one welding rib.

The wide-mouth container may have a container body and / or a container neck with a non-circular cross-section. Such wide-mouth containers are often used as containers for powdery filling material. The non-circular cross-section facilitates the removal of the contents, for example with a dosing spoon. As a wide-neck container in the context of the present invention, a plastic container is designated, the container mouth has an area of 700 mm 2 or more.

The wide-mouth container can be made in a further alternative also from a manufactured in a stretch blow molding plastic container in a «lost-neck process. The mouth area with the at least one welding rib is produced in the blow mold. The inner mouth edge results after cutting the stretch blown auxiliary container.

The inventive design is applicable to a wide variety of types of plastic containers, especially plastic bottles. The plastic container may be formed one or more layers. The only condition is that it is made for the blowing method used in each case, i. E. is made for a stretch blow molding process with previous injection molding or flow molding process or for an extrusion blow molding process, suitable plastics. Examples of such plastics are PET, PET-G, HDPE, PET-X, PP, PS, PVC, PEN, copolymers of the cited plastics, bioplastics such as PLA or PEF, filled plastics and mixtures of said plastics.

Further advantages and features will become apparent from the following description of exemplary embodiments of the invention with reference to the schematic drawings, which are not shown to scale. <Tb> FIG. Fig. 1 shows a view of a plastic container, in particular a wide-mouth container, produced by a lost-neck method; <Tb> FIG. Fig. 2 shows an enlarged axial section of a container mouth portion of a container neck; <Tb> FIG. FIG. 3 shows a variant of a portion of a container neck having a container mouth in a representation analogous to FIG. 2; FIG. and <Tb> FIG. 4 and FIG. 5 show two further variants of a section of a container neck having a container mouth in a representation analogous to FIG. 2.

Fig. 1 shows a schematic representation of a trained as a wide-mouth container plastic container, which is made by a lost-neck process. It can be made in a blow-molding process, for example in an extrusion blown from an extruded plastic tube or in a stretch blown from a preform previously made, for example, in an injection molding or in a flow molding process. The container 1 may be constructed in one or more layers and accordingly comprises one or more layers of the plastic materials commonly used for these methods, e.g. PET, PET-G, HOPE, PET-X, PP, PS, PVC, PEN, copolymers of the cited plastics, bioplastics, such as PLA or PEF, filled plastics and mixtures of said plastics. The illustrated in Fig. 1 separated neck portion 40 is intended to indicate the production in the Lost-Neck process from a previously produced by blow molding intermediate plastic container. The wide-mouth container 1 has a container body 2, which is closed by a container bottom 3. At its longitudinal end opposite the container bottom 3, the wide-mouth container 1 has a container neck 4 with a relatively large mouth opening 5, which is produced by cutting the intermediate plastic container. As a wide-neck container, a plastic container is designated for this invention, the mouth opening 5 has a surface greater than or equal to 700 mm2. At its container neck 4, the plastic container can be equipped with fastening means 6 for the positive fixing of a closure part, which are formed by the blowing process. The fastening means 6 may be formed as threaded portions, locking projections, or as correspondingly formed female threaded portions, grooves or the like.

Fig. 2 shows a portion of the container neck 4 in an enlarged axial section. The container mouth is provided with the reference numeral 5. The container mouth is bounded by a closed circumferential muzzle surface 8, which is bounded on the one hand by an outer surface 9 of the container neck 4 or merges into it and ends in the direction of the container mouth 5 in an inner mouth edge 7. At least one closed circumferential welding rib 10 rises from the mouth surface 8. The mouth surface 8 with the welding rib 10 are formed in a blow mold during the production of the wide-mouth container 1 by blow molding. The relatively sharp-edged mouth edge 7 results from the separation of the neck portion located above the mouth surface 8 (reference numeral 40 in FIG. 1) of the intermediate plastic container. According to the embodiment shown in FIG. 2, the welding rib 10 has an approximately triangular cross-section. In this case, welding rib 10 is wider at its merging into the mouth surface 8 base than at its axially furthest the mouth surface 8 superior area. The sides of the triangular welding rib 10 enclose with the mouth surface 8 of the container mouth 5 at an angle which is from 15 ° to 75 °.

FIG. 3 shows, in an axial section analogous to the representation in FIG. 2, an alternative embodiment variant of the at least one welding rib, which in turn is provided with the reference numeral 10. The schematically illustrated welding rib 10 has, according to the embodiment shown, a curved cross-section. Again, it is wider at its base than at its mouth area 8 furthest towering area. With the axial height of the inner mouth edge 7 as a reference large, the most projecting portion of the welding rib 10 opposite the mouth edge on an axial height difference of + 1 mm to -0.5 mm. In other words, the wide-mouth container has a second axial length b measured over the welding rib 10, which is within a range of a first axial length a measured over the inner mouth edge 7 plus 1 mm and 0.5 mm, respectively. In this case, the at least one welding rib 10 with respect to the mouth surface 8 does not have to have the same height everywhere. The at least one peripheral welding rib 10 may be formed higher in those areas of the mouth surface 8, which has a lower resistance due to the container geometry compared to the contact pressure of the sealing plate. In the higher-trained areas, the at least one welding rib 10 at its transition into the mouth area 8 may have a wider base area than at the pressure-stable areas. For example, in containers having a substantially rectangular container mouth, the welding fin may continuously increase from the corners of the container mouth to the center of the respective side of the container mouth. Thereby, the different resistance of the container neck 4 can be better compensated against the contact pressure of the sealing plate.

A comparison of the two embodiments of the welding rib 10 according to FIG. 2 and according to FIG. 3 further shows that the distance between the at least one welding rib 10 from the inner mouth edge 7 can be of different sizes. The distance depends on the radial length of the mouth surface 8, on the wall thickness in the region of the mouth surface 8 and on the geometry of the container mouth. The radial length of the mouth surface 8 is for example 1.5 mm to 4 mm. A relatively small, rotationally symmetrical container mouth usually gives the mouth surface a greater rigidity. Accordingly, the welding rib 10 may be arranged closer to the mouth edge 7. In the case of a non-rotationally symmetrical geometry of the container mouth, it may be expedient if the welding rib 10 is arranged at a greater distance from the mouth edge 7.

In Fig. 4 and 5, two further embodiments of an inventively designed plastic container are shown. In particular, a plurality of, for example two, closed circumferential welding ribs 10, 10 are arranged on the mouth surface 8 and extend at a radial distance from one another. The welding ribs 10, 10 can have a substantially triangular cross-section (FIG. 4) or they can have a curved contour (FIG. 5). The welding ribs 10,10 may be formed such that a straight line t, which connects the most axially projecting portions of the welding ribs 10,10 and the inner mouth edge 7, with an axis A of the plastic container encloses an angle α, the same or greater than 90 °. Preferably, the welding ribs 10, 10 of a variant each have a similar cross-sectional contour. From the illustration in Fig. 5 it can be seen that the two radially spaced welding ribs 10, 10 may for example have an approximately sinusoidal course.

The invention has been explained using the example of a container mouth of a wide-mouth container. It is understood that the embodiment according to the invention can also be used in other plastic containers with a sealable container mouth. By way of example, the plastic container can be produced in a stretch blow molding method from a previously produced preform. The stretch blow molding process may be a one or two stage stretch blow molding process. Since the neck section of the preform is usually no longer changed in the stretch blow molding process, the at least one welding rib can already be formed on the preform. The preform can be produced, for example, in an injection molding process or in a flow molding process. It is also possible to produce the preform in an extrusion blown process. The at least one welding rib provided on the already preform can also be produced by an additive application of material to the mouth surface. In this case, the at least one welding rib can be produced, for example, in a two-component injection molding process in which e.g. First, a plastic material forming the welding rib (s) is introduced into the injection mold before the actual preform is sprayed in a further operation, from which the desired plastic container is subsequently produced in a blow molding process. In an alternative production variant of the preform, the preform is first injection-molded or produced in a flow-molding process. Thereafter, in one further step, one or more welding ribs can be applied to the mouth area.

Claims (17)

1. A plastic container with a container body (2) and a container neck (4) with a container mouth (5), which is closable with a sealing film, characterized in that a container mouth (5) bordering closed circumferential orifice surface (8) of a Outer surface (9) of the container neck (4) is limited and ends inwardly in an inner mouth edge (7), at least one closed circumferential weld rib (10, 10) which emerges substantially axially from the mouth surface (8). 2. Plastic container according to claim 1, characterized in that the at least one welding rib (10, 10) on a in the mouth surface (8) merging base has a greater width than at an axially projecting portion. 3. Plastic container according to claim 2, characterized in that the at least one welding rib (10, 10) has a substantially triangular cross-section. 4. Plastic container according to claim 2, characterized in that the at least one welding rib (10, 10) has a curved cross-sectional contour. 5. Plastic container according to one of the preceding claims, characterized in that the at least one circumferential weld rib (10) relative to the mouth surface (8) is formed differently high. 6. Plastic container according to claim 5, characterized in that the at least one circumferential welding rib (10) at a substantially rectangular container mouth (5) at the corners of the container mouth (5) relative to the mouth surface (8) has a lower height than in a Center section of each side of the container mouth (5). 7. Plastic container according to one of the preceding claims, characterized in that of the mouth surface (8) protrude two or more closed circumferential welding ribs (10, 10) which have a radial distance from each other. 8. Plastic container according to claim 7, characterized in that the welding ribs (10, 10) each have a similar cross-sectional contour. A plastic container according to any one of the preceding claims, characterized in that a second axial length (b) of the container (1) measured over the welding rib (s) (10, 10) is measured within a range of one above the inner mouth edge (7) first length (a) plus 1 mm or minus 0.5 mm. 10. Plastic container according to one of the preceding claims, characterized in that a straight line (t) which connects a most axially projecting region of a welding rib (10, 10) and the inner mouth edge (7) with a container axis (A) a Angle (α) greater than or equal to 90 ° included. 11. Plastic container according to one of the preceding claims, characterized in that it is produced in a blow molding process. 12. Plastic container according to claim 11, characterized in that it is designed as a wide-mouth container and produced in a "lost-neck process". 13. Plastic container according to claim 11, characterized in that the container body (2) and / or the container neck (4) have a non-circular cross-section. 14. Plastic container according to claim 11, characterized in that it is produced in a stretch blow molding from a preform previously made and the at least one welding rib (10, 10) is already formed on the preform. 15. Plastic container according to claim 14, characterized in that the at least one welding rib (10, 10) is produced by an additive material application to the mouth surface (8). 16. Plastic container according to claim 11, characterized in that it is produced in an extrusion blow molding process. 17. Plastic container according to one of the preceding claims, characterized in that it is formed one or more layers and PET, PET-G, HDPE, PET-X, PP, PS, PVC, PEN, copolymers of the cited plastics, bioplastics, such as PLA or PEF, filled plastics and mixtures of said plastics.