METHOD OF SUBSTITUTING INERT GAS AND APPARATUS THEREFORE

Abstract: This invention relates to a method of substituting an inert gas by blowing out an inert gas into a vessel while the opening of the vessel is covered with an inert gas substitution unit (5,20) having inert gas outlet (7,30) so as to substitute the inert gas in the vessel, and covering the opening of the vessel with a lid film (15) after substitution. The invention dis­ closes also an inert gas substitution unit (5) having a flat plate on which the inert gas outlet (7) is formed. Disclosed also is an inert gas substitution unit (20) having a chamber (21) whose bottom surface is open and blowing an inert gas into the vessel while covering the opening of the vessel with the chamber (21).

Description: The present invention relates to an apparatus which substitutes an inert gas for air in a head space of a container filled with contents such as food. US-A-3,039,882 describes a process for packaging powdered soluble coffee by means of a pressure differential generated by an inert gas which displaces the oxygen that may be associated with the coffee powder while US-A-4,312,171 discloses a method and apparatus for purging air from a product filled container when one end of the container is open. The apparatus disclosed in US-A-4,312,171 includes a plate type flow control valve having an apertured planar flow control surface which overlaps the opening of the container and is spaced a short distance therefrom. A neutral air purging gas, preferably saturated steam, is continuously directed at low pressure and relatively high volume through the aperture into the open end of the container thereby creating a gentle non-turbulent flow of air out of the container along an unobstructed flow path defined by the periphery of the open end of the container and the planar flow control surface. Recently, in food packaging, a gas-substitution process has been carried out which substitutes an inert gas for air surrounding food within a container before sealing in order to prevent food from being denatured or deteriorated due to oxygen. Inert gases used for the above-described gas-substitution packaging are normally nitrogen or carbonic gas, and rarely a mixture of both the gases. This is effective in suppression of aerobic bacteria of the packaged food, retention of effective components, rancidity prevention, discoloration prevention, mold prevention and the like. A conventional gas-substitution process has been carried out by inserting a filled container into a chamber capable of being closed, making the interior of the chamber vacuous to remove air from the filled container, thereafter blowing an inert gas into the chamber to fill a head space of the container with the inert gas, and sealing an opening of the container within the chamber. In the above-described gas-substitution process the inert gas is blown into the chamber after a vacuum has been formed, and therefore, it takes time, with the result that work efficiency is poor. Furthermore, since the inert gases are blown into the chamber every time, a large quantity of inert gases are required, resulting in a great loss of inert gases. Moreover, when the aforesaid conventional method is applied to a lateral type filling and sealing machine for a container which automatically carries out the step of filling a container with a content and sealing a cover, it is necessary to open and close the chamber as the conveyor conveying the container moves, and to position a conveyor portion on which the container is placed within the chamber whilst still being able to evacuate the chamber. Thus, there arises the further drawback that the apparatus becomes complicated and expensive. Alternatively, a method has been carried out which comprises the steps of directly blowing an inert gas against an opening of a container being conveyed by a conveyor without producing a vacuum and deaeration, and substituting the inert gas for air within the head space. This method of directly blowing the inert gas without first producing a vacuum poses problems in that not only do the inert gases escape into the atmosphere but also it is difficult to enhance the gas-substitution rate. It is an object of this invention to provide a relatively simple and inexpensive apparatus for substituting an inert gas for a gas in the head space of a container which involves less loss of the supplied inert gases, a short substitution time and a high substitution rate, and which can be easily applied to a horizontal type filling and sealing machine which transports a non-sealed filled container by means of a conveyor and seals an opening thereof with a cover material film. To this end, according to the present invention there is provided an inert gas substitution apparatus for non- sealed, open-topped containers filled with a content, the apparatus including a conveyor for moving a filled container to a gas substitution station and, after a predetermined period, for moving the container from said gas substitution station to a sealing device immediately adjacent thereto, the gas substitution station comprising a plate having a flat bottom surface of sufficient size to cover the open top of said container, an inert gas blow opening formed in said plate in such a way as to be capable of being positioned centrally relative to the open top of said container, and an inert gas supply pipe connected to said inert gas blow opening for continuously supplying inert gas to said opening, characterised in that there are further formed in said plate a plurality of air escaping holes spaced from said inert gas blow opening in such a way as to be capable of being positioned relative to the open top of said container adjacent an inner peripheral wall thereof, and in that said plate is disposed relative to said container in such a way that the flat bottom surface thereof abuts the open top of the container and allows the open top to slide smoothly across the flat bottom surface when the container moves from the gas substitution station to the sealing device, said plate having a leading edge portion that directs the open top of the container into said abutting relationship on movement of the container to the gas substitution station. Further, according to the invention there is provided an inert gas substitution apparatus for non-sealed, open-topped containers filled with a content, the apparatus including a closure of sufficient size to cover the open top of a container, an inert gas blow opening formed in said closure, and an inert gas supply pipe connected to said inert gas blow opening, characterised in that said closure comprises an open-bottomed chamber formed by side walls and a top wall, said inert gas blow opening is formed in one of said side walls, and an air exhaust opening is provided in a side wall opposite said inert gas blow opening so as to establish a guided flow of gas within said chamber and the head space of the open-topped container above the content thereof. The invention also provides an inert gas substitution apparatus for non-sealed, open topped containers filled with a content, the apparatus including a closure of sufficient size to cover the open top of a container, an inert gas blow opening formed in said closure, and an inert gas supply connected to said inert gas blow opening, characterised in that said closure comprises an open bottomed chamber formed by side walls and a top wall, said inert gas blow opening is formed in one of said side walls, an air exhaust opening is provided in a side wall displaced from said inert gas blow opening, and a gas flow deflecting plate is suspended from said top wall so as to establish a guided flow of gas from said gas blow opening to said air exhaust opening within said chamber and the head space of the open topped container above the content thereof. In accordance with the invention, the opening of a non-sealed filled container transported by the conveyor is covered with the inert gas substitution apparatus, and in this state the inert gas is directly blown into the container. Therefore, the inert gas can be substituted for the gas within the container in a short period of time and with a high substitution rate without sealing the whole container in a chamber. The loss of inert gases is small. Furthermore, the opening of the container is covered with the cover material film immediately after the substitution of the inert gas, and therefore, it is possible to cutoff the contact of the substitute gas within the container from the external atmosphere. Embodiments of an inert gas substitution apparatus in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side conceptual view of one embodiment of the invention applied to a lateral type filling and sealing machine for a molded container; Figure 2 is a fragmentary side sectional view of the inert gas substitution apparatus used in Figure 1; Figure 3 is a plan view of the inert gas substitution apparatus of Figure 2; Figure 4 is a side sectional view of another embodiment of an inert gas substitution apparatus according to the present invention applied to a lateral type filling and sealing machine for a molded container; FIG. 5 is a plan view of apparatus shown in FIG. 4; FIG. 6 is a side sectional view of apparatus shown in FIG. 4; FIG. 7 is a side sectional view of another embodiment of an inert gas substitution apparatus; FIG. 8 is a plan sectional view of another embodiment of an inert gas substitution apparatus; and FIG. 9 is a plan sectional view of another embodiment of an inert gas substitution apparatus. BEST MODE FOR EMBODYING THE INVENTION Preferable embodiments of an inert gas substitution apparatus according to the present invention are shown in FIGS. 1 to 9. An inert gas substitution apparatus according to the present embodiment is installed between a filling device and a sealing device in a known filling and sealing machine for filling a molded container with a content and sealing a cover. A molded container 1 is formed from a plastic, a laminated film of a metal foil and a plastic film or paper, and has a gas barrier property. The molded container 1 is filled with a content by a filling device not shown and conveyed below the gas substitution apparatus, which will be described hereinbelow, under the state wherein the container 1 is fitted and supported on a carriage 3 of a carriage conveyor 2. A gas substitution apparatus 5 shown in FIGS. 1 to 3 is composed of a plate comprising a plastic flat plate 6 whose lower surface is smooth and having an approximately rectangular shape, and an inner gas supply pipe 11 having one end connected to an inner gas blow opening 7 bored in said flat plate 6 while the other end connected to a source of supplying an inert gas. The flat plate 6 has the size enough to cover the opening of the container, and in the peripheral portion of the inert gas blow opening 7 are bored a plurality of air escape holes 8 within the range of the open area of the container. The first plate 6 has its rear end edge, which is on the entering side of the molded container 1 conveyed by the conveyor, corner-cut 9 in the form of an arc so that the molded container 1 conveyed by the conveyor may be smoothly moved into and below the first plate. The foremost upper edge portion on the outlet side (that is, at the downstream) of the molded container is inclined through the approximately same angle as the supply angle of a cover material film 15 so that the foremost end edge 10 thereof may be located in proximity of a film keep roll 17. Reference numeral 11 designates an inert gas supply pipe connected to the inert gas blow opening 7 through a suitable connector 12, the other end thereof being connected to a source of supplying inert gases not shown. The inert gas substitution apparatus 5 constructed as described above is secured upwardly of a conveyor 2 by a suitable mounting means at a level in close contact with an opening of the molded container 1 passing through the lower portion of the apparatus 5 and with the foremost end edge 10 placed in proximity of the keep roll 17. Reference numeral 18 designates a sealer for heat-sealing the cover material film 15 on the opening of the container. The cover material film 15 is wound back from a supply roll 16 and guided so as to cover the opening of the container by the keep roll 17. A preferred mode of embodiment of a method according to the present invention embodied by the above-described apparatus will be described hereinafter. The molded container 1 filled with the content by a filling device not shown is intermittently conveyed while being fitted in and supported on the carrier 3 of the carrier conveyor 2, enters below the plastic flat plate 6 of the inert gas substitution apparatus and stops for a predetermined period of time when the center of the opening thereof reaches the lower portion of the gas blow opening 7. Then, the inert gases which are continuously blown from the gas blow opening 7 of the flat plate 6 are blown into the head space within the open container 1. As the result, air having been present within the head space of the open container 1 is discharged out of the air escape holes into outside and substituted for the inert gases. After a predetermined period of time, the conveyor is again driven so that the molded container 1 with the inert gas substitution terminated moves while the open flanged portion thereof slidably contacting the bottom surface of the flat plate, and when the container 1 moves beyond the front end edge 10 of the flat plate 1, the container again moves while the opening thereof is covered with the cover film 15 at an extremely slight interval. Accordingly, the opening of the container 12 moved away from the foremost end of the flat plate 6 is immediately covered with the cover film 15, and therefore, the substituted gases are less escaped outside. Thereafter, the sealer 18 is actuated in a known manner to cause the cover film 16 to be heat-sealed to the flanged portion of the container 1, and after sealing, the cover portion is trimmed from the cover film, thus completing sealing of the cover. The apparatus used in the above-described embodiment was used to carry out the inert gas substitution under the following conditions. Processing ability of line: 20 shot/min. Container: A 80 cc round type cup, into which 65 cc of water is put, a head space being 15 cc. Cover material: Aluminum packing material Inert gas: Nitrogen was continuously blown at 5 lit./min. As the result, the nitrogen was able to be substituted for air within the head space with the substitution rate of more or less 90 per cent. FIGS. 4 to 9 show another preferred embodiments of an inert gas substitution apparatus according to the present invention. In the present embodiment, an inert gas substitution apparatus 20 is composed of a chamber 21, an inert gas supply path 22, an air exhaust path 23 and an opening covering member 28 of a molded container. The chamber 21 has a bottom opened, and a top and a peripheral side surrounded by a top wall 24 and a side wall 25, respectively, the chamber 21 having its shape in the form of a cylinder or tube adjusted to the shape of an opening of a molded container for gas substitution. As shown in FIG. 4, a lower end 27 of the side wall 25 is to be positioned at the flanged portion of the molded container fitted in supported on the carriage 26. Accordingly, when the molded container 1 is positioned at the lower part of the chamber 21, the opening of the molded container 1 assumes a state where the opening is covered with the chamber 21. If the shape of the opening of the molded container is a square, the shape of the chamber is formed so that a section thereof is a square. At an upstream of a conveyor of the side wall 25 of the chamber 21 is provided an inert gas blow opening 30, and at a downstream thereof is provided an air exhaust opening 31, and with the blow opening 30 and the exhaust opening 31 are communicated an inert gas supply path 22 and an air exhaust path 23, respectively. A pipe from an inert gas cylinder not shown is connected to the other end of the inert gas supply path 22. A vacuum pump not shown is connected to the other end of the air exhaust path 23. At a downstream of the conveyor at the lower end of the side wall of the chamber 21 is provided a cover member 28 so as to cover the opening of the molded container 1 till the molded container 1 moves from the lower portion of the chamber 21 and the opening thereof is covered with the cover material film 15. Accordingly, the cover member 28 extends to a position in proximity to a keep roller 29 of the cover material film. In the illustrated embodiment, two chambers are provided in parallel with each other so that gas substitution may be simultaneously carried out for two molded containers, said two chambers, inert gas supply path 22, air exhaust path 23 and cover member 28 being manufactured from plastics. The chamber 21 has its top wall 24 depressed as shown in FIG. 6 so that a flow of the inert gases blown out of the inert gas blow opening 30 may be deflected into the container 1. Thereby, the inert gases may be evenly blown into the head space of the molded container and the air may be efficiently discharged out of the air exhaust opening. In addition, the volume of the chamber 21 is decreased, and the gas substitution may be effectively carried out with a small quantity of inert gases. It is noted that as means for deflecting a flow of inert gases into the container, a gas flow deflecting plate 32 may be provided which is suspended obliquely toward the gas flow from the top wall as shown in FIG. 7. The inert gas substitution apparatus 20 constructed as described above is secured upwardly of the conveyor by a suitable mounting means at a level in proximity to the opening of the molded container 1 passing the lower portion of the apparatus 20 and with the foremost end edge of the covering member 28 placed in proximity to the keep roll 29. It is to be noted that the gas substitution apparatus 20 may be designed so that the apparatus 20 is moved up and down in synchronism with the movement of the conveyor. Reference numeral 19 designates a drawing chain for the carrier conveyor 2. FIGS. 8 and 9 show another embodiment in which a gas flowpassage within the chamber 21 is modified. In the FIG. 8 embodiment, a diffusion plate 35 provided with a striped vent hole 36 in the vicinity of an inert gas blow opening 30 is provided suspended from the top wall. Thereby, the inert gases blown out of the gas blow opening 30 are evenly blown in a diffusion flow into the head space. In the FIG. 9 embodiment, a gas flow deflecting plate 38 curved from the gas blow opening to a portion in the vicinity of a central portion of a can opening is suspended from the top wall. According to the present embodiment, the inert gases blown out of the gas blow opening 30 make a round travel while flowing along the peripheral walls of the chamber and molded container, and therefore, air within the head space can be positively discharged, thus being effective in enhancing the substitution rate. While in the above-described embodiment, the air exhaust path 23 is provided in communication with the air exhaust opening 31, it is to be noted that if a design is made so that air within the head space is directly discharged by the inert gases without using an exhaust device such as a vacuum pump, the aforesaid air exhaust path need not be provided. While in the above-described embodiment, the inert gases are supplied while discharging air within the chamber and molded container by means of a vacuum pump, it is to be noted that air within the head space may be directly discharged by the inert gases blown into the container without using using the exhaust device such as a vacuum pump. In that case, the end of the air exhaust path is opened to atmosphere. In the case where the contents are granular material, if the inert gases are supplied after air within the chamber and container has been sufficiently drawn by a vacuum pump, the gas substitution can be positively carried out. Furthermore, while in the above-described embodiment, nitrogen is used as the inert gases, it is to be noted that if heated nitrogen is used, the cover of the container is inwardly stretched at normal temperatures to improve the external appearance of a package. This is particularly effective in case of a cold package. INDUSTRIAL AVAILABILITY This invention can be utilized for a gas substitution packaging in which in filling a plastic molded cntainer with a content and sealing an opening with a cover material film, sealing and packaging are effected after substitution of an inert gas such as nitrogen for a gas such as air within the container in order to prevent oxidization of the content.

Claims: An inert gas substitution apparatus for non-sealed, open-topped containers filled with a content, the apparatus including a conveyor (2) for moving a filled container (1) to a gas substitution station (5) and, after a predetermined period, for moving the container (1) from said gas substitution station (5) to a sealing device (18) immediately adjacent thereto, the gas substitution station (5) comprising a plate (6) having a flat bottom surface of sufficient size to cover the open top of said container (1), an inert gas blow opening (7) formed in said plate (6) in such a way as to be capable of being positioned centrally relative to the open top of said container (1), and an inert gas supply pipe (11) connected to said inert gas blow opening (7) for continuously supplying inert gas to said opening, characterised in that there are further formed in said plate (6) a plurality of air escaping holes (8) spaced from said inert gas blow opening (7) in such a way as to be capable of being positioned relative to the open top of said container (1) adjacent an inner peripheral wall thereof, and in that said plate (6) is disposed relative to said container (1) in such a way that the flat bottom surface thereof abuts the open top of the container (1) and allows the open top to slide smoothly across the flat bottom surface when the container (1) moves from the gas substitution station (5) to the sealing device (18), said plate (6) having a leading edge portion (9) that directs the open top of the container (1) into said abutting relationship on movement of the container (1) to the gas substitution station (5). An inert gas substitution apparatus for non-sealed, open-topped containers filled with a content, the apparatus including a closure (21) of sufficient size to cover the open top of a container (1), an inert gas blow opening (30) formed in said closure (21), and an inert gas supply pipe connected to said inert gas blow opening (30), characterised in that said closure (21) comprises an open-bottomed chamber formed by side walls (25) and a top wall (24), said inert gas blow opening (30) is formed in one of said side walls (25), and an air exhaust opening (31) is provided in a side wall (25) opposite said inert gas blow opening so as to establish a guided flow of gas within said chamber and the head-space of the open-topped container (1) above the content thereof. An inert gas substitution apparatus in accordance with claim 2 wherein a covering member (28) in the form of a flat plate is provided at a bottom edge of a side wall (25) of the chamber and extends outwardly therefrom. An inert gas substitution apparatus in accordance with claim 2 or claim 3 wherein means (24,32 or 35) are provided on said top wall (24) for deflecting the flow of gas within said chamber and open-topped container (1). An inert gas substitution apparatus for non-sealed, open topped containers filled with a content, the apparatus including a closure (21) of sufficient size to cover the open top of a container (1), an inert gas blow opening (30) formed in said closure (21), and an inert gas supply connected to said inert gas blow opening (30), characterised in that said closure (21) comprises an open bottomed chamber formed by side walls (25) and a top wall (24), said inert gas blow opening (30) is formed in one of said side walls (25), an air exhaust opening (31) is provided in a side wall (25) displaced from said inert gas blow opening (30), and a gas flow deflecting plate (38) is suspended from said top wall (24) so as to establish a guided flow of gas from said gas blow opening (30) to said air exhaust opening (31) within said chamber and the head space of the open topped container (1) above the content thereof. An inert gas substitution apparatus in accordance with any of claims 2 to 5 wherein the air exhaust opening (31) is connected to a vacuum pump.

Inventors: AKITOSHI, HIROSHI, IKEDA, MASAOMI, NAGATANI, NOBUAKI, TERAJIMA, YOSHIMI
Applicants: TOYO SEIKAN KAISHA, LTD.
Application year: 1987
Main classification: B65B31
IPC codes: B65B31