Note: Descriptions are shown in the official language in which they were submitted.
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Container Stopper
Id of the Invention
The present invention relates to improved stoppers for stoppering
openings in containers. In particular, the present invention relates to
improvements to container stoppers that have a film on at least one end to
protect the stopper from the contents of the container the stopper is utilised
in.
The stoppers of the invention are particularly useful as stoppers for openings
in
containers of fluids such as wine. The invention also relates to an improved
method of producing container stoppers such as the container stoppers of the
invention and packaged products, particularly packaged fluid products, in
which
a stopper of the invention is incorporated.
Backgiround of the Invention
A number of products are packaged in containers where the openings in
the container are stoppered. In these circumstances, it is typical that the
stopper
forms an interference fit with the container opening. One of the most common
products to be packaged in this way is wine although other fluid products are
packaged similarly. Traditionally, wine has been stored in bottles sealed with
cork stoppers. Cork stoppers have been used in the wine industry for a variety
of reasons most of which relate to the exceptional natural qualities of cork
as a
stopper. By way of example, cork is durable, resilient, free from rotting, is
sparingly permeable fo gas, is predominantly waterproof, readily compressible
and easy to shape. In many respects, therefore, cork is a natural material to
consider for sealing fluid in a container such as wine in a wine bottle.
There is always the danger when using any packaging material that
contaminants in the material used to form the packaging will contaminate the
final product leading to a consequent drop in final product quality. This is
particularly true for packaging materials that are used to package fluid
products.
In many instances the performance characteristics of the packaging material
may not properly take into account the effect of sustained contact between the
packaging material and the fluid product during storage. Such an effect is
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exacerbated in relation to wine where product is frequently stored for long
periods of time in the packaged state. The effect is particularly noticeable
with
stoppers as, in many instances, the characteristics of the material used to
produce the stopper are designed to provide ease of use of the stopper during
the packaging process rather than its performance during prolonged storage of
the container. As a result, other performance characteristics of the stopper
may
be compromised.
A perfect example of how contaminants in a stopper can affect product
quality is in the wine industry. The use of cork stoppers can lead to the
development of undesirable product characteristics when used to stopper a
container containing a wine. Cork can occasionally cause off flavours in wine
and it is often the cause of musty or mouldy taint and sometimes the cause of
off flavours due to oxidation. In 1994 the Quercus project was initiated by
the
European cork industry to reduce the occurrence of off flavours. Cork
producers now follow the European Cork Federation's Code of Practise to
reduce taint. TCA (2,4,6 Trichloroanisole) has been identified as the cause of
some musty/mouldy taint. Although cork is not the only source of TCA in wine
it
has been shown that some corks contain levels of TCA which are transferred to
wine when stored in bottles. It has also been observed that the taints can be
transferred to the wine via the vapour when the bottles are left standing up
and
the liquid does not contact the cork surface. This is due to corks poor
barrier to
volatile materials, demonstrated by its readiness to absorb and desorb
moisture
vapour with changes in relative humidity and its susceptibility to the entry
of the
volatiles which may be retained and later transferred to wine.
Another aspect to be considered when packaging products is whether
the product needs to be completely sealed off from the environment or whether
gaseous exchange is desirable. For example, with bottle storage of wine
consideration of the flavour development of the wine with aging has to be
taken
into account. The concept of bottle aging, bottle maturation or bottle
development is well known, however, little is understood or scientifically
proven
in this area. There is some belief that the stopper breathes and that oxygen
plays a role in bottle development of the wine, although it is well proven
that
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too much oxygen will oxidise a wine and ruin it. There is a growing body of
work that is developing the use of micro-oxygenation to develop flavour and
mature wines. Any stopper for use in the wine industry therefore should
preferably control the permeability of oxygen and allow in some cases some
oxygen to permeate the stopper and come into contact with the wine and in
other circumstances significantly block the ingress of oxygen.
A number of approaches have been developed aimed at overcoming the
problems of contamination of the product by the stopper whilst at the same
time
preferably retaining control of oxygen permeability. It has been shown that
coatings can be used to improve the performance of cork stoppers. Waxes and
paraffins may be used as coatings and applied to corks to improve the sealing
capability, for example. It has been observed that wax coatings also reduce
the
amount of liquid that soaks into the cork over time. Silicone coatings have
also
been applied to corks to improve the insertion and extraction of the cork. It
is
thought that the silicone reduces the friction between the cork and the bottle
during both the insertion and extraction processes. Coatings of this type are
typically applied to the corks while the corks are tumbling in a rotating
drum.
The corks may be tumbled with a solid wax block or a liquid is squirted or
otherwise sprayed onto corks. The coating is then spread from cork to cork by
the physical contact between the corks transferring the coating and evenly
distributing it. Heat may also be applied to aid the process.
There have been several attempts to place other forms of physical
barriers between the stopper and the wine to prevent the transmission of
tainting components to the wine. Many of these attempts have worked on the
principle of applying a coating layer on the end of the stopper in the form of
a
coating that is allowed to cure and dry as a film coating layer or in the form
of a
polymeric film attached to the end of the stopper. Unfortunately, the
characteristics of the stoppers produced using these techniques has been
unsatisfactory. Without wishing to be bound by theory, it is thought that the
problem with these approaches is that whilst the stopper is compressible, the
coating layer is typically not compressible. This leads to the development of
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imperfections in the coating layer such as cracking, peeling, creasing and the
like. Patent application WO 00/34140 purports to overcome these problems
and describes a composite stopper with a body and a thick moulded elastomer
plug located at the end of the stopper. The elastomer plug provides a seal to
the bottle and is claimed to be a taint barrier which allegedly prevents the
wine
touching the cork body of the stopper. The difficulty with this approach is
that
whilst it may overcome the taint problems it creates further problems and/or
has
a number of disadvantages. The unit cost of each stopper is significantly
higher
than the unit cost of cork stoppers in general and so is undesirable from an
economic standpoint. In addition elastomer plugs of the type described in this
patent have a high transmission rate for oxygen typically meaning that the use
of a plug of this type would not be expected to reduce the oxidation of the
wine
occurring on storage. As the exact orientation of the stopper into the opening
of
the container is crucial for the performance of the stopper, expensive capping
machinery is required in order to ensure adequate performance of the stopper
once fitted. This markedly slows production of bottled product when these
stoppers are used.
It would therefore be desirable to provide stoppers for containers that
overcome or substantially ameliorate the problems associated with
contamination of the contents of the container by the materials from which the
stopper is made whilst preferably still allowing for control of oxygen
transmission through the stopper.
The present applicants have made a study of the prior art stoppers and
have found that most of the deficiencies observed with the prior art coating
techniques were caused by the radial compression of the stopper during
insertion into an opening of a container. As this step could not be eliminated
from the packaging process, the applicants sought ways of controlling the
negative effects of this compression. As a result of their studies, the
applicants
surprisingly found that the observed problems were due not to the compression
of the stopper per se but rather were associated with the non-uniform
deformation of the film on end of the stopper during compression of the
stopper.
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It was found that this was a common problem as a majority of the materials
used in the formation of stoppers do not allow for uniform deformation of the
film
when the stopper is compressed. Lack of uniformity in deformation of the film
leads to the imperfections noted which, in turn, compromise the integrity of
the
5 layer. It was found if the effect of the non-uniform deformation of the film
could
be overcome, then the problems associated with the use of coating films could
be ameliorated. As part of their studies into coated stoppers, the applicants
have also developed an improved method for applying films to stoppers. This
method can be used in the production of the stoppers of the invention. A
surprising benefit provided by the new method is that although the stopper
deforms during the process, it does not produce a wrinkled film on the stopper
upon completion of the process.
Summar)~ of The Invention
In one aspect the present invention provides a container stopper
comprising a compressible body having at least one end for insertion into an
opening of a container, and a film on the end of the compressible body for
providing a protective layer between the compressible body and the container
contents; wherein at least a region at the end of the compressible body has at
least one property whereby upon compression of the body for insertion into an
opening of a container, said region compresses without substantially adversely
affecting the protective layer provided by the film. There are a number of
properties of the region at the end of the compressible body that, if present,
will
maintain the protective layer provided by the film. One property is that the
region at the end of the compressible body of the stopper is substantially
uniformly compressible in the plane of the surface at the end of the
compressible body.
In one aspect therefore the present invention provides a container
stopper comprising a compressible body having at least one end for insertion
into an opening of a container, the body comprising a region located at one
end
of the body presenting a surface, said region being substantially uniformly
compressible in the plane of the surface, and a film attached to the end of
the
compressible body for providing a protective layer between the compressible
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body and the container contents; whereby upon compression of the body for
insertion into an opening of a container said region compresses without
adversely affecting the protective layer provided by the film.
It has also been found that the same result can be achieved if the
property is such that the end of the body of the stopper is configured in a
manner such that the surface presented by the end of the body has a smaller
cross-sectional area than the cross sectional area of the stopper body. In yet
an
even further aspect therefore the present invention provides a container
stopper
comprising a compressible body having a cross sectional area and at least one
end for insertion into an opening of a container; and a film attached to the
end
of the compressible body for providing a protective layer between the
compressible body and the container contents; wherein at least a region at the
end of the compressible body tapers towards the end such that the end has a
cross sectional area less than the cross sectional area of the body whereby
upon compression of the body for insertion into the container opening the
region
compresses without adversely affecting the protective layer provided by the
film.
The invention further relates to packaged products where a stopper of
the invention is incorporated into the package. The packaged products are
preferably fluid products such as oils, wines or condiments.
Accordingly, in yet an even further aspect the invention comprises a
packaged product, said packaged product comprising a container having an
opening, a product located within said container and a container stopper
inserted into said opening wherein said container stopper comprises a
compressible body having at least one end inserted into said opening, and a
film attached to the end of the compressible body providing a protective layer
between the compressible body and the product in the container; wherein at
least a region at the end of the compressible body has one or more properties
such that upon compression of the body during insertion into the opening of
the
container said region compressed without adversely affecting the protective
layer provided by the film.
PCT/AU02/00877
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' - - Received 21 July 2003
7
In yet a further aspect the invention provides a packaged product, said
packaged product comprising a container having an opening, a product located
within said container and a container stopper inserted into said opening
wherein
said container stopper comprises a compressible body having a cross sectional
area and at least one end inserted into said opening; and a film attached to
the
end of the compressible body providing a protective layer between the
compressible body and the product; wherein at least a region at the end of the
compressible body tapers towards the end such that the end has a cross
sectional area less than the cross sectional area of the body whereby upon
compression of the body during insertion into the opening said end compressed
without adversely affecting the protective layer provided by the film.
In an even further aspect the invention provides packaged product, said
packaged product comprising a container having an opening, a product located
within said container and a container stopper inserted into said opening,
wherein said container stopper comprises a compressible body having at least
one end inserted into the opening, said body comprising a region located at
one
end of the body presenting a surface, said region being substantially
uniformly
compressible in the plane of the surface, and a film attached to the end of
the
compressible body providing a protective layer between the compressible body
and the product; whereby upon compression of the compressible body during
insertion into the opening of the container said region compressed without
adversely affecting the protective layer provided by the film.
In another aspect the present invention provides a container stopper
comprising a compressible body having a cross sectional area and at least one
end for insertion into an opening of a container; and a film attached to the
end
of the compressible body for providing a protective layer between the body of
compressible material and the container contents; wherein at least a region at
the end of the compressible body tapers towards said end such that said end
has a cross sectional area less than the cross sectional area of the body.
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Received 21 July 2003
7a
In yet another aspect the present invention provides a container stopper
comprising a compressible body having at least one end for insertion into an
opening of a container, said body comprising a region located at one end of
the
body presenting a surface, said region being substantially uniformly
compressible in the plane of the surface, and a film attached to the end of
the
compressible body for providing a protective layer between the compressible
body and the container contents.
The invention also provides a preferred method of producing a container
stopper with a polymeric film on at least one surface thereof, preferably an
end
surface. This method can be used to produce the container stoppers of the
invention referred to previously or may be used to produce any stopper with a
polymeric film on at least one surface. The method comprises the steps of
providing a container stopper, said stopper having a compressible body having
at least one end, the end presenting a surface; providing a polymeric film,
heating the polymeric film, and pressing the polymeric film and the surface
relatively together so as to attach the polymeric film to the surface wherein
the
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heating of the film occurs either simultaneously with, or prior to, the
pressing
step.
Description of the Figures
Figure 1. This shows a fragmentary side view of one end of a preferred
stopper of the invention.
Figure 2. This shows a side view of another preferred embodiment of the
stopper of the invention.
Figure 3. This shows a fragmentary longitudinal section of an end of a
preferred stopper of the invention.
Figure 4. This shows a longitudinal view of yet a further preferred stopper.
Figure 5. This shows a plan view of the stopper of figure 3 looking down line
V-V of figure 3.
Figure 6. A side view of a preferred stopper of the invention.
Figure 7. This shows a fragmentary longitudinal view of a preferred stopper
of the invention.
Figure 8. This shows a fragmentary longitudinal view of another preferred
stopper of the invention.
Figure 9. This shows a stopper located in a die prior to the application of a
film to the end of the stopper.
Figure 10. This shows the stopper in the die prior to the backing plates
forcing film onto the two ends of the stopper.
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Detailed Description of the Invention.
A requirement of a stopper for containers for the mass production of a
packaged product is the ability of the stopper to withstand the conditions
imposed on the stopper during manufacture of the finished product. One of the
principle conditions typically imposed upon stoppers irrespective of the
industry
in which they are utilised is that the stopper is compressed at least
partially prior
to its insertion into an opening in a container. The stopper then typically
expands once the compression force is released leading to a tight fit of the
stopper in the container opening. The stopper usually forming an interference
fit
with the opening in the container. In the wine industry bottling operations
typically utilise high speed stoppering machines which subject the stoppers to
large compression forces. These machines typically utilise a number of
compression jaws which radially compress the stopper body from its normal
diameter to a substantially smaller diameter, typically about one third of the
original size. A ram is then utilised to force the stopper from the jaws of
the
compression machine directly into the opening of the container where the
stopper attempts to expand to its original diameter, thus sealing the bottle.
A
typical cork used in the wine industry is approximately 45mm long with a
diameter of approximately 24mm. A typical internal diameter of the opening of
a
wine bottle is about 18mm. Significant compression of a stopper therefore
occurs in packaging of wine.
The improvements provided for stoppers disclosed in the present
invention are applicable to any compressible stopper with a film on at least
one
end. A feature of the stoppers of the present invention is that they have a
compressible body. It is preferred that the stopper body is sufficiently
compressible so that it can be compressed by at least 5%, more preferably at
least 10%, even more preferably at least 15%, even more preferably at least
20%, yet even more preferably at least 30%, even more preferably at least
40%, most preferably at least 50%. A number of materials may be used in the
construction of the body of the stoppers of the invention to achieve these
compressibility parameters.
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In essence, any material can be used as long as it meets the compression
criteria referred to above with those materials typically utilised in the
manufacture of stoppers being suitable. Materials that may be used in the
construction of the body portion of the stopper comprise cork, agglomerated
5 cork, micro-agglomerated cork, or 1+1 cork. Alternatively, the stopper body
may
be made from a polymeric material. The stopper body may comprise medium
density or low density, closed cell foamed plastic. Such foam plastics may
comprise one or more polymers selected from the group consisting of plastic
polymers, inert polymers, homopolymers, copolymers, terpolymers,
10 thermoplastic elastomers, and thermoplastic olefins. It is preferred that
the
closed cell foam plastic material comprises at least one polymer selected from
the group consisting of polyethylenes, metallocene catalysed polyethylenes,
polybutanes, polybutylenes, polyurethanes, silicones, vinyl based resins,
polyesters, ethylenic acrylic copolymers, ethylene-vinyl-acetate copolymers,
ethylene-methyl-acrylate copolymers, ethylene-butyl-acrylate copolymers,
ethylene-propylene-rubber, styrene butadiene rubber, ethylene-ethyl-acrylic
copolymers, ionomers, polypropylenes, copolymers or polyporpylenes and the
like. Examples of these types of materials are provided in U.S. patent
6,355,320.
The stopper body may also be made of fibres. Fibre stopper bodies are
disclosed in U.S. 5,665,462 and include vegetable fibres such as cotton, flax,
sisal, linen, cellulose and jute, and animal-derived fibres such as angora,
wool,
alpaca, and mixtures thereof. Synthetic fibres can also be used including
cellulose acetate, cellulose triacetate, acrylics, aromines (aromatic
polyamines),
rayons, polyolefins (e.g. polypropylene), nylons, polyesters, polyurethanes,
terylenes, teflon and mixtures thereof. Mixtures of the synthetic and/or
natural
fibres may also be used.
The gross shape of the stoppers of the invention may vary greatly with
the shape of the stopper body typically being determined by the shape of the
opening it is intended to be used in. As the stopper body preferably forms an
interference fit with the opening in the container in which it is used, it is
preferred that the stopper body has at least one end complementary in shape
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to the container opening. Thus, for example, the stopper body may be
rectangular, substantially cylindrical, or, indeed, any shape typically found
that
would be complementary to an opening of a container. The stopper body is
preferably elongate. A feature of the body of the stoppers of the invention is
that
they have at least one end, preferably two ends. It is this end of the stopper
body that is ultimately inserted into the opening in the container and forms
the
interference fit with the opening, thus providing the stopper performance. The
most preferred stoppers of the invention are elongate stoppers having a body
having two ends, the stopper body being substantially cylindrical. It is
preferred
that the dimensions of the stopper are such that it is from 30-60 mm in
length,
more preferably from 35-55 mm in length, even more preferably from 37-47 mm
in length, most preferably about 38 mm or about 45 mm in length. The stopper
body is preferably cylindrical with a diameter of from 18-30 mm, more
preferably
from 22-26 mm, even more preferably from 23-25 mm, most preferably 24 mm.
The stoppers of the present invention can be used with any container
having an opening which can be sealed with a stopper. It is preferred that the
container is a bottle and the stopper is shaped to fit into the opening of the
bottle, namely the mouth of the bottle.
The stoppers of the invention have a film on at least one end of the body
which provides a protective layer between the body of the stopper and the
contents of the container once the stopper has been inserted into the
container
opening. If the stopper body only has one end, the film is located on that
end. If
the stopper body has more than one end, the film may be on only one of the
ends or on a number of ends. Thus, where the stopper body has two ends, the
film may be on only one end or may be on both ends. If there are two ends it
is
preferred that the film is on both ends.
It is preferred that the film only covers the end of the body and does not
travel beyond the end of the uncompressed body such as down the sides of the
body.
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It is preferred, therefore, that the film completely covers the end of the
uncompressed stopper but does not travel beyond the end of the stopper.
The improved stoppers in accordance with the invention may utilise a
number of different films. The film may be a coating layer that has been
applied
as a liquid and allowed to cure or a coating layer that has been sprayed on or
otherwise applied to the stopper body. The film may also be a polymeric film.
It is preferred that the film is a polymeric film, preferably a multilayer
polymeric film. The polymeric film preferably comprises a barrier layer and an
adhesive layer. The barrier layer preferably has a low permeability to H20, O~
and C02 and is preferably substantially impermeable to organic molecules with
molecular weights greater than 40. A number of materials are known that can
be used to produce barrier layers for use in the invention stopper.
Preferably,
the barrier layer comprises one or more polymers or materials selected from
the
group consisting of polyethylene, polypropylene, polyethylene Terepthalate,
ethylene-vinylacetate polymers, polyvinylchloride, polydivinylchloride,
polyvinyldichloride, polyvinylacetates, nylon, polyvinyl alcohols,
polyurethane,
polyacrylonitrile, cellophane, surane, polyamines, polycarbonates,
polystyrene,
polyalkylene oxides, polyethylene oxides, cellulose, cellulose derivatives,
and
silicon polymers or metal foils. A preferred barrier layer comprises nylon or
cellulose, polyethylene and PVDC or metal or EVOH. The barrier layer may be
any thickness typically utilised in the art. It is preferred that the barrier
layer is
between 1 to 50 micron, preferably 2 to 40 micron, more preferably 5 to 30
micron, most preferably 10 to 30 micron.
The film also preferably includes an adhesive layer. The adhesive layer
may be added to the 'film prior to application to the stopper body by way of a
spray or may be laminated onto the film prior to application of the film to
the
stopper body. Suitable adhesive layers include those selected from the group
consisting of hot melt adhesives or heat activated adhesives. Suitable
adhesives therefore include polyethylene vinyl acetate, polyamides, acrylics,
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methyl methacrylate based polymers, starch based adhesives, carbohydrate
based adhesives, protein based adhesives, animal glues, rubbers, silicones,
epoxy resins, melamine-formaldehyde based adhesives, unsaturated
polyesters, urea-formaldehyde resins, resorcinols, phenolic adhesives,
urethanes, polysulfides, polyvinyl and ethylene vinyl acetate polymers.
Particularly preferred adhesive layers are ethylene vinyl acetate polymers.
The adhesive layer preferably has a thickness of between 0.1 to 15
micron, more preferably 4 to 15 micron, most preferably 10 to 15 micron. If a
heat activated adhesive is used, it preferably has an activation temperature
greater than 30°C, more preferably greater than 50°C, most
preferably greater
than 80°C.
The stoppers of the invention have at least a region at an end of the
compressible body which has at least one property such that upon compression
of the body for insertion into an opening of a container, the region
compresses
without substantially adversely affecting the protective layer provided by the
film. If the body has more than one end, a region of this type may be located
at
either end or there may be a region located at each end. The region may be
integral with the remainder of the stopper body or may be attached to the
remainder of the stopper body to form a composite stopper body. There are a
number of properties the region may have which will provide the desired
result.
One property of the region is for it to taper toward the end at which it is
located in such a way that the end of the stopper has a surface area that is
less
than the cross-sectional area of the remainder of the stopper body. In one
preferred embodiment therefore, the property of the end of the stopper that
provides an improved stopper is that at least a portion of the region at the
end
of the stopper tapers towards the end of the compressible body. The taper is
such that the cross-sectional area of the end is less than the cross-sectional
area of the body. It is found that only minor tapers are required as only
minor
reductions in the cross-sectional area of the end of the stopper body are
required to maintain the protective integrity of the film. The taper is
preferably
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such that the cross-sectional area of the end is less than 98% of the cross-
sectional area of the body, more preferably less than 96%, even more
preferably less than 92%, more preferably less than 85%, even more preferably
less than 80%, yet more preferably less than 75%, most preferably less than
70% of the cross-sectional area of the body. Particularly preferred ranges of
the
taper are such that the cross-sectional area end of the stopper is between 65%
and 85% of the cross-sectional area of the body. Without wishing to be bound
by theory, it is though that such a reduction allows for the control of the
deformation of the film on compression of the body.
It has been found that any of a number of different tapers can be used to
provide the desired performance characteristics. For example, the taper may
be a uniform or a non-uniform taper. By uniform taper it is meant that the
reduction in thickness of the stopper body is constant as it approaches the
end.
It is preferred, however, that the taper is a uniform taper as this is most
easily
mass produced and therefore the most desirable economically. At least in
principle, however, any type of taper may be used. Thus, the side of the body
as it tapers may be straight or curved in shape. It is preferred that the
taper not
be so extensive that the end of the body on which the film is located become
smaller than the opening of the bottle it is intended to seal. If this occurs,
there
is a compromise of the effectiveness of the protective layer provided by the
film.
It is preferred that the taper only continue for a minor portion of the
stopper
body. It is preferred that the taper occurs on less than 30% of the stopper
body,
even more preferably less than 20% of the stopper body, more preferably less
than 10%, yet even more preferably less than 5%, even more preferably on less
than 2%, most preferably less than 1 % of the stopper body. It is found that
the
taper is equally effective if it is located essentially only at the end
although in
principle, the taper may traverse almost the entire length of the stopper
body.
One preferred method of forming the taper of the stopper body is to produce a
stopper and then chamfer the end to achieve a tapered stopper body. This step
of chamfering the stopper body may occur either before or after the attachment
of a film to the end of the body. The following tables (1 ) and (2) list the
relative
surface area with different size chamfers for a number of different size
stopper
body diameters.
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TABLE 1
Total
Chamfer
Size
(mm)
0 0.2 0.5 1
Cork Sa Sa Ra Sa Ra Sa Ra
Dia
(mm)
22 380.13 373.25 0.982 363.05 0.955 346.46 0.911
23 415.48 408.28 0.983 397.61 0.956 380.13 0.914
23.5 433.74 426.38 0.983 415.48 0.957 397.61 0.916
24 452.39 444.88 0.983 433.74 0.958 415.48 0.918
24.5 471.44 463.77 0.984 452.39 0.959 433.74 0.920
490.87 483.05 0.984 471.44 0.960 452.39 0.921
706.86 697.47 0.987 683.49 0.966 660.52 0.934
TABLE 2
Total
Chamfer
Size
(mm)
0 2 3 4
Cork Sa Sa Ra Sa Ra Sa Ra
Dia
(mm)
22 380.13 314.16 0.826 285.53 0.745 254.47 0.669
23 415.48 346.36 0.833 314.16 0.756 283.53 0.682
23.5 433.74 363.05 0.837 330.06 0.760 298.65 0.688
24 452.39 380.13 0.840 346.36 0.765 314.16 0.694
24.5 471.44 397.61 0.843 363.05 0.770 330.06 0.700
25 490.87 415.48 0.846 380.13 0.774 346.36 0.705
30 706.86 615.75 0.871 572.56 0.81 530.93 0.751
5
In the tables, total chamfer size indicates the total amount of chamfer when
the
chamfer at the two sides of the body are added together. Thus, with a chamfer
size of 2, there has been approximately 1 mm of stopper body removed from
each side.
10 Sa = Surface area (mm2)
Ra = Surface area of end of chamfered cork/cross-sectional area of cork
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It is preferred that the stopper body has two ends. It is particularly
preferred
when using the property of a tapered body to produce the improved stoppers
that where there are two ends, then both of the ends of the compressible body
are tapered. If this occurs, it is preferred that both ends are tapered in the
same
manner and to the same extent. The advantage of this is that stoppers of this
type can be used in conventional bottling machines which do not discriminate
between the two ends of the stopper. Therefore, using stoppers with two ends
with similar tapers on the ends allows the stopper to perform the desired
function irrespective of the end of the stopper selected by the machine for
insertion into the bottle.
In addition to machining a stopper body (either before or after application
of a film) to achieve the taper discussed above, the taper may also be
achieved
by attaching a pre-tapered layer or disc to one or more ends of a stopper body
to produce a composite stopper body with a tapered region at least, one end.
Whilst this technique can be utilised, it is not preferred as it is not cost-
effective
as these stoppers then become expensive to produce relative to the machining
technique. As would be clear to a skilled addressee, a combination of these
techniques may be used. Of course, with stopper bodies that are produced by
moulding processes, the taper may be built into the mould leading to a formed
stopper having a taper.
Another property of the region at the end of the body of the stopper that
can be exploited to achieve the desired results, is to provide a stopper with
a
region at one end of the body where the region is substantially uniformly
compressible in the plane of the surface defined by that region. By
substantially
uniformly compressible as used herein, it is meant that when the region is
subjected to a defined force in a first direction, the amount of deformation
in that
direction is substantially the same as the amount of deformation observed if
the
region was subjected to a similar force in a different direction.
Alternatively, if
the end of the region does not present a planar surface, it is preferred that
the
region is substantially uniformly compressible in a plane perpendicular to the
longitudinal axis of the opening of the container that the stopper is intended
to
seal. It is found if the region at the end of the body portion is
substantially
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uniformly compressible in this plane, then the deformation properties of a
film
coated on the region are such that the compression does not compromise the
efficacy of the protective layer formed by the film. Whilst there will almost
always be some degradation of the film properties on compression, these can
be minimised within acceptable bounds.
There are many ways of achieving substantially uniform compressibility
of the region at the end of the stopper. One preferred method is to ensure
that
the stopper body is made from a uniformly compressible material. When using
natural cork, for example, it is difficult to achieve uniform compressibility
as
natural cork is typically cut from the tree in a manner such that the growth
rings
of the tree occur throughout the cork. Use of these materials typically do not
allow for the uniform compressibility of the cork material as the growth rings
produce zones of different compressibility. If, however, the stopper body
comprises cork cut from cork trees in such a manner that the cork is cut
transverse to the typical direction of cutting the cork stopper from the tree,
improved uniformity can be achieved. Agglomerate corks are produced by
extruding a mixture of adhesive and cork granules through a heated die to
produce a rod which is cut and ground to a cylindrical stopper. During granule
feed from the hopper and the extrusion process, different sized granules
preferentially position themselves so that the final cork is not entirely
homogenous. In addition, each individual granule has different compression
properties and is oriented differently. As a result, agglomerated corks are
more
uniformly deformed under radial compression than natural cork stoppers cut in
the usual direction, however, they are not precisely uniform during radial
compression. Therefore, with some films with particular stiffness and adhesion
properties, agglomerated cork may provide the degree of compression
uniformity required.
Another way of achieving the same result is to attach a material that is
substantially uniform compressible in the plane of the surface such as a disc
or
layer on the end of the body to form a composite stopper body having a region
at one end that is substantially uniformly compressible in the plane of the
surface defined by the region. When using a disc or layer of uniformly
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18
compressible material attached to the stopper to form a composite stopper body
it is found that the important characteristic is the compression behaviour of
the
disc or layer, not the entire stopper body per se. Thus, as long as the
compression characteristics of the disc or layer are acceptable, then a lack
of
uniformity in the compression characteristics of the remainder of the stopper
body will be irrelevant. It is preferred that if the stopper has two ends,
then a
region of uniformly compressible material is located at each end. There are
any
number of uniformly compressible materials that could be utilised in the
formation of the disc or layer discussed above and these would be clear to a
skilled addressee. In principle, any substantially uniformly compressible
material
could be used. A skilled worker in the art would be able to quickly determine
whether a material was uniformly compressible by the use of simple
compression tests.
Of course a number of properties of the region at the end of the stopper
body may act in concert to produce the improved stoppers. Thus, in a
particularly preferred embodiment, at least a region at the end of the stopper
body tapers toward said end and is also uniformly compressible in the plane of
the surface at the end of the stopper body presented by the region. If the
stopper has two ends it is preferred that this occurs at each end.
The invention also relates to products packaged using the invention
stoppers. The preferred packaged products of the invention are fluid products
and, in particular, oils, wines and vinegar. The preferred containers for use
with
the packaged products of the invention are bottles, preferably glass bottles.
In a further embodiment, the invention provides a method of producing a
container stopper with a polymeric film on at least one surface thereof for
protecting said surface said method comprising the steps of
(a) providing a container stopper, said stopper having a compressible
body having at least one end, said end presenting a surface;
(b) providing a polymeric film,
(c) heating the polymeric film, and
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(d) pressing the polymeric film and the surface relatively together so
as to attach the film to the surface, wherein the step of heating the
film occurs either simultaneously with, or prior to, the pressing
step.
It is preferred that the step of providing a container stopper comprises
positioning a container stopper in a stopper holding means. A preferred
stopper
holding means is a die having an internal cavity for receiving the stopper.
The
preferred internal dimensions of the cavity ranges from 4 mm smaller to 4 mm
larger than the external dimensions of the stopper to be subjected to the
process. It is particularly preferred that the internal dimensions of the
cavity
match the external dimensions of the stopper. A smaller dimension on the
cavity
allows for the stopper to be firmly held in position throughout the process
while
a larger dimension allows the film to overhang the end of the stopper if
required.
The preferred die has a length less than the length of the stopper such that
at
least a portion of the stopper protrudes from the cavity in the die. The form
of
the die will depend on the shape of the stopper to be subjected to the method.
It
is preferred that the shape of the internal cavity of the die is complementary
to
the shape of the stopper body. The die can be configured so only one end of
the stopper is subjected to the method (in these cases one end of the die has
a
blank to prevent the stopper from protruding from both ends of the cavity) or
such that two ends of a stopper can be treated simultaneously in which case
both ends of the die are open and the die is substantially tubular to allow
the
stopper to protrude from each open end.
The type of stoppers that can be subjected to the process are the
stoppers described hereinbefore. The stoppers that may be subjected to the
process may have a film on at least a surface such as an end or may, prior to
subjecting to the process, be devoid of film. The films that can be used in
the
method are those polymeric films described hereinbefore.
Once the stopper has been provided in the desired orientation for
application of a polymeric film, a suitable polymeric film is provided. In a
preferred embodiment, the polymeric film is provided as a continuous polymeric
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film, spooled between two film holding elements. The polymeric film typically
spools between these two film holding elements. The film holding elements are
preferably arranged so as to be able to cooperate to advance the film in
either
direction as required. The film holding elements are preferably arranged or
5 oriented such that that one surface of the polymeric film is in
substantially the
same plane as the surface of the end of the stopper to which the polymeric
film
is intended to be attached. It is preferred that the polymeric film comprises
an
adhesive layer as an outer layer and that the orientation of the film is such
that
the side of the film opposing the end of the stopper has the adhesive layer as
10 the outer layer.
In the process of the invention the film is heated prior to or
simultaneously with the pressing step. The heating may be achieved in a
number of ways including pre-heating of the film prior to the pressing step by
15 means of a heated blast of air or other gas blown over the surface of the
film. It
is also possible for the film to be passed through a heating chamber or heated
zone prior to the pressing step in which case heat is transferred to the film
in the
heating chamber or heating zone. The heating can also be applied by heating
the die holding the stopper or, alternatively, the backing plate that forces
the film
20 on to the stopper can be at an elevated temperature such that heat is
transferred to the film on pressing. It is preferred that the heating is such
that
the film is heated to at a temperature sufficient to soften, melt or activate
the
outer layer of the film typically at least 40°C, preferably at least
80°C, more
preferably at least 120°C.
In the process of the invention, the film and the surface of the stopper are
pressed relatively together so as to attach the film to the surface. There are
a
number of ways in which the relative pressing together of the polymeric film
and
the stopper surface can be achieved. Thus, for example, the polymeric film can
be held in place and the stopper surface pressed against the film. If this is
the
case, a backing plate is typically utilised to ensure the film does not deform
away from the stopper on pressing. Alternatively, both film and die may move
relative to each other to press the stopper surface and polymeric film
together. It
is preferred, however, that the stopper is held relatively securely and the
film
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pressed onto the surface of the stopper by way of a moveable backing plate. It
is preferred that the backing plate cooperates with the die in which the
stopper
is held during pressing to cut the film such that the film is only located on
the
surface of the end of the stopper. It is preferred that the pressing is
carried out
with sufficient force to compress the compressible body of the stopper by at
least 0.5%, more preferably at least 1 %, more preferably at least 2%, yet
even
more preferably at least 3%, even more preferably at least 10%, most
preferably at least 15%. The pressing step may in theory be carried out for
any
period of time. It is preferred, however, that it is carried out for between
0.1 to
60 seconds, more preferably 0.1 to 15 seconds, most preferably 0.1 to 5
seconds. On completion of pressing the force is removed by removing the
backing plate.
The process of invention can occur in such a way that only one end of the
stopper is treated or, alternatively, both ends of the stopper can be
simultaneously treated by the process described above. In this manner, two
backing plates are utilised with two polymeric films. Upon completion of the
pressing step, the backing plate or plates are released so as to reduce
pressure. If the process is run as a continuous process, the film is then
advanced, a further stopper is provided and the process repeated. One way of
achieving this is to have a number of dies arranged on an axle or slide
wherein,
after treatment of one stopper is complete, the axle or slide advances to a
further position to present a new stopper to be treated and the treated
stopper is
punched out with a ram and replaced. This allows the process to be relatively
efficient and time and cost-effective and can therefore be run as a continuous
process.
The above description provides an overview of the inventive stopper and
process of the invention. The invention will now be further described with
reference to the accompanying drawings.
A fragmentary view of one end of the stopper is shown in Figure 1. There
is a film (1) on the end of the stopper body and a region (2) at the end of
the
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stopper body that is substantially uniformly compressible in the plane of the
surface presented by the region at the end of the stopper body.
Figure 2 shows a view of yet a further preferred stopper of the invention
with film (1) located on each end. There are regions (2) at each end of the
stopper, each of the regions being substantially uniformly compressible in the
plane of the surface at the end of the stopper presented by the region. In
this
embodiment this substantially uniformly compressible region is located at each
end of the stopper and allows for use of the stopper in automated stoppering
machines.
Figure 3 shows a cross-sectional fragmentary view of yet a further
preferred stopper of the invention. The stopper in Figure 3 incorporates a
taper.
There is a film (1) located on the end surface of the stopper body (3) with
the
taper at the end of the stopper body indicated by tapering sides (4) and (5),
being such that the cross-sectional area of the surface of the end of the
stopper
on which the film (1 ) is located, being less than the cross-sectional area of
the
stopper body.
Figure 4 is a cross-sectional side view of a preferred stopper of the
invention with a taper at both ends. A film (1) is located on each end of the
stopper body (3). Each end of the stopper body tapers as shown such that the
surface area of the ends covered by the film (1) is less than the cross-
sectional
area of the stopper.
Figure 5 shows a plan view looking down line V-V shown in Figure 3. The
outer ring (6) represents the sides of the stopper body and the inner ring (7)
represents the surface at the end of the stopper body after the taper.
Figure 6 represents a particularly preferred embodiment of the invention.
This embodiment demonstrates the combined effect of a taper and a
substantially uniformly compressible region at the end of the body. The
stopper
has a stopper body (3) with a film (1) located on each end. At each end of the
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stopper body, there are substantially uniformly compressible regions (2) with
at
least a portion of each of the regions being tapered such that each of the
ends
has a cross-sectional area that is less than the cross-sectional area of the
body.
The tapered body sides (4) and (5) are clearly shown.
Figures 7 and 8 show different preferred tapers at the ends of the
stopper body. Thus, in Figure 7 there is a stopper body (3) with a film (1) on
the
end thereof. There are tapered sides (4) and (5). The extent of the taper
inFigure 7 is less than the taper shown in Figures 3 and 4 and shows how the
angle of the taper can be varied.
In Figure 8 there is a stopper body (3) with a film (1) located on one end.
In this case, the edges (8) and (9) are tapered such that they are rounded
with
the end of the stopper having a lower cross-sectional area than the cross
sectional area of the stopper body.
Figure 9 shows a stopper body (3) located with a stopper holding means.
The two ends of the stopper protrude from the ends of the stopper holding
means.
Figure 10 is a schematic of the process of the invention immediately prior
to the pressing step. There is a stopper holding means (11) with two ends of a
stopper (12) and (13) protruding therefrom as in Figure 9. There are two
polymeric films (14) and (15) provided as part of a continuous film and
backing
plates (16) and (17) which are arranged to press the film onto the ends of the
stopper. After the compression is complete, the backing plates (16) and (17)
are
released and the film advances in the direction shown to treat a further
stopper.
As shown, the polymeric films include voids (18) and (19) showing where
polymeric film has been punched out of the continuous film during treatment of
the previous stopper.
The present invention will now be more fully described with reference to
the accompanying example. It should be understood, however, that the
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description following is illustrative only and should not be taken in any way
as a
restriction on the generality of the invention described above.
Example 1
Coating Films Preparation
A 20 micron multilayer film containing a 15 micron high density
polyethylene layer with a 5 micron ethylene-vinyl acetate copolymer (EVA)
layer
was produce using conventional coextrusion blown film equipment.
A 40 micron multilayer film containing layers of EVA/PE/PVDC/Nylon
was produced by extrusion and laminating using conventional techniques.
Producing Cork StJopers With End Film Coating
A cutting tool was manufactured 26 mm in diameter with an internal
cylindrical cavity 42 mm deep. Corks of 24 mm diameter, 45 mm length were
taken from a batch of commercial corks. The ends the corks were coated with
both the EVA/PE/PVDC/Nylon film and polyethylene/EVA film in one step using
the tool described by pressing the cork onto a heated backing plate
(125°C)
with the cork inside the cutting tool, the films held between the cork and the
backing plate. Each of the corks was then measured to determine the ratio of
the diameter of the film versus the diameter of the cork.
.'. R = Diameter of the film
Diameter of the cork body
Thus, where the film was located only on the end of the stopper body and
completely covering it R=1.00. Where there was an overlay of film over the end
of the stopper R=1.08.
Chamfering the Coated Corks to Reduce the R value
A number of the coated corks were then chamfered by rotating the edges
on sandpaper to produce tapered corks. In these cases, the cross-sectional
area of the surface of the stopper was less than the cross-sectional area of
the
body of the stopper. R values of 0.92, 0.83, 0.79 and 0.75 were thereby
produced.
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Wax and silicone coating
The corks were waxed and silicone coated by tumbling 100 corks with solid
paraffin wax for 20 minutes and then with squirting 1 ml of 7004 CAF silicone
on
the corks and tumbling for a further 30 minutes. This was done to improve
5 insertion of the corks into the bottle neck.
The Effect of R and the ratio of the surface area of the end of the stopper
value
on Gas transmission
The amount of air that enters the bottle at bottling can be seen by
10 applying a vacuum at bottling and inverting the bottle and watching the air
bubbles that stream into the bottle. (0 - no streaming; 5 - maximum amount of
streaming)
R value Area Ra - Quantity of bubbles
entering bottle
1.08 531 1.17 5
1.0 453 1 4
0.92 380 0.84 3.5
0.83 314 0.69 1
0.79 284 0.63 0
0.75 255 0.56 1.5
15 Ra = Surface area of end of stopper/cross-sectional area of the stopper.
It is clear that oxygen transmission is at optimal levels when the stopper
body
has a taper. As would be clear to a skilled addressee, it would be expected
that
the optimal taper will vary according to the properties of the compressible
20 material of the stopper, the properties of the coating film and the
dimensions of
the opening into which it is ultimately inserted.
Example 2
Cork Travel Test
25 Another test that distinguishes the sealing ability of corks is known as
the
Travel Test. This test measures the number of bottles that allow wine to
travel
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up between the cork and the bottle neck. The distance the wine travels is
recorded. The test is accelerated by laying the bottles down and heating them
to 30°C for a week. The heat increases the pressure the wine exerts on
the
seal. With film coated corks travel is usually associated with wine soaking
underneath the film. The degree of this under soak can also be measured.
Four coated corks were tested by this method. Some of the corks were
altered by gluing a 4 mm thick transverse cut cork disk onto the end of the
cork
prior to coating with a polymer film. Each cork type was 24 mm diameter by 44
mm long in their completed form.
Transverse cut means the disk was cut in a direction perpendicular to the
direction cork for wine stoppers is usually cut. The end face of the disk
originally
faced into or away from the tree trunk. Therefore the lenticels (or air holes
that
originally allowed air to pass through the bark to the tree) pass from one
face of
the disk to the other. Natural cork stoppers are not cut in this direction
because
the wine can travel up through the lenticels from the inside end of the cork
to
the outside end. Usually, the end face of a cork stopper originally faced
either
the ground or the sky and the lenticels pass across the body of the cork. When
compressed radially the transverse cut disk, although not precisely uniform,
has
a much greater uniformity of deformation than the usually cut cork stopper.
Meaning that when a force is applied at the edge of the disk towards the
disk's
centre, the deformation is similar to the deformation achieved when a similar
force is applied to another point on the edge of the disk and directed towards
the centre of the disk. When cork is cut in the usual way with the ends
originally
pointing to the ground and sky, the deformation uniformity is poor due to
growth
rings and the shape and orientation of the unit cells making up the cork.
The four cork types were
1. Straight natural cork
2. ~ Straight natural cork with 2 mm diameter chamfer
3. Cork with a transverse cut cork disk glued on end
4. Cork with a transverse cut cork disk glued on end with a 2 mm chamfer.
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Prior to any chamfering being done, each of the corks was coated with a
60 micron film consisting of the layers EVA/PEIPVDC/Nylon/EVA/HDPE by
heating and pressing the film onto the cork at 125°C as described in
example 1.
Prior to bottling, the corks were coated with wax and silicone by tumbling for
60
minutes with approximately 0.0087g wax and 0.0064g of silicone per cork. The
travel and under film soak results for six repeats of each cork after storage
at
30°C for three weeks were as shown in the following table.
Cork % without % travel % travel % with % with soak
No travel less greater no under film
than 5 mm than soak undergreater than
5 mm the film 30% of area
1 0 50 50 0 83
2 0 100 0 33 33
3 67 33 0 83 13
4 100 0 0 100 0
It is clear from the above that stoppers with a chamfered end have improved
performance characteristics as opposed to natural cork. It is also clear that
the
use of a substantially uniformly compressible region or layer on the end of
the
stopper body also improves stopper performance. A combination of these
features is clearly superior.
20
