JPS6139202B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing vacuum canning made of flexible containers, and more specifically, even when a thin flexible material is used for the container body, the pressure generated by hot filling is The present invention relates to a manufacturing method for canning baquiyum that can alleviate the difference without impairing the aesthetic appearance of the container. (Technical Background of the Invention) In general, when a can or other container made of flexible material is filled with contents at high temperature, the internal pressure decreases as the temperature drops, the internal volume decreases, and the pressure decreases due to condensation of steam. This causes the problem that the container itself deforms irregularly due to external pressure. Such a reduction in the internal pressure of the container depends on the full filling volume of the container, the type of content (temperature dependence of content density, etc.), the filling amount, the filling temperature, and the final temperature of the container. Table 1 shows the degree of vacuum inside the container and the filling (hot pack) temperature when a container with a full filling volume of 263 c.c. is filled with 250 g of water at various temperatures and then immediately sealed and cooled to room temperature (20°C). This shows the relationship between The measurements were carried out using a metal can and metal lid that were virtually undeformed up to a vacuum level of 60 cmHg. Table 1 Hot Pack Temperature (℃) Degree of Vacuum (cmHg) 50 19.5 60 27.0 70 35.5 80 44.3 85 48.5 90 53.0 95 57.0 *Room Temperature 20℃ In the case of cans, the thickness of the constituent material should be increased in response to this reduced pressure. Alternatively, the deformation is prevented by increasing the rigidity of the can by forming lateral beads, but in the case of flexible containers, it is difficult to avoid this deformation. For example, Table 2 shows the experimental values obtained for the degree of vacuum at which buckling begins for a cylindrical body made of polypropylene with a modulus of elasticity of 110 Kg/mm ² (at 25° C.), as a function of the height, diameter and thickness of the cylinder. In other words, as is clear from Table 2, the flexible body (in Table 2, the thickness
It can be seen that buckling of a 0.5 mm cylinder begins at an extremely low vacuum of 8 cmHg or less.

[Table] (Prior art) Conventionally, in order to prevent irregular deformation due to external pressure,
Even for flexible containers, without compromising the beauty of the container,
Various means for producing a predetermined deformation have been proposed, and these methods can be broadly divided into using a lid that can be deformed inwardly, hot filling the contents,
After sealing, the lid is deformed inward by an amount commensurate with the reduced volume of the contents, and a fold pattern that causes a reduction in the internal volume of the container is formed in advance on the container wall surface, or a crease pattern is formed across the container body. There is a method of absorbing reduced pressure by making the surface shape polygonal rather than circular, and deforming the container wall surface by an amount commensurate with the reduction in contents after filling and sealing. One type of the former category is one in which the bottom plate of a paper container is recessed in the shape of a needle, and the internal negative pressure is brought to zero by recessing it into a dome shape.
(Japanese Utility Model Publication No. 164112, Japanese Utility Model Application Publication No. 164112, Japanese Utility Model Application Publication No. 16205)), a bottom plate member molded to form a rim of a predetermined shape is used, and after filling and sealing, a pressing die is used to push the bottom plate member toward the opening of the container. A device that absorbs negative pressure by deforming it into
JP-A-55-48061, JP-A-54-154695, in which the lid body is provided with a convex portion that bulges outward, and the convex portion is deformed inward after filling and sealing. ), etc., and as belonging to the latter, Japanese Patent Application Laid-Open No. 13369/1983 describes that a part of the side surface of the container is preliminarily formed inward in response to a decrease in the internal pressure of the container. A device is described in which folds are provided in a predetermined pattern to form a recess in a predetermined constant shape. (Problems with the Prior Art) However, with the above-described means of relieving internal negative pressure by deforming the lid, the rigidity is such that the container body is prevented from deforming until the lid deforms. Although this problem may not occur with some cans, if the container body is made of a flexible material, deformation of the body will necessarily occur prior to deformation of the lid. Even if this deformation of the body is restored to its original state by deformation of the lid, there is a problem in that creases remain in the deformed portion of the body even after restoration. The occurrence of these creases causes cracks and pinholes in the gas barrier layer such as metal foil on the body of the container, resulting in a decrease in gas barrier properties and storage stability of the contents, as well as impairing the aesthetic appearance of the container. It turns out. In addition, to explain the occurrence of folds and wrinkles, during the cooling process after hot filling and sealing, the body wall becomes depressed and deformed as the internal pressure is reduced, but in conventional flexible containers, the body wall bends and deforms. Even if such local deformation occurs and the deformed portion returns to its original state, creases will remain in the deformed portion. (Technical Problem of the Invention) Therefore, an object of the present invention is to prevent irregular deformation of the container body even though the container body is formed from a relatively thin flexible material, and to prevent the container body from being irregularly deformed. To provide a method for manufacturing canned baquium made of a flexible material that eliminates the occurrence of creases in the parts. Another object of the present invention is to prevent the occurrence of creases in the container body in a method for manufacturing canned baquium in which the concave deformation in the container body is recovered by the concave deformation of the lid after hot filling and sealing of the contents. prevent,
To provide a method for producing canned baquiyum, thereby ensuring excellent appearance and preservation of contents. (Technical Means of the Invention) The present invention provides a method for manufacturing a canned baquium to achieve the above object, and provides a method for manufacturing a canned baquium using a body and a lid made of a flexible material. ; The body has a metal foil with a thickness of 9 to 50 μm, and the overall thickness is 200 to 500 μm.
Use a cylindrical molded product of a flexible laminated sheet containing metal foil that has an elastic modulus of 100 to 400 Kg/mm ² and can be bent and deformed without creating creases; As the lid, a metal foil with a thickness of 50 to 120 μm is used. A ring-shaped U-shaped groove around which the open edge of the body is inserted to seal the two, and a dome-shaped groove extending outward in the center thereof. bulge, the ratio of bulge height/diameter is 0.05 to 0.2
hot filling the container consisting of the body and the lid with the contents and sealing the container; The present invention relates to a method for producing a vacuum canned product made of a flexible container, which is characterized by cooling; and pressing the central portion of the lid of the canned container after cooling inward to forcibly jump and deform the central portion of the lid. (Effects of the Invention) The present invention provides that the body of a canned baquium is formed of a flexible laminated sheet containing metal foil having a certain thickness and characteristics, while the lid is formed of a metal foil of a certain thickness and When using a lid made of a metal foil-containing coating sheet having a certain shape, it is possible to limit the deformation that occurs in the body during cooling of the hot-filled can to the above-mentioned bending deformation without generating creases; This is based on the knowledge that by deforming the lid in a flying manner after cooling, it is possible to restore the deformation of the body to its original state without causing creases. First, according to the present invention, the metal foil has a thickness of 9 to 50 μm, and the total thickness is 200 to 500 μm.
By forming the cylindrical body with a flexible laminated sheet containing metal foil having an elastic modulus of 100 to 400 Kg/ ^mm2 , the bending that causes creases during cooling of hot-filled canned cans can be avoided. Transformation (See Figure 8-A)
This makes it possible to limit the deformation due to internal depressurization to a bending deformation (Fig. 8-B). Therefore, by limiting the concave deformation caused by the internal vacuum to a bending deformation rather than a bending deformation, it is possible to prevent creases from remaining after the container body recovers from its deformation. The deformation of the vessel wall due to internal decompression results in bending deformation, but whether or not it results in bending deformation depends on the type, thickness, and bending rigidity of the material constituting the cylindrical body. In this sense, incorporating metal foil into the flexible sheet constituting the body is extremely effective in preventing bending deformation, and from this perspective, the thickness of the metal foil should be 9 to 50 μm. If the thickness of the metal foil is smaller than the above range, the rigidity will be insufficient, and if it is larger than the above range, deformation will occur rapidly and locally, causing folds and wrinkles. , does not function as a flexible container. For the same reason, the overall thickness of the laminated sheet is
200 to 500μm, elastic modulus 100Kg/mm ² to 400
By setting it within the range of Kg/mm ² , it is possible to effectively eliminate the occurrence of creases during deformation. In the present invention, after hot filling and sealing, the lid jumps inward and deforms to return the container body from the deformed state to its original state. At this time, the metal foil constituting the container lid is By setting the thickness in the range of 120 μm to 120 μm, jump deformation can be easily performed. Note that the jump deformation refers to deformation that suddenly jumps from a certain position on the wall surface to another certain position when the load exceeds a certain limit value. If this thickness is smaller than the above range, normal concave deformation other than jump deformation is likely to occur, while if the thickness exceeds the above range, the deformation itself becomes difficult.
In addition, this lid has a bulge in the center, but by setting the bulge height/diameter ratio in the range of 0.05 to 0.2, it can easily be deformed without deteriorating the appearance characteristics of the lid. can be made to do so. That is, if this ratio is larger than the above range, the jump deformation itself becomes difficult, or even if jump deformation is performed, wrinkles tend to occur in the peripheral area, whereas if this ratio is smaller than the above range, the jump deformation itself tends to be difficult. The degree of reduction in internal volume due to transfer deformation becomes small, making it unsuitable for the purpose of the present invention. As detailed above, according to the present invention, all of the above-mentioned requirements are combined, and the container body and lid are free from irregular deformation, have an excellent appearance, and have an excellent content preservation property. This method enables the production of canned baquium made from flexible materials. (Description of Preferred Embodiments of the Invention) Container Structure The container used in the present invention is formed from a body 1 shown in FIGS. 1 to 3 and a lid 2 shown in FIGS. 4 to 6. As will be described in detail later, the body 1 is made of a metal foil-containing flexible laminated sheet 3 that can be bent and deformed without creating creases. 4 and 4' are overlapped and joined to form a body joint 5. As is clear from FIG. 3, which shows a cross section of the laminated sheet 3, it is important that the laminated sheet 3 contains the metal foil 6 in terms of prevention of wrinkles and gas barrier properties when deformed. The laminated sheet 3 also has an inner surface layer 7 and an outer surface layer 8, each of which is made of a heat-sealable thermoplastic resin, so that overlapping bonding by heat sealing is possible. . Although not necessarily required, in the specific example shown in the accompanying drawings, a layer 9 of paper or synthetic paper is provided on the outside of the metal foil 6, and each of these layers is bonded together via an adhesive layer 10. . Laminated sheet 3 for forming a container body used in the present invention
Although it is possible to bend and deform when used as a container body, it must not cause creases.
Now, when the flexible container body is deformed indentation due to a pressure difference, the following two deformations can be considered as this deformation. One of these is the so-called bending deformation shown in Figure 8-A.
2 will remain as folds even when the container body 1 recovers from its deformation. Another deformation is what can also be called a bending deformation as shown in FIGS. 7 and 8-B. In this case, bending occurs in the sheet constituting the trunk 1;
A crease as shown in FIG. 8-A does not occur, and therefore no crease remains after the deformation is recovered. In the present invention, as the body 1, a cylindrical sheet molded product that can be bent and deformed as shown in FIG. 8-A is used. That is, the metal foil 6 has a thickness of 9 to 50 μm.
The laminated sheet 3 has a total thickness of 200 to 500 μm and a weight of 100 to 400 kg/
It has an elastic modulus of mm ² . Furthermore, in general, the smaller the diameter of a flexible container body, the greater the force with which it can withstand deformation under reduced pressure, but on the other hand, once deformation occurs, there is a greater tendency for bending deformation to occur. From this point of view,
For the purpose of the present invention, it is desirable for the diameter of the container body to be between 30 and 100 mm. As shown in FIGS. 4 and 6, the lid 2 used in the present invention is constituted by a metal foil-containing covering sheet 14 having at least one central portion 13 that can be deformed by jumping. As shown in the enlarged cross-sectional view of FIG. 6, this covering sheet 14 consists of a metal foil substrate 15 and resin-coated protective layers 16 and 17 applied to both surfaces thereof. These covering protective layers 16, 17 are
It may be a thermoplastic resin film layer or a protective resin coating, and from the viewpoint of sealing engagement by heat sealing, which will be described in detail later, the inner protective layer 16 is preferably a heat-sealable film layer. In this case, the inner protective film layer 16 is bonded to the metal foil substrate 15 via an adhesive layer 18. This lid body 2 has a ring-shaped U-shaped groove 1 around it.
9, and the open end edge 20 (see FIG. 1) of the body 1 is inserted into this U-shaped groove 19 so that a sealing engagement between the two is achieved. The center portion 13 of the lid body 2 bulges outward (upward in the figure) in a dome shape from the annular rim 21 inside the front U-shaped groove 19, and uses the annular rim 21 as a fulcrum. It is now possible to jump and deform. In this specification, the jumping deformation refers to the deformation in which the wall surface suddenly jumps from a certain position to another position when the load exceeds a certain limit value. For example, in FIGS. 4 and 5, the dome This means a deformation in which the central portion 13 jumps from the upward protruding position shown in FIG. 4 to the downward protruding position shown in FIG. 5, which is symmetrical with respect to the plane including the fulcrum 21. The ease with which this jumping deformation occurs also varies depending on the thickness of the metal foil and the degree of protrusion of the dome. That is, if the metal foil is too thin, normal deformations other than jump deformation are likely to occur, while if it is too thick, the deformation itself becomes difficult. From this point of view, in the present invention, the thickness of the metal foil 15 of the lid is 50 to 50 mm.
It is important that the diameter be within the range of 120 μm, and the extent of the bulge in the center, that is, the ratio of bulge height/diameter, is between 0.05 and 120 μm.
It is important that it is in the range of 0.2. Manufacturing process of canned goods The manufacturing process of the present invention will be explained using Figures 9-A to 9-E. First, in the step shown in FIG. 9-A, the lid 2a is hermetically engaged with the lower end of the container body 1 by heat sealing to prepare a container with only the upper end open. Next, in a hot filling step shown in FIG. 9-B, the contents 22 are filled into the container 1a hot, for example at a temperature of 65 to 96°C. In the sealing process shown in Figure 9-C, the container 1a
The lid body 2b is fitted onto the upper end of the lid body 2b, and both are sealed by heat sealing, for example, by heating from the high frequency induction heating mechanism 23 or the like. In the cooling process shown in Figure 9-D, the sealed package 24
If necessary, further heat sterilize and cool.
In this cooling process, the pressure inside the container is reduced as the volume of the contents decreases, and a concave deformation 26 occurs in the container body due to the pressure difference inside and outside the container. In the present invention, as shown in FIG. 9-E, in this case, the lids 2a and 2 of the container are
By applying an axial load 28 to b, the central portion 13 is deformed inwardly, thereby restoring the concave deformation of the body portion to its original state. In the present invention, since the body is made of a flexible material that is more easily deformed than the lid, the body undergoes concave deformation as the hot-filled package cools. However, by forming the body into a cylindrical body that can be bent and deformed, forming a central part on the lid body that can be deformed by jumping inward, and deforming this central part during or after cooling, the container body can be The dented deformation is restored to its original state without leaving creases, and the appearance of the packaged can is maintained in an excellent condition.
It is possible to effectively eliminate the tendency for the storage stability and strength of the container to decrease due to deformation. The invention is illustrated by the following example. (Example) A 60 μm unstretched polypropylene film and a soft aluminum foil were subjected to sandwich lamination via maleic anhydride-modified polypropylene. The resulting composite film and unstretched polypropylene of 150 μm were subjected to sand-deutsche lamination via maleic anhydride-modified polypropylene.
A composite sheet containing five layers of aluminum foil was obtained.
The maleic anhydride-modified polypropylene of the resulting composite sheet had a diameter of about 15 μm. Aluminum foils having various thicknesses were used as shown in Table 3. This composite sheet was cut into rectangles using a punch-type cutting machine, rolled up so that the unstretched polypropylene of 60 μm was on the inside, and then stacked so that the edges of the short sides faced each other using an induction heating pressure bonding method. , the inner diameter is
A cylindrical can body measuring 52.5 mm and 137 mm in height was molded. Separately, a 30 μm unstretched polypropylene film and an aluminum foil were subjected to sand German lamination via maleic anhydride-modified polypropylene. The obtained composite film and unstretched polypropylene of 30 μm were subjected to sandwich lamination via maleic anhydride-modified polypropylene.
A composite sheet containing five layers of aluminum foil was obtained.
The maleic anhydride polypropylene layer of each of the resulting composite sheets had a thickness of 12 μm. Aluminum foils having various thicknesses were used as shown in Table 3. This composite sheet was press-molded into a lid having a U-shaped groove at the periphery and a dome-shaped portion bulging outward at the center.
At this time, lids were molded in which the degree of bulge, that is, the ratio of bulge height/diameter was varied as shown in Table 3. Next, a lid is engaged with one end of the can body obtained in this manner by induction heating, and 250 g of water at various temperatures as shown in Table 3 is quickly filled, and the can body and other parts are heated. Identical lids were similarly engaged and sealed on the ends. The obtained canned product was left at room temperature and cooled to room temperature. An axial load was forcibly applied to the upper and lower lids of the canned container, in which the body thus obtained had been deformed under reduced pressure, to restore the deformation of the body. In addition, for some canning cases, a load was forcibly applied to the upper and lower lids in the axial direction immediately after engagement and sealing, that is, without cooling, to cause the lids to deform. Third
The results are shown in the table.

【table】

【table】 [Brief explanation of the drawing]

Fig. 1 is an external view of the body of the container used in the present invention, Fig. 2 is a horizontal sectional view of the body, Fig. 3 is a sectional view of the material composition of the body, and Fig. 4 is a sectional view of the lid used in the present invention. 5
The figure is a cross-sectional view of the lid showing that the central part of the lid has undergone jump deformation, Figure 6 is a cross-sectional view of the material composition of the lid, and Figure 7 is an external appearance showing that the body has undergone bending deformation. Figure 8-A is a horizontal cross-sectional view of the body that has undergone bending deformation, Figure 8-B is a horizontal cross-sectional view of the body that has undergone bending deformation, and Figure 9-A is prepared during the manufacturing process of the baquium can. a container with a lid engaged at one end of the body,
Figure 9-B is the filling process, Figure 9-C is the sealing process,
Figure 9-D shows a cooling process in which the body is deformed under reduced pressure, and Figure 9-E shows a process in which the lid jumps and deforms. 1, 1a...Flexible trunk, 2, 2a, 2b...
Lid, 3... body laminate, 4... body laminate end edge, 5... body seam, 6... metal foil, 7... heat sealable resin, 8... heat sealable resin, 9
... Paper substrate, 10 ... Adhesive, 11 ... Seam correction agent, 12 ... Crease, 13 ... Dome-shaped central part of lid, 14 ... Lid laminate, 15 ... Metal foil, 16 ...
...Heat sealing resin, 17...Protective film, 18...
... Adhesive, 19 ... U-shaped groove, 20 ... Open edge of body, 21 ... Jumping deformation fulcrum, 22 ... Contents (filling), 23 ... Induction heating mechanism, 24 ... Sealed package (canned), 25...filling nozzle, 27...
Compression jig for the dome-shaped central part of the lid, 28...Load and load direction.

Claims (1)

[Scope of Claims] 1. In a method for manufacturing a baquium can using a body and a lid made of a flexible material; 100 to 400 at 500μm
Using a cylindrical molded product of a flexible laminated sheet containing metal foil, which has an elastic modulus of Kg/mm ² and can be bent and deformed without producing creases; As a lid, a metal foil with a thickness of 50 to 120 μm is used. It is made of a foil-containing covering sheet, and has a ring-shaped U-shaped groove around which the open end of the body is inserted for sealing engagement between the two, and a dome-shaped bulge extending outward in the center of the ring-shaped groove. using a lid having a jump-deformable central part with a bulging height/diameter ratio in the range of 0.05 to 0.2; hot filling the container comprising the body and the lid; At the same time, the container is sealed; the obtained canned product is cooled; and after cooling, the center part of the lid of the canned product is pressed inward to forcibly jump and deform the lid center part. A method for making canned baquium, which consists of a sex container.