CH716689A1 - Fiber-based container and method of manufacture. - Google Patents

Abstract

A fiber-based container (100) made of compressed pulp is described with a container body (20), a container base (10) arranged at a first end of the container body (20) and a second end of the container body opposite the first end of the container body (100) (100) arranged container neck (30). This has an opening. The container bottom (10) is curved outwards. The container base (10) has a wall thickness (k) and at least one support element (11) with a thickness (h) is arranged on the container base (10). The thickness (h) is smaller than the difference between an application thickness (b) of the wet pulp and the wall thickness (k).

Description

The present invention relates to a fiber-based container and a method for producing a fiber-based container according to the preamble of the independent claims.

Different containers for holding liquid are known from the prior art. For example, glass bottles or plastic bottles for holding beverages have become known. Containers made from fiber-based material have also been proposed.

A fiber-based container has been proposed in WO 2012/139590 A1. To manufacture this container, so-called pulp is placed in a mold and pressed against a corresponding wall with a flexible balloon in this form and compressed accordingly.

Pulp is a mixture of fibers and water, in particular natural fibers such as hemp fibers, cellulose fibers or flax fibers or a mixture thereof. The pulp may have additives, as known for example from PCT / EP2019 / 076839, which, for example, improve the hardening of the compressed pulp or influence the later appearance or generally change the properties of the pulp or the later container.

With these containers there is a risk that they will soften due to the liquid stored in the container and, for example, become leaky or that substances will diffuse from the container into the liquid.

It has been proposed to provide such fiber-based containers with an inner layer made of plastic, in particular to arrange a plastic bottle within the fiber-based container, which can take on appropriate barrier functions. Such a combination has become known from WO 2018/167192 A1. The container from WO 2018/167192 A1 has a concave, that is to say inwardly curved, bottom with protuberances. The plastic bottle located inside the container is very thin-walled and has no structural strength. Fiber-based containers have the property that they tend to relax under the action of force. Under constant force there is therefore the risk that the container will deform on the one hand and can no longer be stored upright and the container will also change its volume or fail completely. The container of WO 2018/167192 A1 is therefore not suitable for pressurized liquids.

It is the object of the invention to eliminate one or more disadvantages of the prior art. In particular, a container is to be created which is suitable for holding carbonated liquids, is preferably less prone to deformation and, in particular, can be easily stored and / or transported.

This object is achieved by the devices and methods defined in the independent claims. Further embodiments emerge from the dependent claims.

A fiber-based container made of compressed pulp according to the invention comprises a container body, a container bottom arranged at a first end of the container body and a container neck arranged at a second end of the container body opposite the first end of the container body. The container neck has an opening. The bottom of the container is curved outwards. The entire container bottom is preferably designed as an outwardly directed curvature. The container base has a wall thickness and at least one support element with a thickness is arranged on the container base. This thickness of the support element is smaller than the difference between an application thickness of the wet pulp and the wall thickness of the container bottom.

As already explained, pulp is a mixture of fibers and water or a water-based solution. Here and in the following it is assumed that pulp typically has a moisture content between 96% and 99.8%. Different values may be possible, but these values should be used as a basis for better comparability. Based on a finished product, these values should be used accordingly. In other words, if tests are carried out on a finished product to determine the change in volume between the wet pulp and the finished product, a reference amount of the finished product should be mixed with water until the resulting pulp has a moisture content of 96% to 99.8 % having. The change in volume between the reference product and the pulp produced in the test corresponds to the compression ratio of the pulp towards the finished product during the production process.

In an intermediate step, the fibers are formed into a hollow shell in the shape of the later bottle. In this step the moisture content is between 65% and 78%. With this step, the fibers are kept in an uncompressed form. The order thickness at this point is 3mm to 5mm. Pulp with a moisture content of 65% to 78% can be compressed such that the volume of the pulp is in the ratio of 3.5 to 4.5 to 1 to the volume of the compressed material.

The resulting dry compressed bottle has a wall thickness between 1.5 mm and 0.6 mm.

[0013] An application thickness of the wet pulp is thus preferably at least three times as large and at most 5 times as large as a wall thickness of the finished product and, in the present case, the container bottom. This corresponds to a moisture content of the dry compressed bottle of 1% to 10%, in particular of 5% to 8%.

The ratio of the thickness of the support element in relation to the difference between an application thickness of the wet pulp and the wall thickness ensures that no depressions form on the inside and in particular in the area of the support element during production and that an inner wall of the finished product is essentially flat or is designed to be uniformly curved and, in particular, no turning points of a curvature of the inner wall are formed in the area of the support element. This means that the surface of the inner wall has no turning points in the area of the support element in relation to the general shape of the inner wall, in particular in relation to the general shape of the curvature. The production process can cause deviations between the theoretical shape and the final shape, as well as small depressions. If such deviations from the general shape do not exceed 10% of the wall thickness of the floor, the inner wall has no turning points by definition. With regard to possible depressions, these are not taken into account if they occur in an area that has a diameter that is smaller than the wall thickness of the floor.

The arched design of the container bottom, in particular the design as an outwardly directed curvature, enables forces that act from the inside of the container on the container bottom to be transferred evenly absorbed. An outward deformation of the container bottom and an associated change in volume is no longer possible.

A plastic liner can be arranged within the fiber-based container. The plastic lining can have a neck area with a pouring opening. Elements that correspond to a closure cap, such as, for example, a thread or a sealing area, or possibly hinges or fastening options for a closure cap, can be arranged on the pouring opening.

The plastic lining can be made of polyethylene furanoate (PEF) or polyethylene terephthalate (PET). It can also be made from recycled polyethylene terephthalate (rPET) or a mixture of rPET and PET

A plastic lining prevents later liquid in the container from softening the container. In addition, a plastic lining also prevents substances from the fiber-based container from diffusing into a liquid that is later located in the container.

The pouring opening makes it possible to provide an element on which an interface to a closure element such as a closure cap can be provided in a simple and precise manner.

The plastic lining can have a bottom area which at least partially rests against the inside of the container bottom. The floor area has a wall thickness.

Due to the fact that the plastic lining is in contact with the floor area in some areas, forces which act on the plastic lining can be transmitted to the floor area and thus to the fiber-based container. This means that all forces that can arise inside a container no longer have to be absorbed by the plastic lining. In particular, this enables the container to be used for pressurized liquids such as carbonated beverages.

The support element can have a width and a length, the width being smaller than twice the wall thickness of the container bottom plus three times the wall thickness of the container bottom.

This ensures that the support element is relatively narrow in relation and the risk is reduced that depressions or cavities form in the support element during the production process.

A thickening of the wall thickness, as it is caused by a support element, typically has an influence on a stress distribution in the container. The container is naturally stiffer in those areas in which it is thicker. Stress peaks may occur when transitioning to thinner areas. The smaller the width of the support element, the lower the stress peaks.

Additionally or alternatively, the width of the support element is less than twice the wall thickness of the container bottom plus three times a wall thickness of a deformable, in particular inflatable tool, in particular a balloon, for forming the container.

In addition to the advantages mentioned above with regard to the size ratio of the width of the support element in relation to the wall thickness and the wall thickness, the size ratio of the width of the support element in relation to the dimensions of the inflatable tool ensures that the inflatable tool does not form any formations that extend into a volume of the support element and form corresponding depressions.

The fiber-based container can be designed in such a way that several, preferably three to five or more, support elements are arranged circularly around a longitudinal axis of the container at the same distance from one another and are in particular arranged on the container bottom.

The container can be safely placed on a surface with these support elements.

The support elements can be designed such that, starting from the longitudinal axis, they extend radially outward.

Support elements which extend radially outwards increase the stability. In addition, they can be designed to be teardrop-shaped in their outer contour.

It is also conceivable that the support elements extend essentially circularly around the longitudinal axis in the form of circular ring segments.

This increases the contact surface.

[0033] The support element can also be designed as an elevation that encircles a longitudinal axis of the container in a circular manner.

This creates a single, contiguous support surface.

If necessary, two, three or more, in particular five, support elements can be arranged concentrically. This also increases the support surface and also the stability of the container bottom.

[0036] The container bottom is preferably shaped in a cambered manner.

This essentially corresponds to an outward curvature which affects the entire container bottom.

Preferably, the container bottom is in the form of the bottom of a pressure vessel, in particular in the form of a dished bottom or a basket arch bottom.

Bottoms of this type have only a slightly lower strength in relation to a spherical bottom, which can be compensated for by a corresponding slight thickening of the material.

The container bottom is preferably curved outward in such a way that a curve of the curvature does not have a point of inflection.

This ensures that the ground has a course that does not have any abrupt changes in direction. This in turn has a positive influence on the stress distribution in the container bottom, for example when the container is pressurized.

The fiber-based container is preferably designed in such a way that the container body and the container base are shaped such that a curve in the transition area between the container body and the container base does not have a point of inflection.

This ensures that the container has a course in the transition area that does not have any abrupt changes in direction. This in turn has a positive influence on the stress distribution in the container when the container is pressurized, for example.

Another aspect of the invention relates to a method for producing a container, in particular a fiber-based container as described here. The procedure consists of the following steps: Providing a casting mold with depressions for the formation of support elements, the depressions being designed according to a thickness of the support elements and Introducing wet pulp into the mold.

The application thickness of the wet pulp introduced in the region of the casting mold on which the container base is formed corresponds at least to the sum of the thickness of the support element and the wall thickness of the finished container base

This size ratio ensures that the support elements have no significant negative effect on the drying process and / or when the wet pulp is later compressed in the area of the support element, no depressions or voids are formed and, in particular, a uniform surface profile of an inner wall of the later product and is without turning points.

The introduced pulp can then be compressed with a deformable, in particular inflatable, tool.

By compressing and heat, the moisture can be removed from the wet pulp.

The use of a deformable tool makes it possible to introduce this through a narrow opening into the not yet finished container and to shape the container from the inside, in particular with an outer contour that exceeds a clear diameter of the opening. The deformable tool can, for example, be inflated within the container to a dimension which exceeds the clear diameter of the opening.

The deformable tool can be formed by a heated preform which is blown in the stretch blow molding process. The inflated preform can remain in the container as a plastic lining. An outer wall of the inflated preform rests against an inner wall of the container.

This enables the introduction of a plastic lining and the compression of the wet pulp in a single process step.

Preferably, after the compression of the wet pulp introduced, the container is dried.

The drying of the container can thus be carried out with the desired process parameters.

Alternatively, it can be provided that only after the drying of the fiber-based container for introducing the plastic lining in the container, a heated preform is introduced into the container and inflated in the stretch blow molding process, such that an outer wall of the inflated preform at least partially on an inner wall of the The container.

This makes it possible to provide a complete container, which has correspondingly desired properties in relation to a good to be transported therein, in particular liquid, in order to prevent diffusion of substances from the container into liquid and / or to prevent the fiber-based Container is softened by the liquid in it.

The fiber-based container is preferably designed such that, in generic use, the support elements protrude beyond a lowest point of the container, in this case the container bottom, so that the container only rests on the support elements.

The container can thus be placed safely and steadily on a surface.

The container is preferably a beverage bottle. In particular, a beverage bottle with an opening that is smaller than a largest diameter of a container body.

Several embodiments of a fiber-based container, in particular a container base, are described with the aid of the following schematic figures. It shows: FIG. 1: a fiber-based container; FIG. 2: a perspective view of a support element; FIG. 3: a cross section according to FIG. 2; FIG. 4: The container base from FIG. 1 FIG. 5: Another embodiment of the container base FIG. 6: Another embodiment of the container base FIG. 7: Another embodiment of the container base

FIG. 1 shows a fiber-based container 100 in a partially sectioned view. The fiber-based container 100 includes a container body 20 that has a first end and a second end opposite the first end. A container bottom 10 is arranged on the container body 20 at the first end. At the second end opposite the first end, a container neck 30 with an opening 31 is arranged. The container base 10 is designed as an outwardly curved base, which in the present case is essentially hemispherical.

Between the container bottom 10 and the container body 20 there is a transition area 50. The transition area, in particular the surfaces of the transition area 50, have no turning points. Likewise, there are no turning points in the area of the support elements 11 on the inner surface of the container bottom 10.

For the sake of clarity, the hatching of the sectional view in the area of the container bottom 10 has been omitted.

A plastic lining 40 is arranged in the interior of the container 100. The plastic lining 40 has a neck area 41 and a bottom area 42. The neck area 41 rests on the container neck 30 and the base area 42 rests on the container bottom 10.

The plastic lining 40 is provided with a pouring opening 43, which in turn is closed with a closure cap 44. The closure cap 44 and the pouring opening 43 engage with one another with a thread that is not designated in any more detail.

A support element 11 is arranged on the container bottom 10. The support element 11 projects beyond a lowest point of the container bottom 10 in such a way that the container 100 can be safely placed on the support element 11 in the position shown here.

FIG. 2 shows a perspective view of a support element 11 in a schematic representation. An outer surface of the curved container bottom 10 on which the support element 11 is arranged is shown in dashed lines. The support element 11 has a length L2 and a width L1. In FIG. 2, a sectional plane B is shown which essentially extends through the support element 11 in such a way that the width L1 of the support element 11 is reproduced true to the original.

FIG. 3 shows a cross section according to FIG. 2 through the sectional plane B. Also shown in FIG. 3 is a casting mold 70 in which the container 100 is manufactured. Also shown in the sectional view according to FIG. 3 is a deformable tool 60 with which the wet pulp is compressed. The deformable tool 60 has a wall thickness w.

In the casting mold 70 there is a recess which corresponds to the later support element 11. The recess, like the support element 11, has a thickness h and a width L1. The inner wall of the finished container base 10 is shown with a solid line. The finished container base 10 has a wall thickness k. An application thickness b of the wet pulp is shown with a dashed line.

The thickness h is smaller than the application thickness b of the wet pulp minus the wall thickness k of the finished container bottom 10. This means that the thickness h is smaller than the difference between the application thickness b of the wet pulp and the wall thickness k.

The width L1 of the support element 11 is smaller than the sum of four times the wall thickness h and in particular smaller than the sum of ten times the wall thickness h.

To produce the fiber-based container 100, pressure is applied to an interior of the deformable tool 60 and the section of the deformable tool 60 shown here moves in the direction of the support element 11 and thus compresses the wet pulp down to the wall thickness k. The method for introducing pulp into a corresponding casting mold 70 and the subsequent shaping with a deformable tool 60 is described, for example, in WO 2012/139590 A1. The present container 100 is manufactured essentially in accordance with the method described therein. For the individual process steps for compressing the wet pulp, reference is made to the disclosure of WO 2012/139590 A1.

FIG. 4 shows the container bottom 10 from FIG. 1, on the one hand, in a sectional view and, on the other hand, in a view of the container bottom 10 in the direction of the opening 31 (see FIG. 1 in this regard). The support element 11 is designed as an elevation that encircles a longitudinal axis A (see FIG. 1) in a circular manner. The total length of the support elements in the circumferential direction is less than 70% of the length of the circumference of the base 10 at its largest diameter. In this embodiment it is conceivable that several support elements 11 are arranged concentrically to one another on the container bottom 10.

FIG. 5 shows a further embodiment of a container bottom 10 in a representation corresponding to FIG. In the present case, three separate support elements 11 are arranged on the container bottom 10 of this embodiment and are designed in the form of circular ring segments. The support elements 11 according to this embodiment are arranged circularly around the longitudinal axis A (see FIG. 1) of the container 100 at the same distance from one another. The length of each support element 11 in its circumferential direction is less than a third of the length of the circumference.

FIG. 6 shows a further embodiment of a container bottom 10 in a representation corresponding to FIG. In the present case, five separate support elements 11 are arranged on the container bottom 10 of this embodiment, which are arranged circularly around the longitudinal axis A (see FIG. 1) at the same distance from one another. Starting from the longitudinal axis A, these support elements 11 extend radially outward. The length of each support element 11 in the radial direction corresponds at least to the width of the support element in the circumferential direction and in the present case corresponds to four times the width.

FIG. 7 shows a further embodiment of a container bottom 10 in a representation corresponding to FIG. In the present case, five separate support elements 11 are arranged on the container bottom 10 of this embodiment, which are arranged circularly around the longitudinal axis A (see FIG. 1) at the same distance from one another. These support elements 11 are designed as circular elevations. The length of each support element 11 in the radial direction corresponds at least to the width of the support element in the circumferential direction and in the present case corresponds exactly to the width.

Claims (18)

A fiber-based compressed pulp container (100) comprising a container body (20), a container base (10) arranged at a first end of the container body (20) and a container neck (30) with an opening ( 31), wherein the container bottom (10) is curved outwards, characterized in that the container base (10) has a wall thickness (k) and at least one support element (11) with a thickness (h) is arranged on the container base (10), the thickness (h) being smaller than the difference between an application thickness (b) and the wet one Pulp and the wall thickness (k). 2. Fiber-based container (100) according to claim 1, characterized in that a plastic lining (40) is arranged inside the container (100), the plastic lining having a neck region (41) with a pouring opening (43). 3. Fiber-based container (100) according to claim 2, characterized in that the plastic lining (40) has a bottom area (42) which at least partially rests against an inside of the container bottom (10), the bottom area (42) having a wall thickness (d) having. 4. Fiber-based container (100) according to claim 3, characterized in that the support element (11) has a width (L1) and a length (L2), the width (L1) being smaller than four times the wall thickness (k) of the Container bottom. 5. Fiber-based container (100) according to one of claims 1 to 4, characterized in that several, preferably three to five or more, support elements (11) are arranged circularly around a longitudinal axis (A) of the container (100) at the same distance from one another . 6. Fiber-based container (100) according to claim 5, characterized in that the support elements (11) extend radially outward starting from the longitudinal axis (A). 7. Fiber-based container (100) according to claim 6, characterized in that the support elements (11) extend essentially circularly around the longitudinal axis (A) in the form of circular ring segments. 8. A fiber-based container (100) according to any one of claims 1 to 5, characterized in that the support element (11) is designed as a circularly encircling elevation around a longitudinal axis (A) of the container (100). 9. Fiber-based container (100) according to claim 8, characterized in that two, preferably three to five or more, support elements (11) are arranged concentrically. 10. Fiber-based container (100) according to one of claims 1 to 9, characterized in that the container bottom (10) is cambered. 11. Fiber-based container (100) according to one of claims 1 to 10, characterized in that the container bottom (10) has the shape of the bottom of a pressure vessel. 12. Fiber-based container (100) according to one of claims 1 to 11, characterized in that the container bottom (10) is curved outward so that a curve of the curvature has no point of inflection. 13. Fiber-based container (100) according to claim 12, characterized in that the container body (20) and the container base (10) are shaped so that a curve in the transition region (50) between the container body (20) and the container base (10 ) has no turning point. 14. A method for producing a container (100), in particular a fiber-based container (100) according to one of claims 1 to 13, comprising the steps - Provision of a casting mold with depressions for the formation of support elements (11), the depressions being designed according to a thickness (h) of the support elements - Introducing wet pulp into the mold characterized in that the application thickness (b) of the wet pulp introduced in the region of the casting mold on which the container base (10) is formed is at least the sum of the thickness (h) and the wall thickness (k) of the finished container base (11) corresponds to. 15. The method according to claim 14, characterized in that the introduced wet pulp is compressed with a deformable, in particular inflatable, tool (60). 16. The method according to claim 15, characterized in that the deformable tool (60) is formed by a heated preform which is inflated in the stretch blow molding process and the inflated preform remains as a plastic lining in the container, an outer wall of the inflated preform on an inner wall of the Container (100) is applied. 17. The method according to any one of claims 15 to 16, characterized in that after the compression of the wet pulp introduced, the container (100) is dried. 18. The method according to claim 17, characterized in that after the drying of the fiber-based container (100) for introducing the plastic lining (40) into the container (100), a heated preform is introduced into the container (100) and inflated in the stretch blow molding process that an outer wall of the inflated preform at least partially rests against an inner wall of the container (100).