U.S. patent application number 13/184043 was filed with the patent office on 2011-11-03 for method for producing a thin-walled container.
This patent application is currently assigned to TECSOR HR. Invention is credited to Jean-Tristan Outreman.
Application Number | 20110266722 13/184043 |
Document ID | / |
Family ID | 39322628 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110266722 |
Kind Code |
A1 |
Outreman; Jean-Tristan |
November 3, 2011 |
METHOD FOR PRODUCING A THIN-WALLED CONTAINER
Abstract
This invention relates to a method for producing a thin-walled
container, characterized in that a preform is deformed using a
weight/wall surface ratio on the order of about 150 g/m.sup.2 to
250 g/m.sup.2.
Inventors: |
Outreman; Jean-Tristan; (St
Maximin la Ste Baume, FR) |
Assignee: |
TECSOR HR
Meyreuil
FR
|
Family ID: |
39322628 |
Appl. No.: |
13/184043 |
Filed: |
July 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12681931 |
Apr 7, 2010 |
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PCT/FR08/51826 |
Oct 9, 2008 |
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13184043 |
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Current U.S.
Class: |
264/523 |
Current CPC
Class: |
B29C 49/64 20130101;
B65B 3/022 20130101; B29K 2067/00 20130101 |
Class at
Publication: |
264/523 |
International
Class: |
B29C 49/08 20060101
B29C049/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2007 |
FR |
0758185 |
Claims
1. A process for manufacturing a thin-walled container,
characterized in that it consists in deforming a preformed shape by
using a material weight/wall surface ratio on the order of 150
g/m.sup.2 to 250 g/m.sup.2.
2. A process for manufacturing a thin-walled container according to
claim 1, wherein it consists in deforming a preformed shape by
using a material weight/wall surface ratio on the order of 150
g/m.sup.2to 200 g/m.sup.2.
3. A process for manufacturing a thin-walled container according to
claim 1, wherein the deformation of the preformed shape is carried
out by a blowing process.
4. A process for manufacturing a thin-walled container according to
claim 3, wherein the blowing is exerted in two directions,
longitudinal and radial, so as to obtain a bi-oriented
container.
5. A process for manufacturing a thin-walled container according to
claim 1, wherein it consists in using polyethylene terephthalate
(PET).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of application Ser. No.
12/681,931, filed Apr. 7, 2010, now pending, which claims priority
to International Application No. PCT/FRO8/51826, filed Oct. 9,
2008, which claims priority to French Application No. 0758185,
filed Oct. 10, 2007, the entire contents of which are herein
incorporated by reference.
TECHNICAL FIELD
[0002] This invention relates to a method for producing a
thin-walled container, characterized in that a preform is deformed
using a weight/wall surface ratio on the order of about 150
g/m.sup.2 to 250 g/m.sup.2.
BACKGROUND
[0003] This invention relates to a process for manufacturing a
thin-walled container and the process for pressurizing this full
container.
[0004] In the farm produce industry, in particular that of
beverages, the high-volume, thin-walled containers are a particular
problem.
[0005] The thin-walled containers are known in, for example, the
patent applications WO-03/033361, EP-1468930 and EP-1527999.
[0006] These containers are very attractive for small volumes of
less than 2 liters, because beyond this, the products that are
produced according to the teaching of these patents are relatively
heavy because the amount of material is linked to the parameter of
the volume of these containers.
[0007] The increase of the surface area of a package is not
proportional to that of the volume of said package. Therefore, for
volumes of more than 2 liters, it is entirely possible to reduce
the weight of the packages while ensuring good mechanical stability
after packaging.
[0008] In addition, these containers exhibit the necessity for a
pressurization of the inner volume that is not satisfactory as
explained below.
[0009] In addition, for economic reasons that are easily
understood, the object is to reduce the amount of material that is
necessary for the production of these thin-walled containers, as
much for reducing the production costs as for reducing the
recycling costs, which the prior art does not allow since as soon
as the volumes become greater than 2 liters, in particular, the
weight of the material increases very significantly since it is
linked to the volume, therefore a cubic factor.
[0010] These containers are disposable, and it would be
advantageous to avoid unnecessary sophistication for the use to
which they are put, hence the increased importance of the
thin-walled containers but with an identical manufacturing process
that allows a range going from small containers of several
centiliters up to high volumes of one to several tens of liters by
avoiding an excessive increase of the weight of the material.
[0011] In addition to the problem of reducing the amount of
material, it is possible to mention another problem, that of
rigidity, which proportionally decreases with the amount of
material.
[0012] For these containers that are manufactured by the process
according to the invention, with a reduced amount of material, the
rigidity of the container that is obtained is inadequate.
[0013] This rigidity is inadequate for allowing good gripping
before opening, and primarily this low rigidity makes difficult,
and even impossible, a superposition of these full containers, in
particular when they are palletized and the pallets are stacked on
one another.
[0014] In addition, the rigidity of such a thin-walled container
poses another problem because these containers are packaged at
ambient temperature and when these containers are placed in a cold
environment, a collapsing phenomenon occurs that produces
deformations of the container and poor stability during
gripping.
[0015] In general, the thin-walled containers are filled under cold
conditions with flat liquids such as mineral water, oil, fruit
juices, or milk.
[0016] Then, to meet the requirement of rigidity, it is provided to
put these thin-walled containers under internal pressure by
resorting in particular to the so-called nitrogen drop process that
is currently used industrially or to any other analogous
process.
[0017] This nitrogen drop process that is taken as an example
consists in introducing a drop of liquid nitrogen into the
liquid-filled container to be packaged immediately before the head
space of the container is sealed.
[0018] Immediately after sealing, this drop of liquid nitrogen is
transformed into gas. The increase in volume in the head space
leads to a rise in pressure in the interior of the container and
therefore to a rigidification of said container. This increase in
pressure nevertheless remains relatively low on the order of
one-tenth of a bar.
[0019] However, this process of the drop of nitrogen poses a
certain number of problems. First of all, the metering of the
volume that is introduced is difficult; however, the final pressure
depends on the amount that is introduced, working conditions, and
the length of time of sealing. Then, the distribution means of this
drop of nitrogen should be integrated in the chain, and, as a
result, they should therefore be adapted. In addition, when the
packaging is produced aseptically, this adaptation is a high
stress: requirements of cleaning, sterilization, and maintenance.
An additional station involves an additional source of failure with
the stopping of a chain. In the case of an aseptic packaging chain,
this intervention proves still more difficult because the
interventions are difficult and time-consuming since it is
necessary to restore the unit to aseptic packaging conditions.
[0020] In addition, it is noted that the liquid nitrogen, at a
greatly negative temperature, drops in the liquid to ambient
temperature although the fall of the drop uniformly causes
splashing on the edges of the container.
[0021] These splashes of the contained fluid, such as mineral
water, fruit juice, and oil, can degrade after packaging, during
the storage, leading to the development of mold before the product
is marketed and therefore before the product is consumed, which is
not satisfactory.
[0022] The material that is used for manufacturing the thin-walled
containers is often PET, polyethylene terephthalate, known for its
transparency, its low weight, and its great shaping possibilities.
The PET also allows good preservation of contained liquids.
SUMMARY
[0023] This invention proposes a process for manufacturing a
thin-walled container as well as a process for pressurizing said
container that is filled under cold conditions and that contains a
flat liquid so as to increase the rigidity of said container before
opening, a process that compensates for the problems that are
mentioned above.
DETAILED DESCRIPTION
[0024] Reference will now be made in detail to embodiments of the
present invention, examples of which are described herein and
illustrated in the accompanying drawings. While the invention will
be described in conjunction with embodiments, it will be understood
that they are not intended to limit the invention to these
embodiments. On the contrary, the invention is intended to cover
alternatives, modifications and equivalents, which may be included
within the spirit and scope of the invention as defined by the
appended claims.
[0025] According to the invention, the process for manufacturing a
thin-walled container consists in producing said thin-walled
container with a material weight/wall surface ratio on the order of
150 g/m.sup.2 to 250 g/m.sup.2, and even 150 g/m.sup.2 to 200
g/m.sup.2.
[0026] The collar weight of the package is excluded from this
ratio. The collar of the package is defined by the material that
does not undergo any deformation during the manufacturing of said
package.
[0027] In this case, the thin-walled container is of the type that
is manufactured in a known way by a longitudinal and radial blowing
process starting from a preformed shape.
[0028] This container has the necessary and desired volume, and it
is manufactured from PET.
[0029] In contrast, residual manufacturing stresses remain.
Actually, in the case of PET, in particular, once the preformed
shape is blown, the container is cooled very quickly in the molds.
The shape that is obtained and the stresses that are linked to the
deformation are created by this lowering of temperature.
[0030] Actually, during the blowing process, the stresses are
exerted in two directions, longitudinal and radial, hence the name
of bi-oriented PET container given to the containers that are thus
obtained.
[0031] This setting at a temperature that is below the glass
transition temperature is what ensures that the container retains
its shape.
[0032] The process for pressurization, according to this invention,
of a thin-walled container that is obtained according to the
preceding process, designed to contain a flat liquid, consists of
the series of the following stages:
[0033] o Production of a container according to the preceding
process, o Filling the thin-walled container, which has residual
stresses, under cold conditions with said flat liquid, o Sealing
the container after filling, and o Heating the wall of the
container, without raising the temperature of the liquid, to reach
the temperature point for release of said residual stresses so as
to generate a reduction of volume of the container and therefore a
pressurization of said container.
[0034] The purpose of this last so-called heating stage of the wall
is to heat only the wall taken in its thickness. This heat input
causes the release of stresses that had been created by the rapid
cooling after deformation during manufacturing.
[0035] In the case of a blown PET container, the residual stresses
are bi-oriented. The container therefore has a tendency to resume
its initial shape, i.e., that of the preformed shape.
[0036] Because of this tendency toward a volumetric reduction, the
interior of the container is pressurized and since the liquid is
incompressible, the head space is compressed until a balance is
reached between the pressure exerted by the wall and the inner
pressure.
[0037] The thus generated inner pressure remains less than 1 bar,
but this pressure is absolutely adequate for considerably
increasing the rigidity of the filled and sealed container before
its first sealing.
[0038] Such heating can be implemented by means of spraying hot air
on the periphery of the container for a short period of time. It is
advisable to reach the temperature point that causes the release of
the stresses in the material, a point known also under the name of
glass transition point. The heat energy input should be significant
over a very short period.
[0039] Thus, the PET, which is a poor conductor of heat, absorbs
calories supplied by hot air, which leads to a rapid release of the
stresses and prevents the transmission of calories to the liquid or
at least makes the amount of transmitted calories totally
negligible.
[0040] Actually, in the case of heating and a temperature rise of
the liquid mass that is contained, it is known that this causes, in
cooling, a reduction of the volume of the head space that is
reflected by a collapse of the bottle. Actually, the inner pressure
decreases while the container has seen its volume created, since
the release of the stresses is also created with the lowering of
the temperature below the glass transition point.
[0041] The inner pressurization according to the process of this
invention also makes it possible to compensate for the reduction in
pressure, low but able to exist, linked to the loss of a portion of
the liquid because of the permeability of the walls, these walls
being very thin.
[0042] The pressurization of the interior of the container also
makes it possible to compensate for the collapse that is linked to
a temperature decrease between the packaging temperature and the
storage temperature, before opening.
[0043] The thus used process is extremely industrializable with
very limited costs, very small breakdown risks, and an absolutely
satisfactory reproducibility since it is self-regulated.
[0044] Primarily, the rigidification processing by heat is
conducted outside of the chain, namely when the container is
sealed, which is a considerable gain by eliminating an operation
inside the aseptic chamber when the packaging is produced by
aseptic means.
[0045] The thin-walled containers that are thus produced, having
wall thicknesses such that the material weight/surface ratio is
between 150 g/m.sup.2 and 250 g/m.sup.2, and more particularly 150
g/m.sup.2 and 200 g/m.sup.2, can withstand large loads because of
their greatly increased rigidity; in particular, such containers
can be palletized, and the pallets themselves can be stacked.
[0046] From the sanitary standpoint, it should also be noted that
the guarantee of the preservation of qualities imparted to the
liquid during bottling cannot be disputed since the heating
operation is outside of the bottling chain and is implemented on a
closed container. The advantage of this outside operation is
measured when it is a matter of a chain working in an aseptic
environment.
[0047] Even a possible contamination source is eliminated since the
station that allows the pressurization of the interior of the
container is withdrawn from the working zone in an aseptic
environment.
[0048] The heating--of which it is indicated that a preferred
embodiment is that of hot air--can also resort to any other type of
heating that allows a rapid elevation of the temperature of the
wall without significantly influencing the temperature of the
contents, for example infra-red heating.
[0049] Likewise, the material in question is PET because it is
currently the most used, but this invention relates to any suitable
material for producing a container, able to exhibit residual
stresses, obtained from deformation.
* * * * *