Note: Descriptions are shown in the official language in which they were submitted.
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~ackground of the Invention
Various devices are known for holding a plurality
of containers together. In general, the containers should
be held tightly together whilst not being allowed to come
into actual contact. In one instance, a bottle combining
unit holding four or six bottles of beer in a firm state
has been made using cardboard overwraps. In another
instance (see for exa~ple U.S. 3 733 100), unorientated
plastics sheet material has had circular openings punched
into it for receiving and gripping beer cans; the openings'
margins lip up with localised stretching thereof.
U.K. 982 036 and U.S. 3 386 876 do not relate to
holding containers together, but disclose a uniaxially
and biaxially orientated mesh structures. Although the
openings in the biaxially orientated structure are roughly
square, the openings in the uniaxially orientated structure
are oblong and too long conveniently to hold the normal
circular section bottles or cans.
~he verb "orientate" as used herein means "molecu-
larl~ orientate" and derived words such as "unorientatedl'
and "orientated" have equivalent meanin5s.The Invention
According to the invention, the containers are held
together by a~ integral piece o~ plastics material having
generally quadrilateral openings each having its sides
defined by a pair of orientated first strips under tension
which have substan-tial elasticity and which will have twisted
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so that their centre parts lie flat against the container,
and a pair of second strips which are not subs-tantially
elastic. ~he holding device, which is the piece of
plastics material, also ~orms part of the invention.
Using the invention, the containers can be held
together very ~irmly but prevented from touching each
other at the location of the device. It has been found
that the generally quadrilateral openings and the strips
~which will be wider than the~ are thick) can cause the
majori~y or almost all of the plastics material of the
device to be put under tension and stretched elastically
at least to some extent (though some plastic deformation
may also occur) when the containers are inserted,
provided the openings are correctly sized. Thus when
the device is forced over the containers, the elastic
strips are easily deformed to fit snugly around the
container and two ;opposite strips will twist so that
their centre parts lie flat against the container
(instead of merel~ lipping up). It is believed advant-
ageous to avoid orientating two opposite sides of the
openin~ because the unorientated plastics material gives
added stability to the eventual pack. Whsn the devices
are in the form o~ a contlnuous band, the procedure can
be ~acilitated by putting the band u~der longitudinal
tension and the longitudinal strips will take up the
curvature of the container sides and whilst doing so
apply tension to the transverse strips, which may
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themselves be subjected to very little extension.
It is stated herein that certain of the strips
have substantial elasticity~ This means that when
they are stretched to a small extent, e.g. to produce
an exte~sion of the order of 9~, and held stretched to
that extent, a substantial or high force must be
applied and continue to be applied. Considerable
plastic (i.e. non-elastic) deformation is tolerable
as long as sufficient elastic deformation also occurs.
~urthermore the elastic force applied after extension
has occurred may decrease somewhat. ~he intention
is that the elastic force applied by the strips should
hold the pack of containers rigidly together when the
containers have beèn inserted in the openings. The
plastics material must be chosen accordingl~.
Although the elasticity of plastics material,
both unorientated and orientated, varies significantly
from material to materia~ these properties are easily
ascertainable. It is found that a low density poly-
ethylene such as "Sclair" (~rade Mark), manufacturedby Du Pont of Ca~ada, is suitable and exhibits better
elastic properties after orientation than it does
be~ore orientation.
The plastics material device can be of light
weight and of very low cost. ~he low cost enables
two such devices to be used without excessive
expenditure; for instance in the case of beer bot~les,
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one device can be towards the top of the bottles and
the other towards the base. ~owever it would be possible
to use just one device in suitable circumstances, for
instance when holding beer cans~-together.
~he device of the invention can be made b~
uniaxially stretching a starting material having a
pattern of holes or depressions
. ~he starting material is preferably not
orientated, though melt orientation may have occurred.
If the initial holes are formed by punching, the punched-
out pieces are smaller than the~ would be if the
de~ice were formed b~ direct punching of pre- -
orientated material, and the punched-out pieces are
not orientated, which facilitates both punching and
reclaiming the plastics material. Theoretical
considerations and further details such as possible
~t shapes of the holes or depressions are gi~en in copending~
Application ~ b~'the present Applicant, filed October gth
1979 under the title "Plastics Material Mesh Structure".
~he starting sheet material can be of an~
thickness, including low thicknesses which are normally
referred to as films; furthermore, though -the sheet
materiai is~ preferably planar on each ~ace, this
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is not necessarily so. If depressions, rather than holes, are
formed in the starting material for the method, the depressions
must be such that they rupture when the material is stretched.
The strips need not be parallel-sided, though substantial-
ly parallel-sided strips are preferred.
Description of Preferred Embodiments.
~he invention will be further described, by way of example,
with reference to the accompanying drawings, in whicho-
~igure 1 is a plan view of part of some starting material
for a method in accordance with the invention;
~igure 2 is a plan view of part of a band of container
holding devices in accordance with the invention, the positions
of the containers being indicated;
~igure 3 is a plan view of container packs made using the
devices of ~igure 2;
Figure 4 is a plan view of the packs of ~igure ~;
Figure 5 is a plan view of part of another band of
container holding devices in accordance with the invention;
Figure 6 is a schematic plan view of apparatus for applying
the device of the invention to containers; and
Figure 7 is a schematic side view of the apparatus of
~igure 6.
~hough many different plastics materials and different
thicknesses can be used, the starting material 1 shown in
~igure 1 can be of low density polyethylene (say 0.918 gm/cc.)
and have a thickness of about 0.5 mm. The starting plastics
material can have some elasticity, and is preferably un-
orientated. As can be seen, the plastics sheet material
has groups of four main holes 2 whose
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centres are on a rectangular grid. The main holes 2 are long-shaped
with their major axes at right angles to the longitudinal or machine
direction, which runs across the page. In the transverse direction,
there is a further hole 3 between each pair of main holes 2, and its
transverse dimension is substantially less than that of the main holes
2. ~Each group of main holes 2 is separated from the next group by
holes or (as shown) slits 4 which have circular holes at each end
to prevent splitting. In general, the holes or slits 4 should be
long-shaped with their major axes in the transverse direction. The
holes or slits 2, 3 and 4 can be formed by punching or in any other
suitable manner, or could be merely depressions.
The sheet material 1 is in the form of a long band, and
the band is stretched in the machine direction (indicated by the double-
headed arrcw in Figure 1) in any suitable manner. In practice, the
stretching can be effected in a hot water bath using differential
speed rolls. The stretch ratio can be chosen in accordance with the
plastic used and the strength required, but sultable stretch ratios
are for instance between 1:5 and 1:8, as measured across the holes,
i.e. comparing the dimension a in Figure 1 with the dimension A in
Figure 2. During this stretching, the zones at the sides of the holes
2, 3 are orientated and drawn into longitudinal strips 5. For clarity,
these zones are shown cross-hatched in Figure 1. It will be seen
that the zones between the slit-shaped holes 4 and on the outside
of the slit-shaped holes 4 are not stretched.
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Looking at Figure 2, which shows the stretched band, the
band is formed of an integral succession of devices 6 for holding
a plurality of containers together. In the ins~ance shcwn, four
containers are to be held together, but it can be seen that with simple
¦ 5 modification, two oontainers or six containers or other suitable
¦ numbers could be held together. The devices 6 are joined to each
other ky parts 7 in the line of the slits 4.
In each device there is a plurality of generally quadrilateral
openings 8 on a rectangular or square grid, which have been formed
from the main holes 2 and which are for receiving and gripping the
respective containers, shown as squat beer bottles 9 in Figure 3.
As can be seen in Figure 2, each opening 8 has its sides formed by
strips, the longitudinal strips S being orientated along their length
and the transverse strips 10 not being substantially orientated.
The longitudinal strips 5 are substantially longer than the transverse
strips 10. In Figure 2, the hatching indicates where the thickness
of the plastic increases on passing from orientated plastic to unorientated
plastic, and the hatching lines run up the slcpe. It will be seen
that the orientated strips 5 of one opening are aligned with the
orlentated strips 5 of the next opening and that the orientation passes
from the end of one strip into the end of the aligned strip, in the
same device 6. Furthenmore, the orientation of the strips 5 continues
beyond the corners of the open mgs 8. Orientation itself increases
the s~rength of the plastic, and by continuing the orientation beyond
the corners of the openings 8 the transition between the orientated
plastic and the unorientated plastic is strengthened.
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It will be seen that the orientated, longitudinal strips
5 give the band shown in Figure 2 significant strength in the machine
direction and also give the sides of the openings 8 good elastic
properties. Due to their greater bulk, the unorientated, transverse
strips 10 stop the bottles 9 contacting each other and clinking.
The sizes of the openings 8 are such that some elastic stretching
of the sides is required in order to receive the bottles 9. In general,
it is believed that the longitudinal strips 5 should be extended b~
2 or 3% up to 15% on inserting the bottles 9, a preferred range being
5% to 10%. The force required to hold the strips 5 so extended is
a force of the order of 1 Kg wt., eg. 0O4 up to 2 Kg wt.
In theory, it w~uld be possible to form the band shown
in Figure 2 by suitable formation of the initial holes and stretching
the plastics material in two directions at right angles, either
simultaneously or sequentially. This however is not preferred because
it would be more difficult to produce accurately-sized openings 8
and because the transverse stretching would be expensive.
In order to pack the bottles 9, the bottles 9 are two-by-two,
e.g. touching one another along a conveyor. The devices 6 are provided
in the form of a continuously-moving band which is under longitudinal
tension, and which can came from a roll; the band is pressed down
over the tops of the bottles 9 to grip the bcdies of the bottles 9.
Figure 2 generally indicates the positions of the bottles 9, before
pressing the band down. Either subsequently :-or si~multaneousl~ a
- second band ca~ be pressed o~er the bottles 9'1 to grip the
25 bodies of the- bot1;les 9 ~t a posi;ti~n s~ced ~r~m the
~st b~do The shape of the bottles 9 shown in Figure
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3 makes it more desirable to push both bands on from the top because
the relatively small diameter at the neck of the bottle 9 facilitates
entry into the openings 8 of the device, and in this case both bands
can be identical. However, in other cases, it may be preferred to
push one band on frcm the top and the other band frcm the bottcm.
In this latter case, it may be necessary to have the cpenings 8 in
the lcwer band somewhat larger because it may be m~re difficult to
force the lower band over the bottles as there is no tapered section
to facilitate entry.
As shown in Figures 3 and 4, the longitudinal strips 5
twist round so that the centre part of each strip lies flat against
the sides of the container. For this reason, there are two spaced,
parallel strips 5 in the centre zone, though Figure 5 shows that a
single central strip 5 can be used, if desired, and the single strip
5 ~Yill twist round.
Preferably, the outer strips 5 have to stretch to a greater
extent than the inner strips 5, to hold the pack firmly together with
pairs of bottles 9 pulled towards each other and merely separated
by the thickness of the two strips 5 (or just one strip 5 in the
Figure 5 device). To arrange this, the centres of the bottles 9 are
slightly outside the centres of the original openings 8.
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~ y lying flat against the sides of the bottles 9, the stripsS hold the bottles 9 more firmly than they would if they were on
their edges, and in addition the major part of the material of the
band is stretched elastically; in practice one can stretch all the
material excep~ that at the corners of the device and at the inter-
sections of the longitudinal strips 5 and transverse strips lO.
Figure 4 s~cws a gap at the inner corners of each opening 8 but not
at the outer corners, and this is preferred. However, there could
also be gaps at the outer corners or alternatively no gaps at all.
The individual packs can subsequently be parted by slitting along
the parts 7. In the final pack, all the strips 5, lO are under tension
in the direction of their length.
If desired, a U-fold (not shown) can be formed in the central
longitudinal strip 5 in Figure 5 to provide a greater thickness of
material between adjacent bottles 9.
m e strips lO adjacent the slits 4 could be longer, to
fonm handles for holding the packs or tags for carrying advertising
matter.
Example
In general this Example is a typical example for a starting
material made of extruded, unorientated "Sclair" having a unifonm
thickness of 0.5 mm. All distances are in mm and all forces are in
Kg. wt.
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.Outer strip~ . Inner Strips.
. 5 5
.Strip width before stretchin~-~distance- s
.between edges of holes 2 and 3 in
Figure 1) . 9.5 . 6.4
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Strip width after stretching . .
tat narrowest p~int) . 4.8 0 3.2
.
.Strip thickness after stretching 0.18 . 0.20
.Strip length ~efore stretching
S(a in Figure 1)
-- ;
sStrip length after stretching
(A in Figure 2) 5008 '
.Stretch ratio . 5.3:1
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.Static force required to produce .
,5~ extension . 0.75 '. 0.5
. .
sStatic force required to produce ..
s : : :
.10% extension 1.4 1.0
isStatic force required to produce . .
S15~ extension s 1.75 1.5
s _ _ . s
m e forces noted above dropped by a value of frcn 0.1 to 0.15
Kg wt. on holding the strips 5 extended.
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he Ap~aratus~
~he copending application discloses apparatus for making
the devices of the invention. The devices, in band form, are
applied as shown in Figures 6 and 7r
The bottles 9 are supported on their sides by cradles
11 carrie~ on continuously-moving horizontal conveyorS12.
Two bands of devices 6 are led at the same speed as the
conveyor 12 from rolls(16) , along either side of the
bottles 9. Vertical rods 13; also moving at the same speed as
the conveyor 12, are carried on chains 14. The rods 13
gradually approach a position in which the devices 6 are
properly applied to the bottles 9, thereby pressing the devices
6 into their correat positio~. If necessary, the bottles 9 can
be ~lamped- to prevent them slipping sideways. The packs are then
cut from one another by a cutter indicated schematically at 15.
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