[0001] This invention relates to light-weight packages comprising skeletal containers.
[0002] It is known to make crates from thermoplastics materials, but such crates need to
have thick walls and/or thick reinforcing ribs if they are to be rigid enough for
use in transporting soft articles such as fruit and in particular tomatoes. Thick
walls and ribs mean that a large volume of thermoplastics material is consumed in
making the crate with the result that the crates are heavy and expensive and cannot
compete with crates made from compressed paper or low quality wood which are conventionally
used by fruit packers. German patent specification 1171812 discloses a package for
soft fruit, the package comprising a framework of interconnecting ribs held in tension
by an endless net. Endless nets usually require special heat-sealing or stitching
machinery to fit them around a framework and so are not suitable for fitting by hand
by unskilled horticultural workers in the field or greenhouse.
[0003] This invention provides a rigid light-weight package comprising a skeletal container
formed from a plurality of interconnected self-supporting ribs on which a compressive
force is exerted by a sheet material characterised in that:
a) the interconnected self-supporting ribs consist of thermoplastics material,
b) the total volume of the thermoplastics material used to make the ribs does not
exceed 3% of the capacity of the container, and
c) the sheet material has two ends and an intervening portion, one end of the sheet
being positively secured to a rib of the container, the intervening portion of the
sheet being stretched around the container so as to exert the compressive force on
the container and the other end of the sheet also being positively secured to a rib
of the container so as to maintain tension in the sheet material.
[0004] Preferably the containers have a capacity of from 500 to 100,000 cm
3 (especially 1000 to 14,000 cm3
).
[0005] The sheet material may be any material which is resilient and flexible enough to
be stretched around the container and which is strong enough (preferably even when
wet) to sustain a tension which exerts a compressive force on the container. The sheet
material may therefore be a woven cloth, a thermoplastics film (especially polyethylene
or polyolefin films) or a net (especially a polyethylene or polypropylene net). Nets
have the advantage of allowing easy circulation of air into and out of the package.
[0006] Positive means are provided to secure the ends of the sheet material to the ribs
of the container. For example, the positive means may comprise a layer of adhesive
(preferably impact adhesive) which bonds the end of the sheet material either directly
onto a rib or indirectly, that is to say the end may be bonded onto a member which
is itself fixed to the rib. Alternatively, the adhesive may be replaced by a clip,
preferably a clip which makes a tight snap-action fit around the rib. A third possible
positive means comprises a series of projections provided on the rib and preferably
moulded integrally with the rib. The ends of the sheet material are impaled upon the
projections (if the sheet material is continuous) or hooked over the projections (if
the sheet material is a net). The projections may be barbed to hinder accidental removal
of the sheet material or they may be swaged down onto the sheet material for example
using the technique known as ultrasonic staking or by pressing with a hot tool. Barbed
projections have the advantage of being simple to use and also being re-usable whereas
swaged projections provide a more permanent fastening which makes pilfering more difficult.
[0007] The containers and sheet materials are preferably made from aliphatic crystalline
polyolefins such as low or high density polyethylene or homopolymers of propylene
or copolymers of propylene with from 1 to 20% by weight of ethylene. The copolymers
are preferably made by introducing ethylene into the final stages of an otherwise
propylene homopolymerisation process. As an alternative to the copolymers there may
be used a homopolymer of propylene blended with up to 10% by weight of a rubber. Suitable
rubbers include butyl rubbers, polyisoprenes and the rubbery copolymers of ethylene
with 30 to 70% by weight (based on the ethylene) of propylene and optionally up to
8% by weight (based on the weight of the ethylene) of a non-conjugated diene.
[0008] The preferred aliphatic crystalline polyolefins preferably have a melt flow index
of from 0.5 to 40 g/10 minutes when measured according to British Standard 2782: Part
1/105C/1970 using a 2.16 kg load and carried out at 230°C in the case of predominantly
propylene polymers and at 190°C for all other polyolefins.
[0009] A preferred embodiment of the invention will now be described with reference to the
drawings in which:
Fig. 1 shows a side elevation of a container used to make a package according to this
invention.
Fig. 2 shows an end elevation of the container shown in Fig. 1.
Fig. 3 shows a plan view of the base of the container shown in Fig. 1 and 2.
Fig. 4 shows on a larger scale a section taken on the line A-A of Fig. 1 or 2 or E-E
of Fig. 1.
Fig. 5 shows a section taken on the line C-C of Fig. 3.
Fig. 6 shows a section taken on the line D-D of Fig. 1.
Fig. 7 shows a section taken on the line B-B of Fig. 3.
Fig. 8 to 10 show on an even larger scale modifications to the section taken on the
line A-A of Fig. 1 (as shown in Fig. 4).
Fig.11 shows a package incorporating the container shown in Fig. 1 to 3.
Fig. 1, 2 and 3 show a light-weight container 1 suitable for use in a package 2 as
shown in Fig. 11. Container 1 comprises opposed longitudinal walls defined by horizontal
longitudinal ribs 3 and 4 and uprights 5 and also end walls defined by uprights 5
and horizontal transverse ribs 7 and 8. Ribs 3 and 4 and ribs 7 and 8 are reinforced
by braces 6. The base of container 1 is defined by longitudinal ribs 4 and transverse
ribs 8 reinforced by cross-braces 9a and 9b. Feet 10 are provided at each corner of
the base to assist in aligning the base of a stacked container with the top of the
container beneath.
[0010] Ribs 3 and 7 and ribs 4 and 8 have sections as shown in Fig. 4 and 5 respectively.
Uprights 5 have horizontal sections as shown in Fig. 6 and are provided with horizontal
reinforcing flanges 11. Braces 6 have a horizontal section which is the same as the
vertical section of ribs 3 as shown in Fig. 4. Cross-braces 9a and 9b have vertical
sections as shown in Fig. 7.
[0011] Container 1 is used to form package 2 as shown in Fig. 11. Package 2 consists of
net 12 stretched around container 1. The ends 13 and 14 of net 12 are securely clipped
onto longitudinal rib 3 by a snap-action clip 14. Net 12 is clipped onto rib 3 in
such a way as to ensure net 12 is in tension so that it exerts a compressive force
on container 1.
[0012] It has been found that provided net 12 exerts a compressive force on container 1,
the package 2 has sufficient rigidity for it to be used in the transport of tomatoes
15 even though the total volume of thermoplastics material used in making the container
is less than 3% of the capacity of the package.
[0013] Fig. 8 shows an alternative method of securing net 12 to rib 3. Rib 3 is provided
with an integral barbed projection 20 onto which net 12 is hooked.
[0014] Fig. 9 and 10 show a further alternative method of securing net 12 onto rib 3. Rib
3 is provided with an integral projection 21 over which net 12 is hooked. Projection
21 is then swaged down onto net 12 using an ultrasonic or heat-staking technique so
as to produce a mushroomed stake 22.
[0015] Clearly the sheet wrapping material should be long enough to wrap around the container
and wide enough to enclose at least a major part (preferably at least 95%) of those
faces of the container around which it is wrapped. More preferably the sheet wrapping
material should be wide enough to alow its longitudinal edges to be folded inwardly
of the package to protect the remaining faces of the container.
1. A rigid light-weight package comprising a skeletal container (1) formed from a
plurality of interconnected self-supporting ribs on which a compressive force is exerted
by a sheet material (12) characterised in that:
a) the interconnected self-supporting ribs consist of thermoplastics material,
b) the total volume of the thermoplastics material used to make the ribs does not
exceed 3% of the capacity of the container, and
c)the sheet material (12) has two ends (13, 14) and an intervening portion, one end
of the sheet being positively secured to a rib of the container, the intervening portion
of the sheet being stretched around the container so as to exert the compressive force
on the container and the other end of the sheet also being positively secured to a
rib of the container so as to maintain tension in the sheet material.
2. A package according to claim 1 wherein the sheet material is positively secured
to a rib by means of a clip.
3. A package according to claim 2 wherein the clip is a snap-action clip.
4. A package according to claim 1 wherein the sheet material is positively secured
to a rib by being impaled onto a series of projections provided on the rib.
5. A package according to claim 4 wherein the ends of the projections are swaged down
onto the impaled sheet material to provide a more per- manentfastening.
1. Steife Leicht-Verpackung, bestehend aus einem in Skelettbauweise aus einer Vielzahl
von miteinander verbundenen, selbsttragenden Rippen aus thermoplastischem Material
gebildeten Behälter (1), wobei auf die Rippen durch ein flächiges Material (12) eine
Druckkraft ausgeübt wird, dadurch gekennzeichnet,
a) dass die miteinander verbundenen, selbsttragenden Rippen aus einem thermoplastischen
Material bestehen,
b) dass das Gesamtvolumen des zur Herstellung der Rippen eingesetzten, thermoplastischen
Materials 3% des Fassungsvermögens des Behälters nicht überschreitet und
c) dass das flächige Material (12) zwei Enden (13, 14) und einen Zwischenabschnitt
aufweist, wobei das eine Ende des flächigen Materials sicher an einer Rippe des Behälters
befestigt ist, wobei der Zwischenabschnitt des flächigen Materials um den Behälter
herumgestreckt ist, wodurch auf den Behälter die Druckkraft ausgeübt wird, und wobei
auch das andere Ende des flächigen Materials sicher an einer Rippe des Behälters befestigt
ist, damit die Spannung in dem flächigen Material aufrechterhalten wird.
2. Leicht-Verpackung nach Anspruch 1, dadurch gekennzeichnet, dass das flächige Material
durch eine Klammer sicher an einer Rippe befestigbar ist.
3. Leicht-Verpackung nach Anspruch 2, gekennzeichnet durch eine Klammer mit Schnappwirkung.
4. Leicht-Verpackung nach Anspruch 1, dadürch gekeniizeicEiriet; dass das flächige
Material durch Aufstecken auf eine Reihe von Vorsprüngen, die auf einer Rippe vorgesehen
sind, sicher an der Rippe befestigbar ist.
5. Leicht-Verpackung nach Anspruch 4, dadurch gekennzeichnet, dass die Enden der Vorsprünge
zur haltbareren Befestigung auf das aufgesteckte, flächige Material aufgestaucht sind.
1. Emballage léger rigide comprenant une caisse à claire-voie (1) formée de plusieurs
nervures se passant de support et interconnectées sur lesquelles une force de compression
est exercée par une matière en feuille (12), caractérisé en ce que:
a) les nervures se passant de support et interconnectées sont faites d'une matière
thermoplastique;
b) le volume total de matière thermoplastique utilisée pour la fabrication des nervures
n'excède pas 3% de la capacité de la caisse, et
c) la matière en feuille (12) présente deux extrémités (13, 14) et une partie intermédiaire,
l'une des extrémités de la feuille étant fixée fermement à une nervure de la caisse,
la partie intermédiaire de la feuille étant étirée autour de la caisse, de manière
à exercer la force de compression sur celle-ci, et l'autre extrémité de la feuille
étant aussi fermement fixée à une nervure de la caisse, de manière à maintenir la
matière en feuille tendue.
2. Emballage suivant la revendication 1, caractérisé en ce que la matière en feuille
est fermement fixée à une nervure au moyen d'une pince.
3. Emballage suivant la revendication 2, caractérisé en ce que la pince est une pince
à emboîtement élastique.
4. Emballage suivant la revendication 1, caractérisé en ce que la matière en feuille
est fermement fixée à une nervure par le fait qu'elle est accrochée sur une série
de saillies prévues sur la nervure.
5. Emballage suivant la revendication 4, caractérisé en ce que les extrémités des
saillies sont rabattues sur la matière en feuille accrochée, afin d'assurer une fixation
plus permanente.