U.S. patent application number 12/660767 was filed with the patent office on 2010-09-09 for method and device for manufacturing and filling thin-walled beverage containers.
This patent application is currently assigned to KRONES AG. Invention is credited to Jochen Hirdina.
Application Number | 20100225030 12/660767 |
Document ID | / |
Family ID | 42282096 |
Filed Date | 2010-09-09 |
United States Patent
Application |
20100225030 |
Kind Code |
A1 |
Hirdina; Jochen |
September 9, 2010 |
Method and device for manufacturing and filling thin-walled
beverage containers
Abstract
A method for manufacturing and filling beverage containers (12)
having thin walls and/or at least partially unstable shapes under
the influence of heat is described, in which the containers (12)
are manufactured by blow molding of preforms (10), then filled with
a hot liquid filling product (16), next pressurized by a compressed
gas (18), and then sealed. The preforms (10) and the containers
(12) molded therefrom are pressurized during blow molding at a blow
molding temperature, which is essentially below 110.degree. C.
Inventors: |
Hirdina; Jochen;
(Regensburg, DE) |
Correspondence
Address: |
Davidson, Davidson & Kappel, LLC
485 7th Avenue, 14th Floor
New York
NY
10018
US
|
Assignee: |
KRONES AG
Neutraubling
DE
|
Family ID: |
42282096 |
Appl. No.: |
12/660767 |
Filed: |
March 4, 2010 |
Current U.S.
Class: |
264/524 ;
425/524 |
Current CPC
Class: |
B29C 2049/4608 20130101;
B29K 2667/003 20130101; B67C 3/225 20130101; B29C 49/12 20130101;
B67C 2003/227 20130101; B29C 49/4273 20130101; B29C 49/4823
20130101; B29L 2031/7158 20130101; B67C 3/045 20130101; B67C 3/14
20130101; B29C 49/46 20130101 |
Class at
Publication: |
264/524 ;
425/524 |
International
Class: |
B29C 49/00 20060101
B29C049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2009 |
DE |
10 2009 011 583.8 |
Claims
1. A method for manufacturing and filling beverage containers
having thin walls and/or at least partially unstable shapes under
the influence of heat, comprising: blow molding performs to form a
container, the performs and containers molded therefrom pressurized
during blow molding at a blow molding temperature below 110.degree.
C.; filling the container with a heated liquid filling product;
pressurizing the filled container with a compressed gas; and
sealing the filled and pressurized container.
2. The method as recited in claim 1 wherein the blow molding
temperature is below 100.degree. C.
3. The method as recited in claim 2 wherein the blow molding
temperature is in a range of approximately 80.degree. C. to
100.degree. C.
4. The method as recited in claim 3 wherein the blow molding
temperature is in a range of 80.degree. C. to 90.degree. C.
5. The method as recited in claim 1 wherein a blow mold has a
liquid temperature-regulating medium flowing through the blow mold
via a duct system.
6. The method as recited in claim 5 wherein the
temperature-regulating medium is water.
7. The method as recited in claim 1 wherein the containers, which
are still hot after the blow molding operation, are cooled on a
conveyance path to the filling operation.
8. The method as recited in claim 1 wherein the containers are sent
directly to the filling operation after blow molding.
9. The method as recited in claim 1 wherein at least some
individual containers are stored temporarily in a buffer storage at
least from time to time before filling and after blow molding.
10. The method as recited in claim 1 wherein the containers are
blown, conveyed, and filled with the hot liquid through design
and/or structural integration of a blow molding station with a
downstream filling station.
11. The method as recited in claim 1 wherein the containers are
treated and drawn during the blow molding operation by a
liquid-cooled and/or liquid-rinsed drawing rod or by a gas-cooled
and/or gas-purged drawing rod.
12. The method as recited in claim 11 wherein liquid or gas escapes
on an end face of the drawing rod directed toward a bottom of the
container to be molded.
13. The method as recited in claim 1 wherein the compressed gas is
nitrogen.
14. The method as recited in claim 1 wherein the liquid filling
product is filled into the container at a temperature above
60.degree. C.
15. The method as recited in claim 14 wherein the liquid filling
product is filled into the container at a temperature above
75.degree. C.
16. The method as recited in claim 1 wherein the filling pressure
when the compressed gas is introduced is more than 2 bar.
17. The method as recited in claim 1 wherein the containers are PET
bottles or containers having a low thermal stability.
18. A container processing device for molding and/or manufacturing
beverage containers having thin walls and/or at least partially
unstable shapes under the influence of heat and for sterile filling
with a heated liquid filling product, the container processing
device comprising: a container molding station for molding preforms
to form beverage containers by a blow molding method; a container
filling station for filling the containers with a heated liquid
filling product; a gassing station for pressurizing the filled
containers with a compressed gas; and a sealing device for
pressure-tight and airtight sealing of the containers, the
container molding station being formed by a blow molding station
for stretch blow molding to form the plastic beverage containers,
the blow molding station including a blowing mold having a duct
system for a temperature-regulating medium to flow through, the
temperature-regulating medium being water.
19. The device as recited in claim 18 wherein the container molding
station and the container filling station are spatially and/or
structurally integrated or combined.
20. The device according to claim 18 wherein the blow molding
station has a liquid- or gas-cooled drawing rod, an opening for the
escape of liquid or gas being situated on an end face of the
drawing rod facing a bottom of the container to be molded.
21. The device as recited in claim 18 wherein the device is a
rotary machine for continuous container molding and container
bottling in an integrated process.
Description
[0001] This claims the benefit of German Patent Application DE 10
2009 011 583.8, filed Mar. 6, 2009 and hereby incorporated by
reference herein.
[0002] The present invention relates to a method and a device for
manufacturing and filling beverage containers having thin walls
and/or at least partially unstable shapes under the influence of
heat.
BACKGROUND
[0003] In sterile bottling of beverages, it is known that the air
present in the head space of the beverage container may be
displaced, e.g., by introducing liquid nitrogen, as is known from
EP 0 481 019 B1, for example. Adding liquid nitrogen largely
displaces the total atmospheric oxygen present in the container,
thereby achieving better shelf life of the beverage.
[0004] In hot bottling of beverages in PET containers, the thermal
stability of the material and the vacuum stability of the container
also constitute a challenge, which is met through various measures.
Because of the low glass transition point of approximately
75.degree. C., the thermal stability of PET is not sufficient for
filling temperatures of sensitive products, which are usually
bottled in temperature ranges between 85.degree. C. and 92.degree.
C. Therefore, the material must usually be thermally crystallized
in processing in the stretch blow molding machine. This is
implemented by a high temperature of the processed preforms
(so-called preform temperature) and heated blow molds (120.degree.
C. to 160.degree. C.). However, this results in much higher energy
consumption because in these methods, additional cooling of the
container by compressed air is necessary before unmolding. Another
disadvantage is the limited output performance due to the required
crystallization time in the mold.
[0005] Compensation for the volume shrinkage of the filling product
due to cooling may be implemented by a relatively complex bottle
design, such as that known from WO 2006/062829 A2, for example.
These bottles, which are suitable for hot bottling containers, are
much heavier in comparison with conventional designs for cold
bottling containers, are more complex to manufacture, and thus are
also much more expensive. However, in view of the high cost of raw
materials, which will continue to rise in the future, it is
becoming increasingly less economical to achieve the advantages of
hot bottling by way of a higher bottle weight. Furthermore, bottles
having vacuum equalizing surfaces are more difficult to label and
in some cases have a definitely reduced stackability.
[0006] For this reason, JP 06 263 190 A describes a method for hot
filling of thin-walled containers, in which the container stability
after the cooling phase is to be ensured by introducing liquid
nitrogen, because its expansion counteracts the shrinkage process
due to the cooling of the container contents.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide a process
sequence for container manufacturing and filling, which will ensure
an improved energy-efficient method of providing filled beverage
containers in the most reliable possible manner starting from a
preform, to its blow molding to form a beverage container and then
to hot filling. One primary focus of attention is to ensure the
least possible deviation in shape from the blow-molded container
contour as a result of the subsequent filling and cooling of the
container and of the filling product in the container.
[0008] The present invention provides a method for manufacturing
and filling beverage containers having thin walls and/or at least
partially unstable shapes under the influence of heat, in
particular PET bottles or similar containers having a low thermal
stability, the containers being manufactured by blow molding of
preforms, then filled with a hot liquid filling product (16), next
pressurized by a compressed gas (18) and then sealed, by exposing
the preforms and the containers molded therefrom to a blow molding
temperature essentially below 110.degree. C. during blow molding.
It is advantageous in particular when the blow molding temperature
is essentially below 100.degree. C. In numerous experiments,
temperatures in a range of 80.degree. C. to 90.degree. C. in blow
molding have proven to be practical in particular. After blow
molding, the containers and in particular the container bottoms are
cooled before transporting the containers to the filling machine.
The containers are cooled to approximately a typical ambient
temperature (approximately room temperature or below). In order for
the bottles not to shrink excessively after cooling of the
hot-filled liquid filling product, the containers are exposed to
nitrogen after filling. Furthermore, care is taken to ensure that
the blow molding temperature is below 110.degree. C., preferably
between 60.degree. C. and 95.degree. C. and most preferably between
80.degree. C. and 90.degree. C.
[0009] In a preferred variant of the method according to the
present invention, liquid temperature-regulating medium flows
through the blow mold via a duct system. For this
temperature-regulating medium, essentially water may be used if the
blow molding temperature is not above 100.degree. C. The blow mold
is usually connected by hose lines to a central distributor at the
center of the blow molding machine. A network of bores through
which the temperature-regulating medium flows passes through the
blow mold. Each of the two blow molds (per blow molding station)
has two connections for the forward flow and return flow of the
medium. According to the present invention, this medium transfers
heat to the blow mold in this large-area bore labyrinth in a
temperature range below 110.degree. C. The bottom of the blow mold
normally has separate connections for a second circuit at a
different temperature. The bottom temperature is preferably less
than 30.degree. C., preferably less than 10.degree. C., if
possible.
[0010] A special advantage of the method according to the present
invention is that the method may be performed at temperatures below
100.degree. C. using water as the temperature-regulating medium for
the blow molding rather than oil at 130.degree. C. to 140.degree.
C., as is customary in the known related art. In other words, it is
advantageously possible to work with water instead of oil as the
temperature-regulating medium.
[0011] A traditional so-called hot-fill method works with blow
molding temperatures of approximately 130.degree. C. and filling
product temperatures of approximately 90.degree. C. The drawn PET
is then pressed against the hot mold wall during the blow molding
operation to remove stresses from the material, so that after the
subsequent contact with the hot filling product at a later time,
the PET bottle is unable to shrink back into the undrawn preform.
Because of the material structure thereby formed, it is also
possible to speak of low-stress PET.
[0012] In contrast with these methods known from the related art,
the present invention allows only a maximum blow molding
temperature of 110.degree. C., preferably of approximately
80.degree. C. to 90.degree. C. (at a filling product temperature of
also approximately 90.degree. C.), so that inherent stresses remain
in the drawn PET to allow better compensation for the subsequent
pressurization with nitrogen.
[0013] It may also be advantageous to send the containers to the
filling operation immediately after the blow molding operation
without an intermediate buffer or interim storage. The purpose of
this is primarily to establish largely the same conditions
(moisture uptake, cooling) for all bottles and/or containers. In
other words, no buffer is used between the blow molding machine and
the filling machine, but instead each bottle is transferred to the
filling machine in the same time period. The bottles are preferably
kept with the same spacing in this temporarily stored conveyance
system. The constant conveyance time between the blow molding
machine and the filling machine could not be guaranteed when using
a buffer.
[0014] The method according to the present invention has the
particular advantage that the bottle quality is kept at a very
constant level because the same extent of shrinkage and thus always
constant filling levels are largely ensured. Furthermore, combining
the steps of container molding and container filling structurally,
in time and in terms of process engineering, as is preferred but is
not absolutely necessary, has the advantage that all parameters
important for a satisfactory procedure are much more easily kept
constant and/or may be influenced more easily in the desired manner
than is the case with the traditional method.
[0015] The method according to the present invention is used for
filling beverage containers having thin walls and/or at least
partially unstable shapes under the influence of heat, e.g., of PET
bottles or similar containers having a low thermal stability with a
hot liquid filling product, which is bottled in the containers,
after which these containers are pressurized by a compressed gas
and then sealed. According to the present invention, the containers
are sent to the filling operation after a blow molding operation,
so that the containers, which are still hot after the blow molding
operation, may be sent to the filling operation without any major
delay, using a conveyance system in which the bottles are cooled,
if necessary. The containers are therefore blown, conveyed, and
filled with the hot liquid within short distances, in particular
through design and/or structural integration of a blow molding
station with a downstream filling station.
[0016] According to one embodiment variant of the method according
to the present invention, the containers are treated and drawn with
the aid of a liquid-cooled drawing rod during the blow molding
operation. The containers may optionally be treated and drawn with
the aid of a drawing rod, which is gas cooled and/or through which
gas flows during the blow molding operation. It is preferable here
for a liquid or gas outlet to be provided essentially on an end
face of the drawing rod facing the bottom of the container to be
molded. Essentially the bottom of the container is cooled in this
way; the side walls should also be largely cooled but a cold bottom
is more important.
[0017] The method may provide for gaseous or liquid nitrogen to be
used as the compressed gas for acting upon the filled containers.
The nitrogen ensures that no partial vacuum exists in the
containers after cooling, so the relatively thin-walled and/or
bendable containers are not deformed by the vacuum in an
undesirable manner.
[0018] The filling product is typically filled into the container
at a temperature above 60.degree. C., in particular at a
temperature above 75.degree. C. The method according to the present
invention is suitable in particular for filling temperatures of the
liquid filling product between approximately 80.degree. C. and
95.degree. C., in particular between approximately 85.degree. C.
and 92.degree. C. The filling pressure of the compressed gas
introduced after filling the container with liquid filling product
may be approximately 2 bar or more, so that the internal pressure
of the cooled containers is still greater than the ambient
atmospheric pressure at a filling product temperature of less than
4.degree. C., which corresponds to storage of the bottle in a
refrigerator.
[0019] Another goal of the present invention is to make available a
device for manufacturing and filling containers, which is able to
ensure an improved method of providing filled beverage containers
in the most energy-efficient and reliable way possible from a
preform by blow molding to form a beverage container, which is then
hot filled.
[0020] This goal is achieved with a device having the features of
independent claim 18. The present invention relates to a container
processing device for molding and/or manufacturing beverage
containers having thin walls and/or at least partially unstable
shapes under the influence of heat, e.g., PET bottles or such
containers having a low thermal stability and also for sterile
filling thereof with a hot liquid filling product. The container
processing device includes at least one container molding station
for molding preforms to form beverage containers by a blow molding
method, a container filling station for filling the containers with
hot filling product, a gassing station for pressurizing the filled
containers with a compressed gas, and a sealing device for
pressure-tight and airtight sealing of the containers. According to
the container processing device according to the present invention,
the container molding station is formed by a blow molding station
for stretch blow molding of the preforms to form plastic
containers, the blow molding station including a blow mold having a
duct system for a temperature-regulating medium to flow through,
the temperature-regulating medium being formed essentially by
water. The blow mold may be connected by hose lines, for example,
to a central distributor at the center of the blow molding machine.
A network of bores, through which the temperature-regulating medium
flows, passes through the blow mold. Each of the two blow molds
usually present per blow molding station has two connections for
forward flow and return flow of the medium. In this large-area bore
labyrinth, this medium transfers heat to the blow mold, namely in a
temperature range of less than 110.degree. C., preferably less than
100.degree. C. The bottom normally has separate connections for
another temperature-regulating medium circuit at another
temperature. The bottom temperature may preferably be less than
30.degree. C. when cold, more preferably less than 10.degree. C. A
particular advantage of this embodiment is that with the device
according to the present invention, it is possible to work with
water as the temperature-regulating medium for the blow molds at
temperatures below 100.degree. C., whereas in the related art, only
oil may be used as the temperature-regulating medium at
temperatures of 130.degree. C. to 140.degree. C.
[0021] According to one embodiment variant of the device according
to the present invention, the container molding station and the
container filling station are integrated in design and/or
structure. With the device according to the present invention, the
container molding station is preferably formed by a blow molding
station for stretch blow molding of the preforms to form plastic
containers, the container filling station, which is combined with
it in space and/or design, being connected thereto.
[0022] In another embodiment variant of the container processing
device according to the present invention, the blow molding station
has a liquid-cooled or gas-cooled and/or gas-purged drawing rod, an
opening to the liquid or gas outlet being situated essentially on
an end face of the drawing rod facing the bottom of the container
to be molded.
[0023] The device according to the present invention may be
designed in particular as a rotary machine for continuous container
molding and container filling in one integrated process.
[0024] The present invention provides a method for hot bottling,
which has been improved and developed further in essential aspects
in comparison with the known methods. Hot bottling still takes
place in a typical temperature range, which should usually be
between approximately 85.degree. C. and 92.degree. C. To compensate
for the volume shrinkage occurring in cooling of the hot-filled
liquid, the method operates with pressurization. Pressurization is
currently achieved by adding nitrogen because in numerous
experiments with PET bottles, such nitrogen pressurization has
proven to be particularly advantageous. The improved process
technology of hot filling with pressurization makes it possible to
revise the process engineering to be employed in hot bottling in
some aspects, thereby providing novel variants. The result is a
novel method claim for stretch blow molding and filling technology.
To compensate for or diminish the reshrinkage effects occurring in
the drawn PET at the filling temperature, in the method according
to the present invention, the container is stabilized by
pressurization, not by thermal crystallization of the bottle. This
means that pressurization is also utilized for mechanical
stabilization in addition to volume compensation. This has the
advantage that thermal crystallization of the material is no longer
necessary and it is possible to work with conventional blow molding
technology. The present invention relates to the manufacture of
containers, e.g., PET bottles, as well as their filling. The PET
bottles are hot filled and pressurized, with the blow molding
temperature typically to be set between 10.degree. C. and
110.degree. C., preferably 60.degree. C. and 95.degree. C., and
most preferably between 80.degree. C. and 90.degree. C. A preferred
temperature range is 80.degree. C. to 90.degree. C.
[0025] If working with a buffer for the blow-molded containers
between the blow molding station and the filling station, it may be
advantageous to discharge such containers whose dwell time in the
buffer is too long because if the dwell time is too long, too much
internal stress in the PET is dissipated, but this is a
disadvantage and should be avoided in the present context in the
interest of the least possible shrinkage of the filled bottles
which are exposed to gas and are cooling.
[0026] Finally, it should be pointed out that through the
structural integration of the individual container processing
stations and through the method steps defined by the present
invention, particularly good suitability for sterile bottling of
beverages in these containers is achieved.
[0027] Additional features, goals and advantages of the present
invention are derived from the following detailed description of a
preferred specific embodiment of the present invention, which is
given as a nonrestrictive example and refers to the accompanying
drawings. The same components here have the same reference numerals
in principle and will not be described repeatedly in some
cases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 shows a schematic flow chart to illustrate successive
method steps in hot bottling of beverage in containers.
[0029] FIG. 2 shows a schematic sectional diagram of a PET
container blow molded using a drawing rod.
DETAILED DESCRIPTION
[0030] The schematic flow chart in FIG. 1 shows successive method
steps in molding preforms to form containers and the subsequent hot
bottling of beverages in these containers. The method presented
here allows sterile filling of beverage containers and/or PET
bottles having thin walls and/or at least partially unstable shapes
under the influence of heat. These PET bottles are filled with a
hot liquid beverage, after which the bottles are pressurized by
nitrogen as a compressed gas and then sealed.
[0031] In a first method step 51, preforms 10 are molded by a blow
molding operation to form beverage containers 12, which are filled
with a hot beverage 16 in a subsequent method step S2 by a suitable
filling device 14. Containers 12, which are still hot after the
blow molding operation, are cooled in a controlled manner and then
sent to filling operation S2. Containers 12 are blown, conveyed,
and filled with hot liquid 16 within short distances, in particular
through design and/or structural integration of a blow molding
station with a downstream filling station. It may be advantageous
in this context to be sure that bottles 12 remain at the same
spacing, which is advantageous for ensuring constant filling and
shrinkage conditions. The design and/or structural integration may
also be referred to as "blocking" of the blow molding machine and
filling machine.
[0032] In a subsequent method step S3, the air in the upper area of
container 12 is displaced by filling with liquid or gaseous
nitrogen, so that the mechanical stability of container 12 may at
the same time be ensured after cooling of liquid 16.
[0033] In a subsequent method step S4, container 12, which has been
filled with hot liquid 16 and pressurized with liquid or
pressurized liquefied compressed gas 18, is sealed with a sealing
cover 20. After sealing containers 12, compressed gas 18 evaporates
slowly, while the pressure in the bottle increases. Containers 12
filled in this way may be sent to a packaging and/or storage
logistics after a cooling phase and interim storage, if
necessary.
[0034] Gaseous or liquid nitrogen (N.sub.2) in particular may be
used as compressed gas 18 in method step S3. Nitrogen ensures that
there will be no partial vacuum in containers 12 after cooling, so
that containers 12, which have relatively thin walls and/or are
soft enough to bend, do not deform in an unwanted manner due to
partial vacuum. Containers 12 are typically filled with the liquid
filling product at a temperature above 75.degree. C. The method
described here is suitable for bottling the beverage at filling
temperatures between approximately 85.degree. C. and 92.degree. C.
in particular. The filling pressure of compressed gas 18 introduced
after filling containers 12 with liquid 16 may be approximately 2
bar or more, so that the internal pressure of cooled containers 12
is slightly above the ambient atmospheric pressure.
[0035] Reference numeral 8 in FIG. 1 denotes a container processing
device, which includes the processing modules required for
implementing method steps S1 through S4 described above in a
structurally integrated manner, which is characterized by the frame
surrounding the processing modules. Container processing device 8
thus includes at least one container molding station for molding
preforms 10 to form beverage containers 12 by a blow molding method
(method step S1), a container filling station having filling device
14 for filling containers 12 with hot liquid 16 (method step S2), a
gassing station for pressurizing filled containers 12 with a
compressed gas 18 (nitrogen; method step S3), and a sealing device
for pressure-tight and airtight sealing of containers 12 using
sealing cover 20 (method step S4). According to the exemplary
embodiment of the present invention described here, the container
molding station and the containing filling station are integrated
by design and/or structurally in the manner described here, so that
containers 12 undergo a controlled cooling between the container
processing stations. This has the particular advantage that
containers 12 shrink in a precisely controllable manner, so that
largely constant fill levels may be maintained. In addition,
hygienic advantages are achieved through the structural integration
of container processing device 8 because the risk of contaminants
may be significantly reduced on the very short path between
container molding and filling.
[0036] The schematic longitudinal sectional view in FIG. 2
illustrates one embodiment variant of container molding using a
blow mold 22 and a drawing rod 24 movable along the direction of
longitudinal extent of preform 10 or container 12. Multipart blow
mold 22 has an essentially known design having at least two
shell-type halves and a bottom part 26 clampable thereto and a head
part 28, which secures preform 10 during the molding operation and
also secures finished molded container 12. As already mentioned,
with the container processing method according to the present
invention, preforms 10 or containers 12 are treated, i.e., drawn
during the blow molding operation by liquid or gas and/or with
drawing rod 24. Liquid or gas is allowed to escape essentially at
one end face 32 oriented to bottom 30 of drawing rod 24 facing
container 12 to be molded. Essentially only bottom 30 of container
12 is cooled in this way, while side walls 34 may retain the high
temperature prevailing during the blow molding operation.
[0037] The present invention is not limited to the exemplary
embodiments presented above. Instead, a plurality of variants and
modifications is conceivable, making use of the idea according to
the present invention and therefore also falling within the scope
of the present invention.
LIST OF REFERENCE NUMERALS
[0038] 8 Container processing device [0039] 10 Preform [0040] 12
Container [0041] 14 Filling device [0042] 16 Liquid, beverages
[0043] 18 Compressed gas [0044] 20 Sealing cover [0045] 22 Blow
mold [0046] 24 Drawing rod [0047] 26 Bottom part [0048] 28 Head
part [0049] 30 Bottom [0050] 32 End face [0051] 34 Side wall [0052]
S1 First method step [0053] S2 Second method step [0054] S3 Third
method step [0055] S4 Fourth method step
* * * * *