JP2013018535A - Method of sterilizing paper container for liquid and paper container for liquid using the method and sterilizer - Google Patents

Abstract

Disclosed is a radiation sterilization method in which a sleeve is sterilized in a short time, and there is no discoloration due to oxidative deterioration of a sterilized packaging material, particularly a polyethylene film, and the generation of a strange odor is reduced.
A laminated body using paperboard as a base material layer, a blank is formed, a back seal is bonded from the blank, a folded sleeve is formed, and then a rectangular cylindrical sleeve is formed, and the rectangular cylindrical shape is formed. Forming the bottom of the sleeve to form a paper container, attaching a stopper to the paper container to form a stoppered paper container, sterilizing the inner surface of the stoppered paper container with hydrogen peroxide, Aseptic method of sterilized liquid food in a stoppered paper container and sterilization of a sealed liquid paper container,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of air in the packaging bag is adjusted to 5% or less, radiation is irradiated from the outside of the packaging bag, and the sleeve is radiation sterilized by radiation. The liquid paper container sterilization method is characterized.
[Selection] Figure 4

Description

  The present invention relates to a liquid paper container sterilization method for aseptically filling liquid foods such as beverages such as mineral water, coffee and juice, and soup. In particular, it relates to a method for sterilizing a sleeve forming a liquid paper container.

  The method of aseptic filling liquid food can be filled at low temperature by filling under aseptic environment. As a result, long-term storage is possible while minimizing changes in the taste and aroma of the contents. Has the advantage.

  The basic idea of the aseptic filling method is to fill and package aseptically treated liquid food in a sterile environment using aseptically treated liquid paper containers.

  The aseptic environment is satisfied by heating the inside of the filling and packaging machine, sterilizing with a sterilizing agent, etc., and introducing clean air to shut off the outside air.

  The aseptic filling method is a liquid food in which a sterilized blank or sleeve is supplied into an aseptic filling and packaging machine in an aseptic environment, the bottom is molded and the inner surface of the paper container is sterilized with hydrogen peroxide, and then sterilized. Aseptic filling methods are widely used.

  In addition, as a method of sterilizing a blank or a sleeve, ultraviolet (UV) sterilization is used as photo sterilization, ethylene oxide gas (EOG) sterilization is used as gas sterilization, and gamma front sterilization and electron beam (EB) are used as radiation sterilization. Sterilization and hydrogen peroxide sterilization are used.

  Also, ultraviolet sterilization, which is light sterilization, has been widely used conventionally. It can be processed continuously, and there are no problems such as residual gas of ethylene oxide gas for gas sterilization and oxidative deterioration of packaging material for radiation sterilization. However, reliable sterilization in a shorter time and highly efficient sterilization in a shorter time are required.

  Among light sterilizations, there is a proposal of an aseptic filling method by pulsed light sterilization (Patent Document 1). This is an aseptic filling method in which a transparent plastic bottle made of polyethylene terephthalate resin is sterilized by pulsed light and filled with liquid food.

  In gas sterilization, ethylene oxide gas is highly toxic and has a problem of residual gas. It takes a long time to exhaust the ethylene oxide gas.

  Further, sterilization with hydrogen peroxide has a problem that hydrogen peroxide does not reach all the inner surfaces of the packaging material (sterilization unevenness). In addition, there is a problem of adsorbing to the film on the inner surface even after drying of hydrogen peroxide. In order to prevent the performance deterioration of the packaging material, there is a proposal to prevent adsorption and permeation of hydrogen peroxide (Patent Document 2).

  In this proposal, an inorganic oxide is vapor-deposited on a polyethylene terephthalate film, and a vapor-deposited film with improved gas barrier properties is laminated.

Gamma ray sterilization and electron beam sterilization, which are radiation sterilization, can be processed at room temperature. There is no sterilization unevenness and there is a feature that does not choose a packaging form. However, since the radiation itself is strong, there are problems such as discoloration of the polyethylene film of the packaging material and generation of a strange odor. In particular, a polyethylene film as a packaging material is likely to undergo oxidative degradation in the presence of oxygen in the air. In particular, ultraviolet rays, radiation, heat, etc. start. Therefore, an antioxidant is generally contained. Also, depending on the type of antioxidant, it may cause discoloration or generate a strange odor, so by performing radiation treatment in advance, confirm the discoloration and strange odor resulting from oxidation degradation, and then select the material. The current situation is.

  There is a proposal of a polypropylene composition excellent in radiation resistance, in particular, a proposal of a sheet with suppressed physical properties and discoloration after irradiation and having a less off-flavor (Patent Document 3).

  In this proposal, a propylene sheet is mixed with a phosphoric acid antioxidant, a hindered amine compound, and a stearic acid compound. This is only an effect with a propylene sheet. Polyethylene film has management problems such as blending ratio, thickness variation, and confirmation by radiation treatment in advance.

  In view of the above, a sterilization method that can sterilize a sleeve in a short time, does not cause discoloration due to oxidative deterioration of the packaging material after sterilization, particularly a polyethylene film, and generates less off-flavors is desired.

Japanese Patent Laid-Open No. 2003-72719 JP 2005-231042 A JP 2007-231036 A

  The present invention provides a radiation sterilization method in which the sleeve can be sterilized in a short time in view of the problems of the background art, and there is no discoloration due to oxidative degradation of the packaging material after sterilization, particularly polyethylene film, and the generation of off-flavors is reduced. There is to do. In particular, it is an object of the present invention to provide a method for sterilizing aseptically fillable liquid paper containers formed from sterilized sleeves.

  In order to solve the above problems, the inventors have intensively studied and completed the present invention.

The invention according to claim 1 of the present invention is a laminate in which paperboard is used as a base material layer, and at least a polyethylene layer (outer surface) / base material layer / gas barrier layer / polyethylene layer (inner surface) are sequentially laminated.
Forming a blank,
A back seal is bonded from the blank to form a folded sleeve;
Raise the sleeve, form a square cylindrical sleeve, mold the bottom of the square cylindrical sleeve to form a paper container,
A stopper is attached to the paper container to form a stoppered paper container, the inner surface of the stoppered paper container is sterilized with hydrogen peroxide, and the sterilized liquid food is sterilized in the stoppered paper container. Filling,
A method for sterilizing a sealed liquid paper container,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of the air in the packaging bags is adjusted to 5% or less,
In the liquid paper container sterilization method, radiation is applied from the outside of the packaging bag, and the sleeve is sterilized by radiation.

  The invention according to claim 2 of the present invention is the liquid paper container sterilization method according to claim 1, wherein the radiation sterilization is electron beam sterilization using an electron beam.

  The invention according to claim 3 of the present invention is the liquid paper container according to claim 1 or 2, wherein the inside of the packaging bag is subjected to vacuum suction or nitrogen substitution, or vacuum suction and nitrogen substitution. It is a sterilization method.

  In the invention according to claim 4 of the present invention, the packaging bag is composed of at least a gas barrier base material layer and a sealant layer, and the gas barrier base material layer has polyethylene deposited with any of aluminum, aluminum oxide, silicon oxide, and magnesium oxide. It is a terephthalate film, The sterilization method of the liquid paper container of any one of Claims 1-3 characterized by the above-mentioned.

  The invention according to claim 5 of the present invention is a liquid paper container formed by the sterilization method according to any one of claims 1 to 4.

The invention according to claim 6 of the present invention is a laminate in which paperboard is used as a base material layer, and at least a polyethylene layer (outer surface) / base material layer / gas barrier layer / polyethylene layer (inner surface) are sequentially laminated.
Means for forming a blank;
Means for bonding a back seal from the blank to form a folded sleeve;
Means for raising the sleeve and forming a rectangular cylindrical sleeve; and means for forming a paper container by molding the bottom of the rectangular cylindrical sleeve;
Means for forming a paper container with a stopper by attaching a stopper to the paper container; means for sterilizing the inner surface of the paper container with a stopper with hydrogen peroxide;
Means for aseptically filling the sterilized liquid food into the stoppered paper container;
A sealed liquid paper container sterilization device comprising:
After the means for forming the sleeve,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of the air in the packaging bags is adjusted to 5% or less,
A liquid paper container sterilizing apparatus comprising means for radiating radiation from the outside of the packaging bag and sterilizing the sleeve with radiation.

  In the liquid paper container sterilization method of the present invention, the sleeve for forming the liquid paper container is sterilized with an electron beam in an environment having an oxygen concentration of 5% or less. It is a sterilization method that reduces oxidative degradation of the polyethylene film in the laminate, suppresses discoloration, and reduces the generation of off-flavors. Because of sterilization by electron beam irradiation, there is no problem of residual gas and sterilization unevenness, and high-efficiency sterilization can be performed continuously in a short time. The sterilized sleeve is supplied into the aseptic filling and packaging machine, the bottom of the sleeve is molded, a liquid paper container is formed, the inner surface of the liquid paper container is sterilized with hydrogen peroxide, and the sterilized liquid food is prepared. Fill aseptically. Aseptically filled and sealed liquid paper containers are produced. This is a liquid paper container sterilization method including electron beam sterilization of a sleeve.

According to claim 1 of the present invention, a laminate in which paperboard is used as a base material layer, and at least a polyethylene layer (outer surface) / base material layer / gas barrier layer / polyethylene layer (inner surface) is sequentially laminated,
Forming a blank,
A back seal is bonded from the blank to form a folded sleeve;
Raise the sleeve, form a square cylindrical sleeve, mold the bottom of the square cylindrical sleeve to form a paper container,
A stopper is attached to the paper container to form a stoppered paper container, the inner surface of the stoppered paper container is sterilized with hydrogen peroxide, and the sterilized liquid food is sterilized in the stoppered paper container. Filling,
A method for sterilizing a sealed liquid paper container,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of the air in the packaging bags is adjusted to 5% or less,
Radiation is irradiated from the outside of the packaging bag, and the sleeve is sterilized by radiation. In the present invention, radiation sterilization is performed by irradiating an electron beam onto a sleeve for forming a liquid paper container. In particular, by performing an environment for radiation sterilization at an oxygen concentration of 5% or less, oxidative deterioration of the laminate, particularly a polyethylene layer (polyethylene film) can be reduced.

  In order to sterilize the sleeve at an oxygen concentration of 5% or less, a plurality of the sleeves are packed together and packed in a packaging bag. After adjusting the oxygen concentration of the air in the packaging bag to 5% or less, it is sealed and radiation sterilized with radiation from the outside of the packaging bag. This is possible by adjusting the oxygen concentration in the packaging bag.

In the presence of oxygen, polyethylene film accelerates oxidative degradation due to the energy of radiation. Radiation sterilization in an environment where the oxygen concentration is 5% or less can reduce the oxidative deterioration of the polyethylene film. Therefore, it is possible to reduce oxidative degradation compared to radiation sterilization in an air environment. In particular, for the off-flavor caused by oxidative degradation, volatilization of aliphatic hydrocarbons (C _{3 to} C ₁₃ ), aldehydes (C _{2 to} C ₅ ), ketones (C _{4 to} C ₈ ), and carboxylic acids (C _{2 to} C ₅ ). This is due to the generation of a sex substance. Oxidation degradation can be reduced by radiation sterilization in an environment where the oxygen concentration is 5% or less. Under an oxygen-free environment, oxidative degradation can be further reduced. In addition, when the oxygen concentration is 5% or more, the oxidative deterioration proceeds and the generation of the off-flavor component increases.

  The sterilized sleeve is supplied to an aseptic filling and packaging machine. In the aseptic filling and packaging machine, a square cylindrical sleeve is formed from the supplied sleeve, and the bottom of the square cylindrical sleeve is molded to form a paper container. A stopper is attached to the paper container to form a stoppered paper container. The inner surface of the stoppered paper container is sterilized with hydrogen peroxide and dried, and aseptically filled with the sterilized liquid food. Aseptically filled liquid paper containers are created. This is a method for sterilizing a liquid paper container capable of being aseptically filled by sterilizing a sleeve with an electron beam.

  According to claim 2 of the present invention, the radiation sterilization is electron beam sterilization using an electron beam. Radiation sterilization includes gamma ray sterilization and electron beam sterilization. Gamma-ray sterilization is possible, but gamma-ray shows high permeability, so it is easy to cause oxidative degradation of polyethylene film and other materials, and the irradiation equipment is sufficiently controlled to use cobalt 60 as a radiation source. Need to be done. Since an electron beam is emitted from an electron accelerator, management of the irradiation device is relatively easier than a gamma ray irradiation device. The penetrating power is lower than that of gamma rays. However, there is sufficient sterilizing ability at a level at which a plurality of sleeves of the present invention are sterilized. The electron beam dose is preferably 5 to 60 kGy.

  According to claim 3 of the present invention, the inside of the packaging bag is either vacuum suction or nitrogen substitution, or vacuum suction and nitrogen substitution. In order to make the oxygen concentration in the packaging bag 5% or less, it is necessary to reduce the air in the bag. What is necessary is just to suck and seal so that air may be reduced by vacuum suction. This can be done using a vacuum packaging machine. It is also possible to substitute with nitrogen. The oxygen concentration may be reduced by replacing the air with nitrogen. Moreover, you may use vacuum suction and nitrogen substitution together. An appropriate method may be determined.

According to claim 4 of the present invention, the packaging bag comprises at least a gas barrier base material layer and a sealant layer, and the gas barrier base material layer is a polyethylene on which any one of aluminum, aluminum oxide, silicon oxide, and magnesium oxide is deposited. It is a terephthalate film. The packaging bag in which the sleeve is packed is irradiated with an electron beam from the outside of the packaging bag to sterilize the sleeve. When the sealed packaging bag is stored for a number of days before being irradiated with the electron beam, oxygen in the atmosphere permeates the packaging material and enters the packaging bag. The oxygen concentration may be 5% or more. Therefore, the gas barrier base material layer is formed on the packaging bag. As the gas barrier base material layer, a polyethylene terephthalate film on which any one of aluminum, aluminum oxide, silicon oxide, and magnesium oxide is deposited can be used. A polyamide film on which any one of aluminum, aluminum oxide, silicon oxide, and magnesium oxide is deposited can also be used. A sealant layer is bonded to seal the packaging bag. As the sealant layer, a polyethylene film can be used. The packaging bag to be sealed preferably has an oxygen permeability of ² cc / m ² / day or less (measured by the JIS-K7126B method).

  According to Claim 5 of this invention, it formed by the sterilization method of any one of Claims 1-4. It is a liquid paper container formed using an electron beam sterilized sleeve. Supplying the electron beam sterilized sleeve into the aseptic filling and packaging machine, molding the bottom of the sleeve, forming a liquid paper container, sterilizing the inner surface of the liquid paper container with hydrogen peroxide, and sterilized liquid food Aseptically fill. Aseptically filled and sealed liquid paper containers are produced. A liquid paper container in which discoloration and off-flavor due to oxidative degradation of the polyethylene layer (polyethylene film) is reduced can be obtained.

According to claim 6 of the present invention, a laminate in which paperboard is used as a base material layer, and at least a polyethylene layer (outer surface) / base material layer / gas barrier layer / polyethylene layer (inner surface) are sequentially laminated,
Means for forming a blank;
Means for bonding a back seal from the blank to form a folded sleeve;
Means for raising the sleeve and forming a rectangular cylindrical sleeve; and means for forming a paper container by molding the bottom of the rectangular cylindrical sleeve;
Means for forming a paper container with a stopper by attaching a stopper to the paper container; means for sterilizing the inner surface of the paper container with a stopper with hydrogen peroxide;
Means for aseptically filling the sterilized liquid food into the stoppered paper container;
A sealed liquid paper container sterilization device comprising:
After the means for forming the sleeve,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of the air in the packaging bags is adjusted to 5% or less,
There is provided a means for radiating radiation from the outside of the packaging bag and sterilizing the sleeve with radiation. The sleeve is sterilized with an electron beam in an environment where the oxygen concentration is 5% or less, and a paper container with a stopper is formed using the sleeve, and the paper container with a stopper is further sterilized with hydrogen peroxide and filled aseptically. This is a paper container sterilizer. It is a sterilizer that reduces discoloration and off-flavor generation due to oxidative degradation of the polyethylene layer (polyethylene film).

It is explanatory drawing which shows an example of the flow of the manufacturing process of the liquid paper container of this invention. It is explanatory drawing which shows an example of the blank for forming a liquid paper container. It is explanatory drawing which shows an example of the sleeve formed by folding from the blank of FIG. It is explanatory drawing which shows an example of the state which is carrying out the electron beam sterilization of the sleeve of FIG. It is explanatory drawing which shows an example which made the sleeve of FIG. 4 the square cylindrical paper container. It is explanatory drawing which shows an example of the paper container of the state which shape | molded the bottom part of the square cylindrical paper container of FIG. It is explanatory drawing which shows an example of the paper container with a stopper which attached the stopper to the paper container of FIG. It is explanatory drawing which shows an example of the state which hydrogen peroxide sterilizes the paper container with a stopper of FIG. It is explanatory drawing which shows an example which is aseptically filled with the liquid food sterilized in the paper container with a stopper of FIG. It is explanatory drawing which shows an example of the liquid paper container (gable top type) created with the aseptic filling method of this invention. It is sectional drawing which shows an example of the laminated body of this invention. It is sectional drawing which shows an example of a packaging bag.

  Hereinafter, a form for carrying out the present invention will be described by taking a gable top type liquid paper container as an example.

  FIG. 1 is an explanatory diagram showing an example of the manufacturing flow of the liquid paper container of the present invention. A manufacturing flow 200 of the liquid paper container will be described. The blank 1 is formed from the laminated body 30, the back seal 110 is adhered to form a folded sleeve 2, the folded sleeve 2 is sterilized by electron beam, and it is supplied to an aseptic filling machine. The supplied folded sleeve 2 is raised to form a rectangular cylindrical sleeve 3, a bottom portion of the rectangular cylindrical sleeve 3 is molded to form a paper container 4, and a cap 5 is attached to the paper container 4. The stoppered paper container 6 is formed. The inner surface of the stoppered paper container 6 is sterilized with hydrogen peroxide 23, and the sterilized liquid food 10 is aseptically filled to form a sealed liquid paper container 100. Shown in a dotted frame 210 shows the steps of an aseptic filling machine.

  FIG. 2 is an explanatory view showing an example of a blank for forming a liquid paper container. FIG. 1 is a blank 1 representing the outer surface of a paper container. The blank 1 includes a back seal 110, a left panel 120, a front panel 130, a right panel 140, and a back panel 150. Each panel has a side wall C, a top B at the top of the side wall, and a bottom at the bottom. D is formed. The tops of the left panel 120 and the right panel 140 can be folded via a folding line. A top seal portion A is formed on the top portion B. Moreover, the hole F for mounting | wearing with a plug is formed in the top part.

  FIG. 3 is an explanatory view showing an example of a sleeve formed by folding from the blank of FIG. 2. The outer surface of the back seal panel 110 of the blank 1 is bonded to the inner surface of the back panel 150 to form the sleeve 2. In this state, the folded state is shown.

  FIG. 4 is an explanatory view showing an example of a state in which the sleeve of FIG. 3 is sterilized with an electron beam. The folded sleeve 2 is sealed in the packaging bag 7 in an environment having an oxygen concentration of 5% or less. This is carried into the sterilization chamber 21 where the electron beam is irradiated on the belt conveyor. The electron beam 20 uses an electron accelerator as a radiation source. The electron beam 20 is irradiated from the electron beam irradiation port 22, and the sleeve 2 is uniformly irradiated to a predetermined dose. Thereafter, the belt conveyor is carried out.

  FIG. 5 is an explanatory view showing an example in which the sleeve of FIG. 4 is a rectangular cylindrical paper container. The sleeve 2 subjected to electron beam sterilization is supplied to an aseptic filling machine installed in an aseptic environment. The folded sleeve 2 is raised by an aseptic filling machine to form a square cylindrical paper container 3. At this time, the top. The bottom is open.

  FIG. 6 is an explanatory view showing an example of a paper container in a state where the bottom of the rectangular cylindrical paper container of FIG. 5 is molded. It is the paper container 4 which shape | molded the bottom part D of the square cylindrical paper container 6 of FIG. (FIG. 6A) is a perspective view in a laid state. FIG. 6B is a perspective view of the upright state.

  FIG. 7 is an explanatory diagram showing an example of a paper container 6 with a stopper in which the stopper 5 is attached to the paper container 4 of FIG. A stopper 5 is attached to the hole F to form a stoppered paper container 6.

FIG. 8 is an explanatory view showing an example of a state in which the paper container with a stopper in FIG. 7 is sterilized with hydrogen peroxide. A heated mist of hydrogen peroxide 23 is sprayed from the mist irradiation port 24 onto the inner surface of the paper container 6 with a stopper. Thereafter, the hydrogen peroxide mist is heated and dried.

  FIG. 9 is an explanatory view showing an example in which the sterilized liquid food is aseptically filled in the paper container with a stopper of FIG. This is an example in which the sterilized liquid food 10 is aseptically filled in the sterilized paper container 6 with a stopper. A predetermined amount of liquid food 10 is filled from the filling nozzle 12 of the liquid food tank 11.

  FIG. 10 is an explanatory view showing an example of a liquid paper container (gable top type) created by the aseptic filling method of the present invention. After the liquid food 10 is aseptically filled, the top seal portion A is sealed, and a sealed liquid paper container 100 is formed. Although the gable top type liquid paper container 100 is shown as an example, the top seal portion A may be a flat top type.

  FIG. 11 is a cross-sectional view showing an example of the laminate of the present invention. It is sectional drawing which shows an example of the laminated body 30 which forms the blank of this invention. It comprises a laminate in which a polyethylene layer (outer surface) 31 / base material layer 32 / adhesive layer 34 / gas barrier layer 33 / adhesive layer 34 / polyethylene layer (inner surface) 35 are sequentially laminated. When using pattern printing or the like, the print layer G may be provided on the polyethylene layer 31 (outer surface).

  FIG. 12 is a cross-sectional view showing an example of a packaging bag. The packaging bag 7 includes at least a gas barrier base material layer 8 and a sealant layer 9. If it is necessary to improve the piercing property of the contents, a polyamide film may be used for the base layer or the intermediate layer.

  The form for implementing in more detail is demonstrated.

The laminated body 30 which comprises the blank 1 uses a paperboard as the base material layer 32, and a basic weight can usually use 200-500 g / m < ² > and a density 0.6-1.1 g / cm < ³ >. Paperboard such as milk base paper can be used. A 15 to 30 μm polyethylene film is bonded to the surface of the base material layer 32. The polyethylene film can be obtained by extrusion lamination with an extruder. A polyethylene layer (outer surface) 31 is formed.

  A gas barrier layer 33 is laminated on the back surface of the base material layer 32 through polyethylene as the adhesive layer 34. As the gas barrier layer 33, a polyethylene terephthalate film on which an inorganic oxide is deposited can be used. The adhesive layer 34 is bonded so that the vapor deposition surfaces of polyethylene and inorganic oxide face each other. Next, a polyethylene film as a polyethylene layer (inner surface) 35 is bonded to the polyethylene terephthalate film surface through polyethylene as an adhesive layer 34. A polyethylene film layer (inner surface) 35 having a thickness of 30 to 100 μm can be used. The polyethylene as the adhesive layer 34 and the polyethylene layer (inner surface) 35 can also be formed into a film by an extruder.

  As the polyethylene used for the adhesive layer 34, high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE) can be used. In addition, polyolefin resins such as ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl methacrylate copolymer (EAA), ionomer, and polypropylene (PP) can also be used. These resins are formed into a film with an extruder and bonded.

  The polyethylene layer (inner surface) 35 can be HDPE, LDPE, MDPE, or LLDPE, and may be a single layer or multiple layers. LLDPE is preferred. In order to reduce off-flavors, it is necessary to select an antioxidant. If possible, a film containing no phenolic antioxidant is preferred.

  As the gas barrier layer 33, a polyethylene terephthalate film or a polyamide film bonded with an aluminum foil, or a vapor deposited inorganic oxide can be used. As the inorganic oxide, aluminum oxide, silicon oxide, magnesium oxide, or the like can be used. It is also possible to use a film of ethylene vinyl alcohol copolymer as a gas barrier layer. In this case, it is necessary to confirm barrier properties and other physical properties in advance.

  As a structure of the laminated body 30, for example, polyethylene layer (outer surface) / base material layer / adhesive layer / aluminum foil / polyethylene terephthalate film / adhesive layer / polyethylene layer (inner surface), polyethylene layer (outer surface) / base material layer / adhesive layer / Silicon oxide deposition / polyethylene terephthalate film / adhesion layer / polyethylene layer (inner surface), polyethylene layer (outer surface) / base material layer / adhesion layer / magnesium oxide deposition / polyethylene terephthalate film / adhesion layer / polyethylene layer (inner surface), etc. Can be mentioned.

  This laminated body 30 is made into a roll shape or a sheet shape. Then, according to the shape of the container, a fold line, outline cutting, etc. are processed by a general known method to form a blank 1.

  Next, the front surface of the back seal 110 of the blank 1 and the back surface of the back panel 150 are heat-sealed to create a folded sleeve 2, and a plurality of them are packed together and packed in the packaging bag 7. At this time, in order to set the oxygen concentration in the packaging bag to 5% or less, either vacuum suction or nitrogen substitution, or vacuum suction and nitrogen substitution is performed. The package bag with the oxygen concentration adjusted and sealed may be stored until it is sterilized by electron beam. Since the packaging bag 7 is formed of at least the gas barrier base material layer 8 and the sealant layer 9, the packaging bag 7 blocks oxygen in the atmosphere. Therefore, it is possible to prevent the oxygen concentration from exceeding 5% until the electron beam is sterilized.

  Next, the sleeve folded by electron beam irradiation from the outside of the packaging bag is sterilized by electron beam. Sterilize in a state where the oxygen concentration in the packaging bag is kept below 5%. The packaging bag also needs to have electron beam resistance. If possible, it is preferable to select a material so that no odor is generated from the sealant layer of the packaging bag, that is, the polyethylene film. If possible, a polyethylene film containing no phenolic antioxidant is preferred.

  Open the packaging bag, supply the sterilized and folded sleeve 2 to an aseptic filling and packaging machine in an aseptic environment, heat seal the bottom part, mold and close it, attach the plug 3 and with the plug After the paper container 6 was formed and sterilized with the hydrogen peroxide 23, the sterilized liquid food 10 was aseptically filled, the top seal portion A was heat sealed, and aseptically filled A liquid paper container 100 is formed. By forming it into a gable roof mold, a Gobeltop paper container can be made. If it is molded into a flat top type, a flat top type paper container is formed.

  Patterns and characters can be expressed on the surface of the polyethylene layer (outer surface) 31 of the laminate. As a printing method, a normal method such as gravure printing, offset printing, inkjet printing, flexographic printing, or the like can be used. The surface layer may be subjected to corona treatment or the like to improve adhesion with the printing ink.

  Hereinafter, specific examples of the present invention will be described.

Polyethylene was extruded by 20 μm and laminated on the surface of a paperboard having a basis weight of 350 g / m ² .

Next, a polyethylene terephthalate film having a gas barrier layer deposited with a thickness of 30 nm and a polyethylene terephthalate film having a thickness of 12 μm and a linear low-density polyethylene having a thickness of 60 μm were bonded together by sand-polyethylene at 20 μm. The linear low density polyethylene 60 μm used was prepared in advance by an extrusion method.

  Next, the back surface of the paperboard and the silicon oxide vapor deposition surface of the intermediate layer were sand-polished with EMMA 30 μm and bonded together.

  Next, the created laminate was subjected to ruled lines and blanking to create a blank for forming a 1L, 70-corner (longitudinal broken line interval) gable top type paper container.

  The front surface of the blank back seal and the back surface of the back panel were heat-sealed to form a folded sleeve, and a plurality of the sleeves were collectively sealed in a packaging bag. The packaging at this time was hermetically packaged with an oxygen concentration of 5% by replacing the air in the packaging bag with nitrogen. A packaging bag having a structure in which an aluminum oxide-deposited polyamide film of 12 μm and a low-density polyethylene of 40 μm as a sealant layer were bonded as a gas barrier base material layer was used. The packaging bag was packed in a cardboard case and irradiated with an electron beam dose of 15 kGy to sterilize the sleeve.

  The sterilized sleeve was opened and supplied to an aseptic filling and packaging machine in an aseptic environment, and a rectangular cylindrical sleeve, a paper container formed with a bottom part, and a paper container with a stopper fitted with a mouth part were sequentially formed.

  Next, 35% hydrogen peroxide was vaporized by heating, a mist was prepared and sprayed on the inner surface of a paper container with a stopper, and then dried.

  A certain amount of sterilized distilled water was aseptically filled into the stoppered paper container, and a liquid paper container sealed with a top seal was prepared.

  A liquid paper container was prepared in the same manner as in Example 1 except that the air in the packaging bag was vacuumed instead of replaced with nitrogen and sterilized with gamma rays instead of sterilizing with electron beams. The gamma ray dose was also set at 15 kGy.

  A liquid paper container was prepared in the same manner as in Example 1 except that the air in the packaging bag was vacuumed and replaced with nitrogen.

<Comparative Example 1>
A liquid paper container was prepared in the same manner as in Example 1 except that the air in the packaging bag was not replaced with nitrogen.

<Comparative example 2>
A liquid paper container was prepared in the same manner as in Example 1 except that the air in the packaging bag was replaced with nitrogen so that the oxygen concentration was 10%.

  The liquid paper containers prepared in Examples and Comparative Examples were stored at room temperature for 3 months. At the same time, the glass bottle was filled with the same distilled water and stored at room temperature for 3 months. Sensory evaluation was performed by the three-point identification method for the smell of distilled water in a glass bottle. 10 panelists, ○: no significant difference, ×: significant difference.

実施例では、包装袋内の酸素濃度を５％以下にすることにより、異臭について有意差が認められなかった。比較例では、有意差が認められた。ポリエチレン（内面）の酸化劣化が低減したためである。実施例、比較例ともに無菌保証レベルは、１０^−６ＳＡＬで良好
であった。

In the examples, when the oxygen concentration in the packaging bag was set to 5% or less, no significant difference was observed with respect to off-flavors. In the comparative example, a significant difference was observed. This is because the oxidative deterioration of polyethylene (inner surface) has been reduced. The sterility assurance level was good at 10 ⁻⁶ SAL in both Examples and Comparative Examples.

DESCRIPTION OF SYMBOLS 1 Blank 2 Sleeve 3 Square cylindrical paper container 4 Paper container 5 Port stopper 6 Paper container with stopper 7 Packaging bag 8 Gas barrier base material layer 9 Sealant layer 10 Liquid food 11 Liquid food tank 12 Filling nozzle 20 Electron beam
21 Sterilization room 22 Electron beam irradiation port
23 Hydrogen peroxide 24 Mist irradiation port 30 Laminate
31 Polyethylene layer (outer surface)
32 Base material layer 33 Gas barrier layer 34 Adhesive layer 35 Polyethylene layer (inner surface)
100 Liquid paper container (gable top type)
110 Back seal 120 Left panel 130 Front panel 140 Right panel 150 Back panel 200 Liquid paper container manufacturing flow 210 Dotted frame A Top seal part B Top part C Side wall part D Bottom part E Ruled line F Hole G Print part

Claims (6)

A laminate in which paperboard is used as a base material layer, and at least a polyethylene layer (outer surface) / base material layer / gas barrier layer / polyethylene layer (inner surface) are sequentially laminated.
Forming a blank,
A back seal is bonded from the blank to form a folded sleeve;
Raise the sleeve, form a square cylindrical sleeve, mold the bottom of the square cylindrical sleeve to form a paper container,
A stopper is attached to the paper container to form a stoppered paper container, the inner surface of the stoppered paper container is sterilized with hydrogen peroxide, and the sterilized liquid food is sterilized in the stoppered paper container. Filling,
A method for sterilizing a sealed liquid paper container,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of the air in the packaging bags is adjusted to 5% or less,
A liquid paper container sterilization method, wherein radiation is applied from the outside of the packaging bag, and the sleeve is sterilized by radiation.   2. The liquid paper container sterilization method according to claim 1, wherein the radiation sterilization is electron beam sterilization using an electron beam.   3. The method for sterilizing a liquid paper container according to claim 1, wherein the inside of the packaging bag is vacuum suction, nitrogen replacement, or vacuum suction and nitrogen replacement.   The packaging bag is composed of at least a gas barrier substrate layer and a sealant layer, and the gas barrier substrate layer is a polyethylene terephthalate film on which any one of aluminum, aluminum oxide, silicon oxide, and magnesium oxide is deposited. The liquid paper container sterilization method according to any one of 1 to 3.   A liquid paper container formed by the sterilization method according to claim 1. A laminate in which paperboard is used as a base material layer, and at least a polyethylene layer (outer surface) / base material layer / gas barrier layer / polyethylene layer (inner surface) are sequentially laminated.
Means for forming a blank;
Means for bonding a back seal from the blank to form a folded sleeve;
Means for raising the sleeve and forming a rectangular cylindrical sleeve; and means for forming a paper container by molding the bottom of the rectangular cylindrical sleeve;
Means for forming a paper container with a stopper by attaching a stopper to the paper container; means for sterilizing the inner surface of the paper container with a stopper with hydrogen peroxide;
Means for aseptically filling the sterilized liquid food into the stoppered paper container;
A sealed liquid paper container sterilization device comprising:
After the means for forming the sleeve,
The sleeve is sealed in a plurality of packaging bags, the oxygen concentration of the air in the packaging bags is adjusted to 5% or less,
An apparatus for sterilizing a liquid paper container, comprising means for radiating radiation from the outside of the packaging bag and radiating the sleeve with radiation.

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