WO2016114654A1

WO2016114654A1 - Injection-molded box, preferably suitable as a coffin, method for injection-molding such a box

Info

Publication number: WO2016114654A1
Application number: PCT/NL2016/050020
Authority: WO
Inventors: Anna Maria HAVERMANS
Original assignee: Onora B.V.
Priority date: 2015-01-13
Filing date: 2016-01-12
Publication date: 2016-07-21
Also published as: NL2014128A; NL2014128B1

Abstract

Injection-molded box, preferably suitable as a coffin, comprising a bottom wall and upright walls connected to the latter, which is made from a plastic which comprises a bio-based plastic as its main component, wherein the bio-based plastic comprises polylactic acid, and wherein the bottom wall is provided with a reinforcing structure, characterized in that the design of the reinforcing structure is such that adjacent walls within the reinforcing structure satisfies a modified release angle of at least 3 degrees, preferably at least 6 degrees, and most preferably at least 10 degrees.

Description

Injection-molded box, preferably suitable as a coffin, method for injection-molding such a box

The present invention relates to an injection-molded box, preferably suitable as a coffin, comprising a bottom wall and upright walls connected to the latter, which is made from a plastic which comprises a bio-based plastic as its main component, wherein the bio- based plastic preferably comprises polylactic acid, and wherein the bottom wall is provided with a reinforcing structure. Traditional coffins are based on wood materials of different qualities. The chosen material is thus used once and eventually decays over time in the case of a burial, or directly in the case of a cremation. The selection of wood material is undesirable, in view of the single and finite use for a coffin, on account of the environmental load and the required manufacturing steps.

The use of a biodegradable plastic has already been considered as an alternative for wood material. An example thereof is an injection-molded coffin of polyvinyl alcohol, as described in European patent application EP2796122. It is even more attractive to use a bio-based plastic as material for a coffin, which is known per se from international application WO 2006/075911.

However, in practice, the manufacture of such a coffin appears to have drawbacks which are related to the injection-molding process. After injection-molding the coffin in an injection mold, it is left to cool down, following which the upper half of the mold is removed and the product is then demolded from the bottom half of the mold. It has been found that demolding the coffin from the bottom half of the mold is more complicated with an injection-molded coffin made of bio-based plastic compared to one made of conventional plastic. The removal of the upper half of the mold may also cause problems. Demolding is particularly problematic at the location of the reinforcing structure. As a result thereof, good demolding of the product is not possible, as a result of which the product may tear and lose its integrity. In particular, it has been found that a coffin which is provided with a reinforcing structure in the form of conventional ribs or upright walls in the form of a honeycomb structure does not detach well from the injection mold, with parts of the reinforcing structure breaking off.

A first aspect which may play a part with regard to good detachment of an injection- molded object is the release angle which is particularly important if an object contains relief structures which point upwards as elevated portions, the shape of which has been determined by the bottom mold from which the object is demolded, or which point downwards as recessed portions, the shape of which has been determined by the upper mold. In this context, these are also referred to as depth structures. Viewed in cross section, an elevated, upwardly pointing structure has two adjacent walls which have to converge towards one another in an upward direction to some degree in order to facilitate demolding. To this end, each wall is at a small angle compared to the situation where the walls are arranged parallel to one another. The angle at which the wall is arranged is referred to as the release angle and usually the same angle is chosen for adjacent walls, resulting in a symmetrical arrangement. A release angle of 0 degrees for two neighboring walls thus means a parallel arrangement of the walls. The same considerations as above apply in the case of a recessed, downwardly pointing structure, but in the opposite direction.

Normally a relatively small release angle of 0.5 to 2.5 degrees is used in the case of injection-molding objects comprising depth structures. However, this has been found to be insufficient for a coffin as claimed in the present invention. When molding relatively large structures, such as a coffin, the problems surrounding demolding become even greater.

It is an object of the invention to completely or largely prevent the abovementioned problems which occur when manufacturing an injection-molded box made of a bio- based plastic.

To this end, as claimed in a first aspect, the invention relates to

an injection-molded box, preferably suitable as a coffin, comprising a bottom wall and upright walls connected to the latter, which is made from a plastic, which comprises a bio-based plastic as its main component, wherein the bio-based plastic preferably comprises polylactic acid, and wherein the bottom wall is provided with a reinforcing structure,

characterized in that the design of the reinforcing structure is such that opposite adjacent walls within the reinforcing structure meet at a modified release angle of at least 3 degrees, preferably at least 6 degrees, and most preferably at least 10 degrees.

During tests, it has been found that a release angle of at least 3 degrees is required for an injection-molded box made of a plastic whose main component is a bio-based plastic comprising polylactic acid. Depending on the exact design of the box, it is advantageous in some cases to maintain a release angle of at least 6 degrees and, in specific cases, an angle of at least 10 degrees is even required. In exceptional cases, a release angle of 15 degrees may be preferred.

In the context of the invention, the modified release angle may also apply to other structures of the box, such as oppositely arranged side walls or portions of these side walls.

The bio-based plastic which is used with the invention preferably comprises polylactic acid and appears to be readily suitable for the intended applications.

In this context, a plastic containing a bio-based plastic as its main component means that at least 40% by weight of the raw materials of the plastic overall come from a renewable biological source.

Preferably, at least 60% by weight or even 80% by weight or up to 90% by weight of the raw materials of the plastic overall come from a renewable source. Thus, the invention produces as little environmental pollution as possible.

The abovementioned levels may, for example, relate to polylactic acid.

More preferably, the plastic from which the injection-molded box as claimed in the invention is made is a plastic which is biodegradable. Advantageously, this plastic is additionally compostable, that is to say at least 95 percent thereof are biodegradable at an industrial composting company within 12 weeks. A plastic whose main component is polylactic acid has these properties. With the box as claimed in the invention, the bottom wall is provided with a reinforcing structure. Such a box is suitable for carrying a heavy load, preferably a load of at least 120 kg. The reinforcing structure may be configured as a modified surface structure of the bottom wall, as a thickened section, or as a combination of both.

The box preferably has a rectangular shape, with for example the length being at least twice the size of the width. Suitable and preferred dimensions of the box are a length of approx. 2 meters, a width of 60 to 70 cm and a height of approx. 40 cm. These numerical dimensions may vary in such a manner that the length, width and height may each separately be up to 25% smaller or larger.

It is particularly preferred if the reinforcing structure in the injection-molded box as claimed in the invention comprises elevated portions and recessed portions which are configured as elongate ribs and elongate grooves, respectively.

Such a structure has been found to be very efficient in order to be able to carry relatively heavy loads, without the bottom wall sagging or otherwise deforming.

More preferably, the ribs and grooves in the injection-molded box as claimed in the invention are rounded. The rounding of ribs and grooves facilitates demolding as there are no angle-shaped seams or edges. Such seams or edges can often make good demolding more difficult.

In a next aspect, it is preferred if the ribs and grooves in the injection-molded box as claimed in the invention extend substantially across the width of the bottom wall. Such an arrangement provides an optimum contribution to the load-bearing capacity of the reinforcing structure.

With particular preference, the ribs and grooves of the injection-molded box as claimed in the invention are in such an alternating arrangement with respect to each other that the individual ribs do not directly adjoin each other and that the individual grooves do not directly adjoin each other. It has been found that this further assists good demolding, since there is a significant risk of poor demolding at the location of adjoining grooves and/or ribs. With strong preference, the invention relates to an injection-molded box, wherein the reinforcing structure is configured as a corrugated sheet. A corrugated sheet is an elegant embodiment which satisfies the preferred characteristics which have already been mentioned above. In this case, a corrugated relief can readily be manufactured by means of injection-molding, can be dcmoldcd from the respective molds and has good reinforcing properties.

Preferably, the corrugated sheet comprises ribs which have been leveled in the horizontal direction on the underside. This is advantageous, inter alia, for moving the box during transportation.

Preferably, in the corrugated sheet, the peaks and troughs are of a leveled design in the horizontal direction, so that the inner side and the outer side have an increased flat contact area.

The plastic of the injection-molded box as claimed in the invention preferably comprises an impact modifier as an additive, which impact modifier preferably comprises polyhydroxyalkanoate (PHA) or polybutyrate adipate terephthalate (PBAT).

Tn this case, PHA is particularly preferred, as this can be considered to be a bio- based plastic and is therefore less environmentally polluting.

Due to the impact modifier, the strength of the box is increased for the intended application. Cured polylactic acid is inherently very stiff and may be brittle as a result; the impact modifier decreases this fragility. A useful content of impact modifier in the plastic is between 10 and 30% by weight.

In addition, it is advantageous if the plastic of the injection-molded box as claimed in the invention comprises fiber material as an additive, for example jute or hemp. The fiber material furthers the degradation of the plastic, both in the case of a burial and a cremation. In the case of a cremation, the fiber contributes to complete incineration of the coffin. With general preference, the fiber material used is of plant origin. A useful content of fiber material in the plastic is between 10 and 40% by weight. A higher fiber material, up to approximately 60% by weight also forms part of the invention and offers the advantage that the cost price of the plastic is reduced. In order to provide the plastic of the injection-molded box as claimed in the invention with a color, preferably natural colors are admixed to the plastic, such as for example indigo, turmeric and madder. Preferably, the injection-molded box as claimed in the invention comprises a detachable lid which is coupleable to the upright walls of the box at the top side thereof, so that the contents of the box are closed off.

In this case, it is particularly preferred if the lid comprises a top wall which is provided with a reinforcing structure produced by making a portion of the top wall thicker and/or is provided with a reinforcing structure as indicated above with respect to the bottom wall of the box.

The lid, for example, is made of the same material as the box. The lid is also preferably provided with a reinforcing structure, although the intended load-bearing capacity may be less than 120 kg, for example 100 kg or less. The thickness of the lid may be, for example 4 mm, with the reinforcing structure having a thickness of 6 mm.

The lid is coupleable to the box by means of coupling features which are preferably provided both on the short side and the long side of the box and the lid. The coupling features are configured, for example, as protruding ribs on opposite edges of the lid and box. When the lid is placed on the box, these protruding ribs adjoin one another in pairs. In order to close the lid on the box, a separate, sleeve-like body is slid over each pair of protruding ribs, so that the pair is held together united.

Preferably, the box as claimed in the invention is provided with a carrier edge which extends along the periphery of the bottom wall. This improves the ease of handling of the box, in particular during funerals. Preferably, the carrier edge comprises an indented profile into which a person can place the fingers of his hand.

Furthermore, it is preferable if a beveled edge with transverse grooves is provided between each of the long side walls and the bottom wall of the injection-molded box as claimed in the invention. Such grooves serve to guide ropes which are used when the coffin is being lowered into a grave by hand or by motor. Preferably, the grooves are provided at three locations on the beveled edge, that is at the front, in the center and at the rear. Between the grooves, the edge has a leveled profile in the horizontal direction. As claimed in a second aspect, the invention relates to a method for injection-molding a box, preferably suitable as a coffin, which is made from a plastic which comprises a bio-based plastic as its main component, wherein the bio-based plastic comprises polylactic acid,

wherein the box comprises a bottom wall and upright walls connected thereto, and wherein the bottom wall is provided with a reinforcing structure,

comprising the following steps:

manufacturing an injection mold comprising an upper mold and a bottom mold, shaped according to the dimensions and the design of the box;

introducing the plastic into the injection mold in a plastic state;

allowing the plastic to cool;

opening the injection mold;

removing the injection-molded plastic box;

wherein the injection mold is shaped in such a way that the following is true for the box obtained by means of the method:

the opposite adjacent walls within the reinforcing structure satisfy a modified release angle of at least 3 degrees, preferably at least 6 degrees, and most preferably at least 10 degrees.

This method provides a way to produce such a box from bio-based plastic by injection- molding which can readily be removed from the injection mold.

With the method as claimed in the invention, it is preferred if the box obtained by injection-molding complies with one or more of the same measures as the injection- molded box as claimed in the first aspect of the invention.

As claimed in a special preferred embodiment of the method as claimed in the invention, the reinforcing structure is configured as a corrugated sheet. The injection-molding is preferably carried out as claimed in the method of cascade injection-molding, in which the mold is filled with plastic material having a temperature of between 150 and 190°C in 30 to 90 seconds. During injection, the temperature of the mold is approximately 160°C and it is cooled to 40°C in approximately 2 to 3 minutes, after which the molded structure is demolded. The invention will be explained in more detail below with reference to the attached drawings, in which:

Fig. 1 shows a perspective view of a preferred embodiment of the box as claimed in the invention;

Fig. 2 shows a bottom view of the box as claimed in the invention illustrated in Fig. 1;

Fig. 3 shows a cross section in the longitudinal direction of the box as claimed in the invention illustrated in Fig. 1;

- Fig. 4 shows a detailed and perspective view of a cross section of a corner of the box as claimed in the invention illustrated in Fig. 1;

Fig. 5 shows a cross section of a coupling feature at the edge of a lid and a box as claimed in the invention;

Fig. 6 shows a perspective view of the underside of the box as claimed in the invention.

In the figures, identical parts are denoted by the same reference numerals.

Fig. 1 shows a coffin 1 with a detached, coupleable lid 3. The lid 3 is coupleable to the upright walls 5, 7 on the top side of the box by means of the side walls 9, 11. By means of the interacting coupling means 15 and 13, the lid 3 can be coupled to the box in a closing manner by joining the coupling means using a slidable sleeve part 17. The lid has a top cover 10, provided with a reinforcing structure (not shown). Fig. 2 shows the bottom wall 20 of the box 1 from Fig. 1, viewed from below. Along the width of the bottom wall, elongate elevated portions extend as ribs 24 and recessed portions as grooves 22, in alternating sequence and in a parallel connection with one another. The combination of ribs and grooves thus forms a corrugated relief which may be regarded as a corrugated sheet and which serves as a reinforcing structure for the bottom wall.

In addition, the underside of the box is provided with a carrier edge 26 which extends along the entire periphery of the bottom wall 20. Fig. 3 shows a cross section in the longitudinal direction of the box from Fig. 1 which shows the corrugated relief of that part of the bottom wall which is configured as a corrugated sheet with alternating ribs 24 and grooves 22. In this case, the troughs of grooves 22 are leveled in the horizontal direction and the same applies to the peaks of the ribs 24. The upright wall parts 40, 42 of the ribs and the grooves arc each at a release angle of approximately 10 degrees. The transition of the leveled portions of ribs and grooves to the upright wall parts 40, 42 of the ribs and the grooves is rounded. The carrier edge 26 comprises an indented profile into which the fingers can be placed in order to lift the box off the ground. The figure shows the lower adjacent part of the side wall 5.

Fig. 4 shows a detailed and perspective view of a cross section of a corner of the box as claimed in the invention illustrated in Fig. 1. The opposite walls 40 of the elevated portion 24 are at an angle of approximately 20 degrees to each other, so that each wall has a release angle of 10 degrees. The opposite walls 42 of a recessed portion 22 are at an angle of likewise approximately 20 degrees to each other. The same angle is present between the walls 44 which form the indented part of the carrier edge 26. Likewise, the wall 46 is at a release angle to the side wall 5. The figure shows the lower, adjacent part of the side wall 5. The illustrated structures of the box thus meet at the modified release angle as claimed in the invention, as a result of which the box - and in particular the reinforcing structure thereof - is readily releasable when it is made from a plastic which is biodegradable. The rounded transitions between the upright wall parts 40, 42 and the horizontally leveled peaks and troughs, as well as the alternating connection between ribs and grooves, contribute further to a good releasability of the box as claimed in the invention.

Fig. 5 shows the adjoining edges of a lid 11 and box 7 which have been connected to each other, which edges are provided with coupling features 13 and 15, respectively, which are in the shape of a protruding profile. The two adjoining profiles mate with each other and are held together by a sleeve 17 which is slid laterally across the profiles. If desired, the sleeve 17 may also be removed by sliding in order to remove the lid from the box. Fig. 6 shows the underside of the box 1 as claimed in the invention in perspective, with the bottom wall 20 having a beveled edge 60 with the visible side wall 7. The opposite side wall also has a beveled edge 60 with the bottom wall 20. Four adjacent transverse grooves 62 are provided at three different locations on the beveled edges 60. These grooves act as a guide for ropes by means of which a coffin is lowered into a grave by hand.

Claims

1. An injection-molded box, preferably suitable as a coffin, comprising a bottom wall and upright walls connected to the latter, which is made from a plastic which comprises a bio-based plastic as its main component, wherein the bio-based plastic preferably comprises polylactic acid, and wherein the bottom wall is provided with a reinforcing structure,

characterized in that the design of the reinforcing structure is such that adjacent walls within the reinforcing structure satisfy a modified release angle of at least 3 degrees, preferably at least 6 degrees, and most preferably at least 10 degrees.

2. The injection-molded box as claimed in claim 1, wherein the reinforcing structure comprises elevated portions and recessed portions which are configured as elongate ribs and elongate grooves, respectively.

3. The injection-molded box as claimed in claim 1 or 2, wherein the ribs and grooves are rounded.

4. The injection-molded box as claimed in claim 3, wherein the ribs and grooves extend substantially across the width of the bottom wall.

5. The injection-molded box as claimed in claim 3 or 4, wherein the ribs and grooves are in such an alternating arrangement with respect to each other that the individual ribs do not directly adjoin each other and that the individual grooves do not directly adjoin each other.

6. The injection-molded box as claimed in any of the preceding claims, wherein the reinforcing structure is configured as a corrugated sheet, preferably, the corrugated sheet comprises ribs which have been leveled in the horizontal direction on the underside.

7. The injection-molded box as claimed in any of the preceding claims, wherein the plastic from which the box is made is biodegradable.

8. The injection-molded box as claimed in any of the preceding claims, wherein the plastic comprises an impact modifier as an additive, which impact modifier preferably comprises polyhydroxyalkanoate (PHA) or polybutyrate adipate terephthalate (PBAT).

9. The injection-molded box as claimed in any of the preceding claims, wherein the plastic comprises fiber material as an additive, for example jute.

10. The injection-molded box as claimed in any of the preceding claims, provided with a detachable lid which is coupleable to the upright walls of the box at the top side thereof, so that the contents of the box are closed off.

11. The injection-molded box as claimed in claim 9, wherein the lid comprises a top wall which is provided with a reinforcing structure produced by making a portion of the top wall thicker and/or is provided with a reinforcing structure as indicated in claims 1- 8.

12. The injection-molded box as claimed in any of the preceding claims, the underside of which is provided with a carrier edge which extends along the periphery of the bottom wall.

13. A method for injection- molding a box, preferably suitable as a coffin, which is made from a plastic which comprises a bio-based plastic as its main component, wherein the bio-based plastic comprises polylactic acid,

comprising the following steps:

introducing the plastic into the injection mold in a plastic state;

- allowing the plastic to cool;

opening the injection mold;

removing the injection-molded plastic box;

wherein the injection mold is shaped in such a way that the following is true for the box obtained by means of the method: the adjacent walls within the reinforcing structure satisfies a modified release angle of at least 3 degrees, preferably at least 6 degrees, and most preferably at least 10 degrees.

14. The method as claimed in claim 13, wherein the box obtained by injection- molding complies with one or more of the same measures as the injection-molded box as claimed in claims 1-12.