Note: Descriptions are shown in the official language in which they were submitted.
1~365~7
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This invention relates to containers suitable for,
and in the preferred case containing, carbonated beverages, such
containers being formed in thin walled plastics material and
which are nestable with other similar containers.
There has been much activity in research and develop-
ment which has been concerned with the production of a thermo-
plastic container which is suitable for holding carbonated
beverages such as beer or soft drinks. Heretofore, these beverages ~ . .
have largely been held in metal cans having seamed end caps,
some with ring-pull opening devices, or have been held in glass
bottles closed by scrcw closures or crown cap c:Losu.res. Mekal
cans and gla~s bottles have largely captured the carbonated bev-
erage markets princ.ipally because they have suf~ic.ient stren~th
to wi~hstand the super atmospher:ic pressures which exist :Ln
containers ~illed wi.th carboIIatecl beverclcJe and sealed. These
pressures furthermore increase depending upon the temperature
of the environment in which the containers are stored. Generally,
the higher the env.i.ronment.ternperature, the hi(3her the internal
pressure generated in the containe~s. Another reason for using
. metal and glass for these beverages is that these materials
are highly impermeable to moisture and air, and carbonated
beverages stored in containers of glass and meta- have a long ~ :
shelf life. .. .;
However, the use of glass and metal for these
containers does create some disadvantages. Firstly, it is
anticipated that the .costs of these mater.ials wi.ll increase
. faster in the future than plast.ics materials,
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and secondly energy conservationists Eeel that too much
energy is reguired to produce these containers, as
compared to the energy required to produce thermo-formed ~'
plastics containers. Glass bottles have the obvious "'~
disadvantage of being dangerous, and this also applies, ~;
perhaps to a lesser extent, to metal cans. Thus, there
is a real need for a plastics material container which
i8 suitable ~or holding carbonated beverages.
When a carbonated beverage is held in a plastics
material container, with the passage of time, and due '
to the internal pressure, t'he plastics material "creeps"
and it extends slig'htly. q~lis invariably has the e~ect
oE distor~ing the base o~ t'he container unevenly ~o that
1 it were Eree standing beEore commencement o~ ~he
"creep", it'becom~s tilted or what is known as "~ocker".
That is to say, the free standing ~tability of the
conta iner becomes seriously impa ired~ ;
The present invention is concerned with this
problem and seeks to provide a novel form of a base for
a plastics container which undergoes some creep when
filled with carbonated beverage and sealed, will never-
theless not become a "rocker". The inventio~ although
principally concerned with sealed containers for ''
carbonated beverages, is not totally limited thereto, ''
as clearly the novel base oE t'he invention can be used
in containers ~or holding other products which, in
particular circumstances, give rise to increased internal
pressure .
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Where the containers, however, are speciically
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1 -- designed to hold carbonated bever~ges, they may be such as to
present a gas barrier to the container contents such as to
prevent substantial loss of carbonation gas over a period of
storage, after the container has been sealed. With this
in mind, the plastics material may be in laminated form or be
coated internally so as to de~ine an outer case and an internal
liner which provides the gas barrier, the outer case providing
more of the strength of the container. The container can of
course be of a single thickness plastics material. In fact,
laminated containers may be formed as set forth in our
British Patent Nos. 1,232,473, 1,325,726 and 1,436,875.
The container may comprise an outer case of poly-
st~rene, pol~propylene, polyethylene or the like and the
lining material may be, for exampLe, h:igh barr:ier aaryl:Lc
material, polyvinyl chloride or copolymer thereof or a coating
material.
Contalners of the above mentioned general type are
known, and are generally filled with a carbonated beverage
and sealed by means of a lid. When such a container is initi-
all~ sealed, the beverage is usually chilled and thereforetends to retain the carbonating gas in solution. With the rise
in temperature of the beverage to ambient after sealing of the
container, the pressure inside the container increases due to
release of some of the carbonating gas from the beverage. The
plastics material container creeps as e~plained and such creep is
not objectionable, provided it does not produce a "rocker", but
of course any bursting of the container should be avoided.
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1 It is already known to construct a ~hin walleA plastics `
material container to give it the facility of controlled limited
expansion under an increase in gas pressure inside the container,
when sealed, and the known proposal comprises providing the ~.
container with a bottom having a spherically concave region which
can flex outwardly to spherically convex form when the pressure :.
inside the cont~iner exceeds a predeterm:ined maximum. Thi.s.
facility of increasing the effecti.ve volume of the container
does have the advantage of relieving the internal pressure and . :
thereby reducing the danger of the container exploding subsequent-
ly, but of course it produces a "rockerl' which :is unclesirab:Le~.
r.rhe present invention seeks to provide a thermoform~cl
container having a base configurAt:ion des.icJned to w.ithstand the
higher internal pressures without basica:Lly changing shape, such
as occurs in the Icnown containers and which is nestable wi.th
other similar containers.
~ ccording to a first aspect of the present invention,
there is provied a sealed, thin walled plastics material container
which has undergone creep due to an increased pressure wil:hin
the con-tainer, said container having a wall, and a base deined
by a central portion surrounded by spaced feet on which the
container is free standing, and strap portions which radiate . :.
from the central portion, extend between the feet and curve .
upwardly to the wall, said.strap porkions acting to constrain
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creep movement of the central portion so that it is prevented
from projecting through the plane containing the surfaces o~
the feet on which the container is free standi.ng.
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1 Preferably, the sai.d s-trap portions and control
portion of the base lie on and define in part spherical
surface.
sy such constructi.on, the base resi.stance to creep
i.g des.i.grled around a hemi.- or part spherical module, ~.
which has intlerent strenyth. Tlle ~eet give the base
free-standincJ stability.
Pre:ferab:Ly, in one arrangement each foot is ~ ~ .
gencral.ly ki~ney or bean-shaped i.n sect.ion and curves
round the sa:i.d central rccJi.on arld :i.t :is a:l.so preEerrecl
~hat ~he .inner edye of ~ach .eOo~ ha~ a c~ntral r~cos~.
'rhis recess on the .i.nside oE ~ach Eo~t provid~s additiona:L
resistance to the whole base yoing to spherical form
under the high internal pressu:re in the container.
Furthermore, th~ rigidity of the base is maintained.
In another arrangement, the feet may each be
generally trianyular in section, widening from the
central portion outwardly, and the opposed sides of
adjacent feet are substantially flat and close
together so that the strap portions are of narrow
width.
qlhe :i.nvention also prov.ides a contai.ner be~ore be:i.ng
filled and sealed.
rl`he sea.l.incJ rmay be by means oE a metal or plastic
cap, and the container top would be sui.tably Eormed
for the purpose. .
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1 Embodiments of the present invention will now . ::
be described, by way of example, with reference
to the accompanying drawings, wherein :-
Fiyure 1 is a perspective view of a container
accordlng to one embodiment of the invention
be~ore seaLirlcJ ~herec)E ;
Figure 2 is a side elevation of the container of
Fiyure 1 ;
Figure 3 i.s a pLan view of the container O;e Figure~
1. and 2;
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Figures 4 and 5 are enlarged framentary sectional
elevations, the sections being taken respectively , :
on lines Y-Y and Z Z oE Fiyure 3;
Figure 6 is an enlarged fragmen-tary view similar
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to Figure 4, but shows the con-tainer top after the
application of a sealing lid thereto; and
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Figures 7, 8 and 9 are respectively a perspective
view, a side elevation and a plan, similar to figures
1, 2 and 3, of a container accorcling to a second
embodiment of the invention; and
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Figures 10 and 11 are enlarged framentary sections,
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taken on l.ines A-~ ancl B-B oE figure 4, oE the base `.
oi the container shown in lgures 7, B snd 9.
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eferring to the drawings, the container shown
in Figs 1 to 6, is a thin walled, thermo-formed,
plastics mug or cup 10, having a principal frustro
conical wall portion 12 at the bottom of which is
provided a base 14 in accordance with one embodiment
of the invention, and at the top there is a de-nesting
ring 16. The de-nesting ring is shown in greater detail
in Figure 4, and it will be seen that at the top oE
this ring -there is a flat outwardly extending flange ,~
18. This flange 18 is for receiving an equivalent
Elange of a metal lid in the manner shown in Figure
6, the lid baing indicated by numeral 20. The
lid is double seamed to the flange 18 in order to
~orm an eEfective gas-tight seal therewith, and the
metal li~, which i~ oE conventional Eorm, i9 provided with
a ring-pull openiny dev.ice 22 for the purposes of
gaining access to the container contents, which in this
ca~e will be acarbonated beverage.
The container thus far described is known, apart
from the specific base construction illustrated in the
drawings which forrns the novel feature of this
embodiment of the invention.
Referring now in particular to Figures 1 to 3 and
Figure 5, it will be seen that the base 14 is designed
on the principle oE a hemi- or part spherical shape
or form illus~rated best by numer;al 30 in Figure 5.
The base would be completely of this hemi- or part
spherical form 30, apart from -the provision of three
equi-angularly arranged ~eet 32 which project downwardly
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l ` from the spherical form 30, and provide a means
whereby the container will be free-standing. The :.
feet 32 are arranyed around a pitched circle so as
to leave a central portion 34 which lies on the spherical
form, and radial strap portions 36, also lying on
thi.s spherlcal form, extend from and are integral
with the centra1 por-tion 34, these portions 36 curving
upwardly to the bottom oE the principal wall section
12.
.
The feet 32 each have a generally flat bottom 38
which lie i.n a common transverse plate relative to
the container axis, and each is generally lcidney or
bean~~haped in cross-section as w.i.ll be s~en clearl~
in Fi~ure 3. Becaus~ the ~eet extend Erom a
spherical module, the outer wa:lls of the feet are
longer than the inner walls. The outer walls 40
lie essentially on a Erusto-conical surface of the ~ ~:
same cone angle as the wall 12, whilst at the centre
of each of the inner walls 42 there is a recess 44 into
which the contr~ portion extends and which has the
effect of slightly increasing the area of the centre
part-spherical portion 34. The effect of these
recesses 44 on the inner walls of the feet i~ to provide extra
rigidity in this critical area and resistanc~ to deflection
of the central portion as will be e~plained.
In using the container, this will ~e Eilled with
carhonated beverage, and -the top will be sealed as
illustrated in Figure 6. ~s the internal pressure in
the container will increase with the passage of time,
so the plastics material of the container will "creep".
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1 ` Even although there is creep in the base 14, this
base will not essentially change shape, and the base
will not as a result of such creep become such as to
make the container unstabl.e. Thus, considering
Figure 5, before -the plastics material of the container
creeps, the surEaces of the fee-t 38 on which the container
is ree-standing lie i.n a p].ane marked A. As creeping
takes place, the central portion 34 moves downwards
to the position shown in dotted lines in Figure 5 and
the inner sides of the feet 38 roll inwardly and
downwardly. The formation oE the recesses 44 resist
this :ro:Lling inward~y and downwardly of th~ .eeet
inner sur:eaces, so that the bas:ic shape Oe tho base
i.s mainta:inec1 'rhe .~unct.i.on Oe the st~a~ portions
36 is important in that these strap portions resist
the downward movement oE the cen-tre portion 34 and prevent
it from moving through the new plane B in which the supp-
orting surfaces o~ the feet, after creep, are now located.
The con-tainer will still thereEore be free-standing :~
on the feet as the centre portion 34 remains alone, the
plane B containing the feet supporting surfaces. The
amount of creep which has taken place in the base can
be considered to be the spacing between the planes
A and B as shown in Figure S. The container also
undergoes slight overall increase in dimension as
a result o:E creep, but this is nowhere near
as great as in the base, due to tlle Eact that the
hoop s~ress resistance in the wall is greater than the
hoop stres~s resis-tance in the feet 38. In section,
the Eeet 38 are designed to be near spherical as
possible to give optimum hoop stress res.istance. The
specieic Eorm selec-ted Eor the base gives it extreme
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1 ~ rigidity, and combines this with the provlsion of
enabling the container to be free-standing on its
base. .
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It wilL be noticed that the shape of -the base in
the exampLe descri.bed i.s basically the same after creep,
as it wa.s heEore creep. It is not essential that this
be so, as the centre por-tion 34 could, at least prior to
creep, be concave inwards, conical inwards or conical
outwards, provided that a:fter creep the said central
portion remai.ns at a hei.yht greater than the supporting
surEaces of the feet ( I~:Lane B :in EicJu:re 5 ). Thus, :i.E
the central. port:ion 34 :is :in.iti.aL.Iy i.nwarcl:ly d.i.racted,
as the pressure ln-i:ido the CorltAi.ner increclse~, :it may
evert as we:Ll as creep, ~ut it should not be allowed
to come be:low plane B, taking i.nto accoun-t the overall :~
creep oE the base.
In the embodiment of the invention shown in Figs 7
to 11, the container is essential:Ly similar to and
is used in the same manner as, the container described
in relation to Figs 1 to 6. The exceptions are that
the wall 12A extends to the top flange 18A, and there
is no de-nesting ring 16, and also that the base has
six feet 32A which are, in section gerlerally
triangular in shape, w:ideni.n~ radial:Ly outwards as
shown in F:ig. 9. At the inr~r regions the Eeet 32A ~;. `
merge smoothly into the central portion 34A, whilst
at the outer recJion 40A the Eeet lie in a frustro
conica:L surEace of the same cone an~le as wall 12A.
The opposed :Eaces of ad~acent feet are much closer :~
3o than in the figs 1 to6 embodimen-t, and are generally . ~
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1 flat so as to define narrow strap portions 36A
and narrow radial gaps 37 between adjacent feet.
All corners and edges of the feet are rounded
off to provide maximum creep resistance and,
as in the case of the previous embodimen-t the
creep o:E the contai.ner base under internal pressure
is such that the central port:ion 34A does
not project through the p].ane on which the container
is free standing.
~t wi.ll. be appreciate~ that conta:iners havin~
the base construction according to the invention ar~
prineipa;Lly su:itab.l.e for app:l..icati.ons where:in ~h~r~
wi.lL b~ an over prossur~ ins:Ld~ the corltcl:iner .I.n
use, but the base cons~ructi.on :iE desired can also
be used in applieations where this over pressure will
be generated at will, for example, by heating of the
contents whilst still in the container.
The container can be construc-ted of any suitable
plastics material, although if it is designed
speeifically to hold a carbonated beverage, then it is
best to seleet a plastics material or combination .
of plastics material which will provide the best gas
barrier consistent with providing little or no extraetion
of monomer :Erom the plasties material into the beverage.
In partieula:r, the aerylonitriles are partieularly
suitable ~or these containers, espeeially nitrile
polymers base on acryloni-triles. The polyester plasties
are also ext;remely suitable as are some of -the polyol.efins,
in partieular polyethylene and polypropylene. The
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1 polypropylene and polyethylene are best used when it is possible
to provide a gas barrier internal layer for the container, such `
as a thin coating of nitrile polymer. -~
It is also to be appreciated that whilst in the ~;~
preferred case, the container is thermo-formed, it is possible to
produce the container by other methods, such as injection
moulding, although such method may at the present time turn out
to be more expensive than thermo-forminy.
The particular design and construction of these
containers enables them to be easily nested with other similar
containers.
Although the disclosure clescribes and illustrates
preerred embodiments o~ the invention, it .is to be understood
the invention i5 not restrictecl to this partlcular cmbod:Lment.
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