United States Patent [19J
`Palaniappan et al.
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US006120730A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,120,730
`Sep.19,2000
`
`[54] HEAT AND HYDROGEN PEROXIDE GAS
`STERILIZATION OF CONTAINER
`
`[75]
`
`Inventors: Sevugan Palaniappan, Grayslake;
`Ronald Swank, Crystal Lake, both of
`Ill.
`
`[73] Assignee: Tetra Laval Holdings & Finance, SA,
`Pully, Switzerland
`
`5,368,828 11/1994 Carlson ................................... 422/300
`5 ,660,100
`8/1997 Spelten et a!. . ... ... .... ... ... ... ... ..... 99/356
`5,857,309
`1!1999 Cicha et a!.
`.............................. 53/167
`
`OTHER PUBLICATIONS
`
`"Easy, Handy, Economic" (The new filling machine genera(cid:173)
`tion)-Combibloc, prior art.
`"The Filling Machine Range" -Combibloc, prior art.
`
`[21] Appl. No.: 09/105,523
`
`[22] Filed:
`
`Jun. 26, 1998
`
`Int. Cl? ............................... A61L 2/20; B65B 55/10
`[51]
`[52] U.S. Cl. ............................ 422/28; 422/302; 422/304;
`53/167; 53/426
`[58] Field of Search .............................. 422/28, 302, 298,
`422/304; 53/426, 167
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,797,255
`4,944,132
`4,992,247
`5,114,670
`5,129,212
`5,178,841
`5,213,759
`5,251,423
`
`1!1989 Hatanaka eta!. ......................... 422/28
`7/1990 Carlsson eta!. ...................... 422/24 X
`2/1991 Foti ......................................... 422/304
`5/1992 Duffey ...................................... 422/24
`7/1992 Duffey eta!. ......................... 422/24 X
`1!1993 Vokins et a!. ....................... 422/304 X
`5/1993 Castberg et a!. .......................... 422/24
`10/1993 Turtschan .................................. 53/426
`
`Primary Examiner-Elizabeth McKane
`Attorney, Agent, or Firm-Welsh & Latz, Ltd.
`
`[57]
`
`ABSTRACT
`
`The present invention discloses a method and apparatus for
`sterilizing containers with gas-phase hydrogen peroxide and
`heat on a linear form, fill and seal packaging machine. A
`partially formed container is subjected to multiple applica(cid:173)
`tions of gaseous hydrogen peroxide and hot air within a
`sterilization tunnel. The sterilization tunnel is maintained at
`a temperature greater than the condensation temperature of
`hydrogen peroxide. The present invention sterilizes the
`container allowing for filling of the container with a high
`acid product such as orange juice for ambient distribution.
`The container may be any number of possibilities such as
`TETRA REX® gable top cartons, plastic bottles, and the
`like. The invention allows for the efficacious use of hydro(cid:173)
`gen peroxide gas having a concentration of up to 53%.
`
`21 Claims, 5 Drawing Sheets
`
`133a
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`U.S. Patent
`US. Patent
`
`Sep.19,2000
`Sep. 19, 2000
`
`Sheet 3 of 5
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`U.S. Patent
`US. Patent
`
`Sep.19,2000
`Sep. 19, 2000
`
`Sheet 4 of 5
`Sheet 4 0f 5
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`6,120,730
`6,120,730
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`22 \
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`150
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`
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`FIG. 4
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`
`p. E5
`
`

`

`U.S. Patent
`
`Sep.19,2000
`
`Sheet 5 of 5
`
`6,120,730
`
`HYDROGEN PEROXIDE SUPPLY
`
`r--r-~250
`
`252
`
`>-
`
`/232
`
`256 AIR
`SUPPLY
`
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`
`p. E6
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`

`

`6,120,730
`
`1
`HEAT AND HYDROGEN PEROXIDE GAS
`STERILIZATION OF CONTAINER
`
`CROSS REFERENCES TO RELATED
`APPLICATIONS
`
`Not Applicable
`
`STATEMENT REGARDING FEDERALLY
`SPONSORED RESEARCH OR DEVELOPMENT
`
`Not Applicable
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to sterilization of containers.
`Specifically, the present invention relates to an apparatus and
`method for the sterilization of containers using multiple
`applications of heat and hydrogen peroxide gas within a
`sterilization tunnel.
`2. Description of the Related Art
`Milk or juice is often packaged in containers that have
`been sterilized to prolong shelf life of the contents under
`refrigeration. When milk or juice is being packaged under
`aseptic packaging conditions, the contents are capable of
`being stored for a substantial period of time at room tem(cid:173)
`perature without spoilage. Such packaging processes require
`effective sterilization of the packaging material prior to
`filling of a container formed from the packaging material.
`For example, a container, such as a gable-top carton, that has
`previously been partially formed may have its interior
`surfaces sterilized prior to being filled with product. U.S.
`Pat. No. 4,375,145, discloses a packaging machine having a
`conveyor on which pre-formed cartons advance under ultra(cid:173)
`violet germicidal solution, such as hydrogen peroxide, pass(cid:173)
`ing under the ultraviolet lamps.
`A popular type of packaged product is an Extended Shelf
`Life ("ESL") packaged product due to the added value such
`a filled container presents to a retailer. For example, pas(cid:173)
`teurized milk processed and packaged under typical condi(cid:173)
`tions has a shelf life at four degrees Celsius of seven to
`fourteen days while the same milk processed and packaged
`under ESL conditions has a shelf life of fourteen to sixty
`days. Under ESL conditions, juice may have a shelf life of
`forty to one-hundred twenty days, liquid eggs sixty to ninety
`days, and eggnog forty-five to sixty days. Thus, ESL pack(cid:173)
`aging greatly enhances a product since it extends the time
`period that the particular product may be offered for sale to
`the consuming public. In order to have ESL filling, the filling
`system should be kept sterile in order to prevent contami(cid:173)
`nation of the product or container during filling on a form,
`fill and seal package machine.
`Many ESL machines use UV light and hydrogen perox(cid:173)
`ide. However, UV lamps greatly increase the price of a
`packaging machine and require extensive monitoring and 55
`maintenance to operate properly.
`Another problem with current sterilization practices is the
`limitation of concentration of hydrogen peroxide that may
`be used on packaging material for food. Only a minute
`quantity of hydrogen peroxide residue may be found on the
`packaging that limits most applications to less than 1%
`concentration, and requiring UV light. However, as men(cid:173)
`tioned above, UV lamps and associated components are very
`expensive and require more maintenance and energy than
`machines without UV lamps.
`Another popular type of packaged product is an aseptic
`packaged product due to the tremendous value such a filled
`
`2
`container presents to a retailer. For example, ultra high
`temperature processed milk may have a non-refrigerated
`shelf life of over one-year in a TETRA ERIK® Aseptic
`package. Such a package is fabricated from a web of
`5 packaging material on a vertical form, fill and seal packag(cid:173)
`ing machine that is substantially enclosed except for an
`outlet for the final package. It is quite apparent that produc(cid:173)
`ing a package capable of non-refrigerated distribution is
`highly desirable, however, the packaging machine must be
`10 substantially enclosed to prevent any and all contamination
`of the product, the machine or the packaging material.
`In the area of aseptic linear form, fill and seal packaging
`machines, wherein a series of container blanks are utilized
`instead of a web of packaging material, the maintenance of
`15 the entire machine in a non-contaminated enclosed environ(cid:173)
`ment is highly critical. One such machine is disclosed in
`U.S. Pat. No. 5,660,100 wherein a preheating zone, a
`sterilizing zone, a drying zone, a filling zone and a closure
`zone are all enclosed within a single sterile space that
`20 optimizes hermeticity. A hydrogen peroxide aerosol or liquid
`is utilized to sterilize the packages and the enclosure. As is
`apparent, the hermetically sealed environment is the most
`important factor in maintaining the aseptic environment.
`Such an environment increases the price of the machine and
`25 requires substantial maintenance.
`Another machine is disclosed in U.S. Pat. No. 4,992,247
`wherein a container sterilization system is adaptable to a
`form, fill and seal machine. The system is a closed loop
`system having a chamber, a blower for directing a mixture
`30 of air, vaporized hydrogen peroxide and vaporized water
`through ductwork and to a vapor delivery inlet manifold
`disposed above a line of conveyors conveyed therethrough
`the system. An exhaust manifold is positioned below the
`containers to receive the mixture. An iso-box is positioned
`35 at the front of the inlet manifold to serve as an air lock or
`curtain to prevent outside contaminants from entering the
`chamber and to prevent vaporized hydrogen peroxide from
`leaving the chamber. Containers enter the iso-box before
`entering the chamber. In the chamber, hydrogen peroxide
`40 condenses on the inner surfaces of each of the containers
`prior to exiting through another iso-box. As each container
`moves through the chamber, liquid hydrogen peroxide con(cid:173)
`denses on inner surfaces and eventually an equilibrium is
`reached between the liquid and vapor hydrogen peroxide.
`45 The pre-heating temperatures and the processing tempera(cid:173)
`tures are controlled to maintain the sterilizing effect. After
`the iso-box is a drying air inlet manifold having heated air
`flowing from a HEPA filter. Although U.S. Pat. No. 4,992,
`247 discloses that the system is positioned between a bottom
`50 forming station and a top sealing station, it is assumed that
`a filling station is disposed adjacent the drying manifold. It
`is important in U.S. Pat. No. 4,992,247 that the hydrogen
`peroxide condense on the containers in order to have the
`desired "scrubbing" effect.
`An ESL machine is capable of producing a large number
`of containers per hour of operation and allows for an "open"
`operating environment as compared to an aseptic machine
`that requires a substantially enclosed environment for most
`of the machine to prevent contamination of the packaging
`60 material, product and machinery. However, the aseptic con(cid:173)
`tainer is capable of non-refrigerated storage for long periods
`of time. In the sterilized package stage, positioned between
`ESL packages and aseptic packages, are high acid ambient
`distribution ("HAAD") packages. The HAAD package is
`65 capable of non-refrigerated storage, however, the product
`must have a minimum acidity (pH less than 4.6) such as the
`acidity of orange juice (pH 2.8) as compared to the acidity
`
`p. E7
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`

`6,120,730
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`5
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`10
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`3
`of milk (pH 6.9) which is an unacceptable product for a
`HAAD package. What is needed is a way of producing a
`HAAD container on a linear form, fill and seal packaging
`machine without major modification of the machine.
`BRIEF SUMMARY OF THE INVENTION
`The present invention provides a solution to the need for
`a machine capable of producing a HAAD container without
`major modification of a linear form, fill and seal packaging
`machine. The present inventions provides a modification to
`current ESL machines that allows for the production of a
`HAAD container without having to substantially enclose the
`entire packaging machine.
`One aspect of the present invention is a sterilization
`apparatus for use on a packaging machine. The sterilization
`apparatus has a conveyor assembly and a sterilization tunnel 15
`encompassing a portion of the conveyor assembly. There is
`a plurality of gas nozzles disposed inside the sterilization
`tunnel for emitting hydrogen peroxide gas onto each of the
`cartons as the cartons are conveyed underneath the nozzles.
`There is also a plurality of heaters for flowing heated air onto 20
`the cartons subsequent to application of hydrogen peroxide
`gas from a corresponding nozzle.
`Another aspect of the invention is a method for sterilizing
`cartons on a packaging machine. The method includes
`moving the cartons into a sterilization tunnel, applying 25
`hydrogen peroxide gas, heating the cartons, applying
`another dose of hydrogen peroxide gas, applying a third dose
`of hydrogen peroxide gas, then heating the cartons before
`moving the cartons from the sterilization tunnel.
`Yet another aspect of the invention is a packaging 30
`machine having a conveyor assembly, a sterilization tunnel
`and a filling station. The sterilization tunnel has a plurality
`of vapor nozzles and a plurality of heaters for sterilizing
`cartons being conveyed through the tunnel. At the filling
`station a high acid product is filled into each of the cartons. 35
`A slight derivation of this aspect of the invention includes a
`dual indexing processing line wherein two cartons are
`simultaneously transported by the conveyor assembly. Thus,
`each gas nozzle is divided into two sub-nozzles for applying
`hydrogen peroxide gas to both cartons simultaneously. 40
`Further, the heaters are divided and the filling station has two
`fill pipes for filling two cartons simultaneously.
`Yet another aspect of the invention is using ionized air that
`is mixed with the hydrogen peroxide gas and also ionized air
`for the heaters.
`It is a primary object of the present invention to provide
`a method and apparatus for providing a high acid ambient
`distribution product in a carton.
`It is an additional object of the present invention to
`provide a method and apparatus for sterilizing cartons on a 50
`form, fill and seal packaging machine using multiple appli(cid:173)
`cations of gaseous hydrogen peroxide and heat.
`It is yet an additional object of the present invention to
`provide a method and apparatus for sterilizing cartons using
`hydrogen peroxide gas having a concentration upwards to
`53%.
`Having briefly described this invention, the above and
`further objects, features and advantages thereof will be
`recognized by those skilled in the pertinent art from the
`following detailed description of the invention when taken 60
`in conjunction with the accompanying drawings.
`
`4
`FIG. 2 is a top perspective view of a dual line, dual
`processing packaging machine integrated with the steriliza(cid:173)
`tion apparatus of the present invention.
`FIG. 3 is a top plan view of the sterilization apparatus of
`the present invention.
`FIG. 4 is an isolated perspective view of the egress of
`sterilization tunnel of the present invention.
`FIG. 5 is an isolated view of the gas delivery system of the
`present invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`A common form of container for milk or juice is the gable
`top carton although some cartons no longer have a gable top.
`The carton has a paperboard substrate with a plastic (usually
`polyethylene) coating on the inside and the outside that
`enables the top of the carton to be closed and sealed after
`filling. Gable top cartons, standard or modified, are usually
`fabricated on a linear, multiple station, form, fill and seal
`packaging machine. An example of such a machine is the
`TR/18™ TETRA REX® packaging machine available from
`Tetra Pak, Inc. of Chicago, Ill.
`Other types of containers that are partially formed and
`have an open top before filling include, plastic bottles such
`as polyethylene terephthalate (PET) bottles and blow
`molded polyethylene bottles. Yet other types of containers
`include the TETRA TOP® package available from Tetra
`Pak.
`Referring to FIGS. 1 and 2, the sterilization apparatus 20
`is schematically shown on a packaging machine 100. The
`packaging machine may have a bottom forming station 101
`that receives the containers 50 in an erected state. The
`bottom forming station 101 will heat, fold and seal the
`bottom of the container 50 to produce an open-top container
`with sidewalls and a sealed bottom. The open top container
`50 is placed on a conveyor system 24 for conveyance at a
`predetermined interval (indexing) to the right as viewed in
`FIG. 2. The containers 50 are placed equidistant apart and
`advance a predetermined number of carton positions during
`each periodic advancing step of the conveyor. Between each
`advancing step of the conveyor 24, the containers 50 gen(cid:173)
`erally remain stationary for processing for the predetermined
`interval. The predetermined interval usually corresponds to
`45 the slowest process on the line in the fabrication of the
`carton. The slowest process is usually the sealing of the top
`of the container 50 after filling with a desired product. A
`container 50 will wait for the predetermined interval, then
`proceed toward the next station.
`The containers 50 may then proceed to an optional fitment
`applicator station 103. Other machines may not have a
`fitment applicator, or may apply the fitment post-processing.
`In such situations, the containers 50 will proceed directly to
`the sterilization apparatus 20. If a fitment is applied, various
`55 applicators may be employed. One such applicator is
`described in U.S. patent application Ser. No. 08/710,619
`filed on Sep. 20, 1996 for a Process And Apparatus For
`Applying Fitments To A Carton which is hereby incorpo(cid:173)
`rated by reference.
`The containers 50 then proceed to the sterilization appa-
`ratus 20. The sterilization apparatus 20 is positioned
`between the bottom forming station 101 and the filling
`station 103, and is generally composed of a sterilization
`tunnel 22, that encompasses a portion of the conveyor
`65 assembly 24 and a pre-folding/heating station 26. The ster(cid:173)
`ilization tunnel has a series of hydrogen peroxide gas
`stations and heater/hot air stations disposed above the con-
`
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWINGS
`FIG. 1 is a schematic side view of the conveyor line of a
`packaging machine integrated with the sterilization appara(cid:173)
`tus of the present invention.
`
`p. E8
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`6,120,730
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`5
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`20
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`5
`veyor assembly 24 to perform several actions on each
`container 50 as it is conveyed below. The tunnel 22 has an
`ingress 38 from which containers 50 enter, and an egress 40
`from which containers 50 exit the tunnel 22. The ingress 38
`and egress 40 are open to the packaging machine 100 that
`may be closed on its sides for safety, however, it has an open
`top which is in unobstructed flow with the environment.
`The containers 50 are conveyed to a pre-folding/heater
`station 26. At the station 26, each container 50 is heated to
`a first pre-determined temperature to prepare the container
`50 for application of hydrogen peroxide gas. As shown in the
`examples below (under pre-heater), the temperature varies
`from 200° C. to 300° C. At the station 26, the container 50
`may also have its top panels pre-folded if the container 50
`is a gable-top carton or the like. If, as shown in FIGS. 1 and
`2, the packaging machine 100 has a dual processing line
`wherein two containers 50 are simultaneously processed at
`each station, then the heating station 26 will have dual hot
`air blowers 107 and 109 with corresponding pre-folding
`arms 111.
`In an alternative embodiment not shown, the heater sta(cid:173)
`tion 26 may be placed within the tunnel 22. If the heating
`station 26 is within the tunnel 22, the open area 37 will be
`occupied by a hydrogen peroxide gas station or a heater.
`After the pre-heating at the heating station 26, the con(cid:173)
`tainers 50 are conveyed through the ingress 38 and into the
`sterilization tunnel 22. The first station inside of the tunnel
`22 is the first hydrogen peroxide gas station 28. At the first
`hydrogen peroxide gas station, each container 50 is sub(cid:173)
`jected to a quantity of gas phase hydrogen peroxide emitted
`from a gas nozzle 63 and 64 at approximately 190° C. The
`gas nozzles 63 and 64 continuously emit gas phase hydrogen
`peroxide at a predetermined rate as opposed to intermittent
`spraying of the gas in each container as each container 50
`pauses at the vaporization station 28. On high production
`machines (e.g., over 10,000 containers per hour), such
`intermittent spraying would be impractical. A preferred
`pre-determined rate is 0.5 liters per hour.
`Immediately after the first hydrogen peroxide gas station
`28 is the first interior heating station 34. Hot air is blown
`from blower tubes 113 onto each container 50 as it passes
`below. The temperature of the heated air may vary from 150°
`C. to 350° C. Immediately after the first interior heater
`station 34 is the second hydrogen peroxide gas station 30.
`Similar to the first hydrogen peroxide gas station 28, the
`second hydrogen peroxide gas stations 30 subjects each
`container 50 to a quantity of gas phase hydrogen peroxide
`continuously emitted from a gas nozzle 65 and 66 at
`approximately 190° C. After the second hydrogen peroxide 50
`gas station 30 is an open area 37, open in that there is no
`action performed on the containers 50 at this "station".
`However, in other embodiments, the open area 37 may have
`an optional heater station similar to the first interior heater
`34.
`The next station is the third hydrogen peroxide gas station
`32. Similar to the first and second hydrogen peroxide gas
`stations 28 and 30, the third hydrogen peroxide gas stations
`32 subjects each container 50 to a quantity of gas phase
`hydrogen peroxide continuously emitted from a gas nozzle 60
`67 and 68 at a temperature of approximately 190° C.
`Subsequent to the third hydrogen peroxide gas station 32
`and just before the egress 40 to the tunnel 22, is a second
`interior heater 36. Similar to the first interior heater 34, hot
`air is blown from blower tubes 113 onto each container 50
`as it passes below. The temperature of the heated air may
`vary from 200° C. to 300° C. The heaters 34 and 36 act to
`
`6
`remove hydrogen peroxide that is applied onto each con(cid:173)
`tainer 50. The multiple hydrogen peroxide gas application
`followed by hot air removal thoroughly sterilizes the con(cid:173)
`tainers to provide an adequate log reduction of microorgan-
`isms for fabrication of a HAAD package/product, as dem(cid:173)
`onstrated by the examples below.
`As mentioned previously, the filling station 102 is subse(cid:173)
`quent to the tunnel22. The filling station may be partitioned
`by filling station walls 133a-b in order to maintain the
`10 hygienic environment during filling. To that end, a micro(cid:173)
`filtrated air system with High Efficiency Particulate Absolute
`("HEPA") filters is provided in the filling station 102. A
`filling station with such a microfiltrated air system is dis(cid:173)
`closed in co-pending U.S. patent application Ser. No.
`15 08/828,931, filed on Mar. 28, 1997, entitled Filling Machine
`Having A Microfiltrated Air Supply System, and hereby
`incorporated in its entirety by reference. The HEPA air from
`the filling station 102 flows into the egress 40 of the tunnel
`22 thereby providing sterile air into the tunnel 22 and
`directing the flow of air outward from the ingress 38 of the
`tunnel 22 to prevent contaminated air from flowing into the
`ingress 38 and ultimately into the tunnel 22. Further down(cid:173)
`line from the filling station 102 is an optional pre-breaking
`station for the top of the carton, if pre-breaking is not
`25 accomplished at the pre-heating station 26, and a top sealing
`station 104 for sealing the top of the containers 50.
`An exhaust system 41 may be disposed near the ingress 38
`with exhaust inlet 43 positioned for receiving air from the
`ingress 38 of the tunnel 22. In this manner, the flow of air
`30 through the tunnel 22 is directed towards the ingress 38.
`As shown in FIG. 4, the tunnel22 is generally composed
`of a ceiling 150, a first side wall152, a second side wall154
`and a floor 156. The portion of the conveyor assembly 24
`that transports containers 50 through the tunnel 22 is in fact
`35 itself encompassed within the tunnel 22. The tunnel 22 is
`usually composed of stainless steel to promote hygiene. The
`tunnel acts as an extension of the hygienic zone of the filling
`station 102 and top sealing station 104 in that a sterile
`environment is maintained within the tunnel 22 in an area
`40 that usually would be subject to some contamination. The
`tunnel is maintained at a temperature that inhibits conden(cid:173)
`sation of the hydrogen peroxide gas. The condensation
`temperature for hydrogen peroxide at atmospheric pressure
`is 60° C. A preferred temperature for the tunnel 22 is 140°
`45 c.
`FIG. 5 shows the gas delivery system of the present
`invention. The gas delivery system is the same for each of
`the hydrogen peroxide gas stations 28, 30 and 32. The gas
`delivery system consists of the gas nozzles and the vaporizer
`232. The vaporizer 232 may be a heat exchanger 250 that
`receives air and hydrogen peroxide through a conduit 252.
`The conduit 252 is in flow communication with a hydrogen
`peroxide source 254 and an air supply 256. As the liquid
`solution of hydrogen peroxide enters the chamber 258 of the
`55 vaporizer 232, it is heated to a temperature in excess of 175°
`C., the vaporization temperature of hydrogen peroxide. In an
`alternative embodiment, the vaporizer may transform the
`solution of hydrogen peroxide into gas through increasing
`the pressure instead of the temperature.
`The gas phase hydrogen peroxide flows through a second
`conduit 259 to the nozzles 63 and 64, in FIG. 5, where it is
`applied onto a container 50 as illustrated by arrows 260. The
`nozzles may have a distribution of openings 277 sufficient to
`widely disperse the gas. When the gas exits the nozzles 63
`65 and 64, its temperature is usually 180-190° C. The flow of
`hydrogen peroxide is continuous, and varies in the range of
`0.25 liters to 1.0 liters per hour.
`
`p. E9
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`

`6,120,730
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`
`8
`sterilization apparatus and method. The test organism for all
`of the Examples was Bacillus subtilis var niger.
`The positive controls establish the baseline of contami(cid:173)
`nation for each of the examples. For a positive control test,
`the inoculated containers are processed through a linear
`packaging machine without any form of sterilization. Thus,
`each container is not pre-heated, or vaporized or provided
`with hot air removal. Each container is only placed on the
`conveyor chain from a bottom forming station, and con(cid:173)
`veyed through the sterilization tunnel, without filling or top
`sealing.
`The air pressure of the heated air may vary from 1 inch to
`12 inches on a water column.
`15 Shake Recovery Method
`This method is used as a recovery method when the entire
`inside of the carton needs to be sampled.
`1. All test procedures performed under a laminar flow hood.
`2. Aseptically add 100 ml of sterile rinsing fluid (0.1%
`peptone, 0.05% Tween 80 and DI water) and sterile glass
`beads.
`3. Clamp carton securely at the top with vice grips and shake
`as follows:
`Shake 10 times up and down
`Rotate Y2 turn
`Shake 10 times up and down
`Turn carton side ways
`Shake 10 times side to side
`Rotate Y2 turn
`Shake 10 times side to side
`Turn carton up right
`Shake 10 times up and down
`Rotate Y2 turn
`Shake 10 times up and down
`4. Remove sample and plate appropriate dilutions
`Test Samples: Plate dilution 10-1 (10 ml in 15x150 mm
`plate) and 10-2 (1 ml in 15x100 mm plate) in duplicate
`, 10-4
`, and 10-5 in
`Positive Controls: Plate dilutions 10-3
`duplicate.
`Negative Controls: Plate the 10-1 dilution (10 ml in
`15x150 mm plate) in duplicate.
`5. Pour plates using Plate Count Agar and incubate at 32° C.
`for 48 hours.
`6. After incubation, record all results.
`
`45
`
`7
`The hydrogen peroxide gas enters and flows onto the
`opened interior 264 of the container 50, the exposed exterior
`of the container 50, and also on an optional fitment 262. As
`previously stated, the container 50 is stationary for the
`predetermined interval at each hydrogen peroxide gas sta-
`tion during which a predetermined amount of hydrogen
`peroxide gas flows onto the containers 50. For example, the
`predetermined interval may be 1.2 seconds. After applica(cid:173)
`tion of hydrogen peroxide gas, the container 50 is subject to
`hot air at the heaters 34 and 36. Obviously, if the open area 10
`37 is not used for a heater, then application of hydrogen
`peroxide gas at hydrogen peroxide gas station 30 is not
`followed by hot air application. The hot air distributes the
`hydrogen peroxide gas from the interior of the container 50
`to the exterior.
`Of the greatest importance in practicing this present
`invention are the temperature of the hydrogen peroxide gas,
`the temperature of the air from the heaters, the temperature
`of the tunnel and the concentration of the hydrogen perox(cid:173)
`ide. Although the hydrogen peroxide is set forth as a 20
`concentration, for example 35%, the flow rate of hydrogen
`peroxide may be viewed as a mass to take into account the
`pressure variations as the gas flows into the tunnel 22 from
`the gas delivery system 232. For example, a hydrogen
`peroxide flow rate of 0.5 liters per hour corresponds to 300 25
`grams of hydrogen peroxide per kilogram of air. The present
`invention contemplates upwards to 500 grams of hydrogen
`peroxide to kilogram of air.
`The present invention will be described in the following
`examples which will further demonstrated the efficacy of the 30
`novel method and apparatus for sterilizing containers on a
`linear packaging machine, however, the scope of the present
`invention is not to be limited by these examples.
`All of the examples used one-liter TETRA REX® gable
`top cartons composed of a paperboard material coated on 35
`both surfaces with a thermoplastic such as polyethylene. The
`cartons may also have a barrier layer such as an aluminum
`layer.
`Each carton sample was inoculated by spraying the micro- 40
`organism onto the interior of the cartons and allowing the
`cartons to dry overnight. The cartons were in the folded and
`longitudinal side sealed blank form. The positive controls set
`forth the amount of colony forming units (CFU) of micro(cid:173)
`organism. The log average is 6.64 per carton.
`The carton samples where run on a TETRA REX® TR/8
`model linear dual line form, fill and seal packaging machine.
`The production speed was approximately 10,000 cartons per
`hour. The cartons were placed in a magazine, open and
`erected on a carton opener, bottom formed on a mandrel and 50
`placed on a conveyor for conveyance to the sterilization
`apparatus. The cartons were not filled with a product or top
`sealed. After sterilization, the sterilized cartons were placed
`in an airtight container and transported to a laboratory for
`analysis using the Shake Recovery Method set forth below. 55
`For each of the examples, the gas phase hydrogen per(cid:173)
`oxide had a concentration of 35%. As listed in the Tables, the
`"Pre-Heater" or "Heater #1" corresponds to heating station
`26, as shown on FIG. 1. The "Heater #2" corresponds
`heating station 34. The "H202 #1" corresponds to hydrogen
`peroxide gas station 28. The "H202 #2" corresponds to
`hydrogen peroxide gas station 30. The "H202 #3" corre(cid:173)
`sponds to hydrogen peroxide gas station 32. The "Heater #3"
`corresponds heating station 36. The chamber temperature is
`indicative of the temperature of the sterilization tunnel 22.
`The log reduction corresponds to the amount of micro(cid:173)
`organisms killed and demonstrates the effectiveness of the
`
`EXAMPLE ONE
`
`For Example One, four different variables of the apparatus
`and method are set forth in Tables two through five. Table
`One illustrates the results for the Positive Control for
`Example One.
`
`TABLE ONE
`
`Positive
`Controls
`
`Result
`1
`
`4.10E+
`06
`5.50E+
`06
`5.60E+
`06
`
`Result
`2
`
`4.00E+
`06
`5.30E+
`06
`4.20E+
`06
`
`Sample
`#
`
`Variable
`
`2
`
`3
`
`PC
`5/1/98
`PC
`5/1/98
`PC
`5/1/98
`
`CFU/Carton
`
`Log
`
`4050000
`
`6.61
`
`5400000
`
`6.73
`
`4900000
`
`6.69
`
`60
`
`65
`
`p. E10
`
`

`

`9
`
`TABLE ONE-continued
`
`6,120,730
`
`10
`
`Sample
`#
`
`4
`
`5
`
`Variable
`
`PC
`5/1/98
`PC
`5/1/98
`
`Positive
`Controls
`
`Result
`1
`
`4.30E+
`06
`3.20E+
`06
`
`Result
`2
`
`3.50E+
`06
`4.70E+
`06
`
`5
`
`CFU/Carton
`
`Log
`
`3900000
`
`6.59
`
`3950000
`
`6.60
`
`10
`
`Average
`Stdev
`
`6.64
`0.06
`
`Air Velocity for Heaters ~ 470 wherein 499 ~ 17" on a water column.
`Residual Levels ~ 0.1-0.3
`
`TABLE TWO
`
`Variable A:
`
`Pre-
`Heater
`
`3
`2
`Heater H202
`#2
`#1
`
`4
`H202 #2
`
`5
`Open H202 #3
`
`7
`Heater #3
`
`Tunnel
`Temp.
`
`OFF
`
`250 c
`
`190 c
`Results:
`
`190 c
`
`190 c
`
`250 c
`
`Sample
`#
`
`Variable
`
`Result Result
`1
`2
`
`CFU/Carton
`
`Log
`
`Log Red.
`
`A1
`A2
`A3
`A4
`AS
`
`A
`A
`A
`A
`A
`
`500
`480
`310
`180
`30
`
`5