JPH0698969B2 - Method for manufacturing sealed container - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a hermetically sealed container which is filled with food or the like and is not erroneously recognized as an expansion container even if a Strecker decomposition occurs.

(Prior art) Contents containing proteins, sugars, and starches such as foods stored in a sealed container are decomposed by Strecker (oxidative decarboxylation reaction during retort heat sterilization treatment of proteins and sugars and during storage). However, unlike spoilage caused by bacteria, there is no problem in hygiene) to generate carbon dioxide.

Therefore, since the internal pressure of the container increases due to Strecker decomposition, if the container has a wall portion that easily expands due to this increased internal pressure, the wall portion bulges out, so-called an expansion container (when the food contents rot, the generated gas is a sealed container. Since it expands, it is generally presumed that the food in the expansion container is putrefaction).

In order to avoid this misidentification, the internal pressure of the sealed container before the retort sterilization treatment should be set to a negative pressure (pressure lower than atmospheric pressure) that is not likely to be mistaken for an expansion container even if Strecker decomposition occurs. Is preferred.

Conventionally, as means for making the internal pressure of the sealed container a negative pressure, (a) filling the contents in a vacuum, a sealing method, and (b) filling the contents, mainly for removing oxygen from the space A method in which steam from a boiler is blown into the container body by a nozzle with a narrow mouth to replace air in the space and then sealed.
(C) A so-called hot pack method or the like has been employed in which liquid foods such as juices heated to about 80 to 90 ° C are filled into the container body and then immediately sealed.

However, the vacuum method (a) has problems that the apparatus is complicated, the equipment cost is relatively high, the workability is poor, and it is not suitable for high-speed production.

In the steam method of (b), it is difficult to control the amount of steam to be blown in and the steam pressure. When applied to the semi-rigid container described below, the required negative pressure is small, so a nozzle with an extremely narrow mouth is used. In that case, the nozzle is likely to be clogged with water droplets or foreign matter (due to scale in the pipe), and as a result, the fluctuation range of the negative pressure is large.

Therefore, the container has, for example, a self-shape in an unloaded state, and the depression of the wall portion (for example, the low wall portion) due to a slight internal negative pressure (for example, gauge pressure −7 cmHg) can be substantially restored.
It is an elastic dent deformation that does not lose the commercial value, but a relatively high internal negative pressure (for example, gauge pressure −20 cm).
This method is used when the wall (for example, the trunk wall) is of a type that contracts or deforms or is crushed to the extent that it loses its commercial value due to Hg) (hereinafter, this type of container is called a semi-rigid container). In this case, there is a problem that the product value may be lost due to a negative pressure being erroneously recognized as a so-called expansion container, or an excessive negative pressure causing a serious contraction deformation.

The hot pack method of (C) can be applied only to liquid foods,
For example, it cannot be applied to solid foods such as sausages, and even in the case of liquid foods, when it is applied to a semi-rigid container, there is a problem that shrinkage deformation during cooling is so great that commercial value is lost.

(Problems to be Solved by the Invention) In the present invention, the internal negative pressure is controlled to such an extent that the contents such as foods are filled and there is no possibility of being mistaken for an expansion container even if Strecker decomposition occurs. An object of the present invention is to provide a method for manufacturing a sealed container such as a semi-rigid container with relatively low cost and high productivity.

(Means for Solving Problems) A method for manufacturing a hermetically sealed container according to the present invention is a container having a wall portion that is filled with contents leaving a space and elastically dents and deforms depending on an internal negative pressure degree. The step of spraying water vapor generated by blowing a non-condensable gas at a predetermined flow rate into the main body at a constant temperature, the step of sealing the container body with a lid, and the amount of dent deformation of the wall portion after sealing Is characterized in that the step of measuring is performed on the same line.

The wall that elastically dents and deforms depending on the internal negative pressure is
As the internal negative pressure increases, the amount of deformation of the dent increases, and when the internal negative pressure returns to 0, the amount of dent deformation also returns to substantially 0. It refers to the wall portion (such as the body wall portion or the bottom wall portion) whose internal negative pressure can be obtained from the amount of deformation.

(Operation) Water vapor generated by blowing a predetermined flow rate of non-condensable gas into water whose temperature is controlled is sprayed onto the container main body filled with the contents, leaving a space.

Since the amount of steam to be sprayed is determined only by the water temperature, the flow rate of the non-condensable gas, and the spraying time, it is easy to control the amount of steam with a small fluctuation range. Therefore, even if the sealed container is a semi-rigid container, its internal negative pressure is not likely to be mistaken for an expansion container even if Strecker decomposition occurs, and the wall portion loses its commercial value. It is possible to control within a range that does not shrink, deform, or collapse.

The container body has a wall that is elastically dented and deformed depending on the internal negative pressure, and the amount of dented deformation of this wall is measured on the same line after sealing. You can see the negative pressure.

Therefore, even if production is performed without noticing an accident in the steam generator, the internal negative pressure can be detected and repaired by detecting that the internal negative pressure exceeds a predetermined range. It is possible to resume production of sealed containers within a predetermined range.

In addition, a defective container having a pinhole or the like penetrating the inside and outside of the lid portion or the sealing portion and having no hermeticity is detected as an internal negative pressure degree of 0. In addition, a container that has been crushed due to excessive internal negative pressure is detected as having an excessive internal negative pressure. By rejecting the containers whose internal negative pressure is out of the predetermined range from the line, only the sealed container whose internal negative pressure is within the predetermined range and whose sealing property is confirmed can be delivered from the line.

Since steam may be sprayed in the atmosphere, workability is good, and since each step is carried out in the same line, productivity is high because of continuous production by line work.

The equipment is relatively inexpensive because it mainly consists of a water constant temperature control device and a non-condensable gas constant flow rate blowing device.

(Example) In FIG. 1, reference numeral 1 denotes a cup-shaped semi-rigid container body formed by drawing a blank of a laminated body having inner and outer layers made of polypropylene film and a central layer made of metal foil. Reinforcing bead 2a on the periphery
Are formed. The container body 1 is filled with the contents (mainly food) at around room temperature (usually about 5 to 40 ° C.), leaving the space 3.

Each container body 1 is supported in the flange portion 2 by the support 5 at a predetermined interval d, and is transferred in the direction of arrow A while performing intermittent motion (for example, stop 2 seconds, transition 1 second) at a predetermined timing. .

Reference numeral 6 denotes a steam generator, which includes a water tank 7, an air blowing pipe 9 having a flow meter 8, a steam blowing pipe 10, and a thermometer 11. Reference numeral 12 is a water pipe for supplying water 13 to the water tank 7 before the start of work, 14 is a drain pipe for maintaining a constant water level and forming a head space portion 17 of a predetermined volume, and 15 is for draining water after the end of work. Pipe, 16 is a steam trap.

The air blowing pipe 9 has an air source (not shown).
1.5kg / cm ² ), filter 18, manual flow control valve 19
Air of a predetermined flow rate (for example, 5 l / min) is sent through the air, and the air is blown from the blowout holes 9a. Note that non-condensable gas such as nitrogen gas may be used instead of air.

The steam blow pipe 10 includes a temperature controller 21 connected to a pressure reducing valve 20 and a thermometer 11 from a boiler (not shown).
Steam (for example, 0.7 kg / cm ² , 115 ° C.) is sent through the on-off valve 22 that is turned on and off based on the signal of, and steam is blown from the blowout hole 10a. 23 and 24 are manual on-off valves.
The steam keeps the temperature of the water 13 in the water tank 7 at a predetermined temperature (for example, 91 ± 0.5 ° C.).

A steam pipe 27 (preferably made of stainless steel) is connected to the head space portion 17 of the water tank 7. Steam pipe 27
The flow rate of the steam 40 discharged through the water is controlled by the water temperature of the water tank 7 and the flow rate of air blown from the air blow pipe 9.

On the downstream side, the steam pipe 27 branches into two vertical steam branch pipes 28 and 29 with a space of d. The steam pipe 27 and the steam branch pipes 28 and 29 are wound with heater coils 30 and 31 and covered with a heat insulator 32. The steam temperatures at the open ends 28a 'and 29a' of the steam branch pipes 28 and 29 are controlled by the thermometer 33, controller 34, thermometer 35, and controller 36 to a predetermined temperature (preferably 101 to 110).
C .; for example 105.degree. C.).

A vertical blow-in pipe 37 of an inert gas is arranged at a position of a distance d on the downstream side of the steam branch pipe 29. 38 is a flow meter. Nitrogen gas is preferably used as the inert gas, but carbon dioxide or other inert gas may be used. An inert gas at room temperature is usually blown from the open end 37a 'of the inert gas blowing pipe 37.

The lower ends 28a, 29a and 37a of the steam branch pipes 28 and 29 and the inert gas blowing pipe 37 respectively have a support plate 2 having a flat bottom surface 25a.
It is formed by each vertical hole provided in 5. The inner diameter of the open end 28a ', 29a' of each steam branch pipe 28, 29 is usually 4 to 10 mm. The support board 25 is provided with a heating element (not shown) (for example, a steam pipe or an electric resistance heating element), and the temperature near the bottom surface 25a thereof is preferably kept at about 105 ° C.
This is to prevent condensation.

A heat sealer 44 of the lid 43 is arranged downstream of the inert gas blowing pipe 37 with a center interval d. 45 is a hot plate for heat sealing. The portion of the strip-shaped film or web 47 unwound from the laminated body coil 46, which is placed on the flange portion 2 of the container body 1 via the guide roll 48, becomes the lid portion 43. As the laminate, for example, one having inner and outer layers made of polyethylene terephthalate film and polypropylene film and a central layer made of metal foil is used.

The container body 1 is sprayed with water vapor 40 while it is stopped below the steam branch pipes 28 and 29 and while passing below. Thereby, most of the air in the space 3 is replaced with water vapor, and the contents 4 are heated to preferably 50 ° C. or higher, but since the total blowing time is very short (for example, about 4 seconds)
It is heated near the surface of the contents 4 (for example, 0 from the surface).
~ 1mm thick) only). Moisture is condensed on the surface of the contents 4.

Immediately thereafter, the container body 1 is transferred below the inert gas blowing pipe 37 and stopped. During this time, 51
And the residual air is replaced by the inert gas 51 in the space 3. Since the inert gas 51, especially the nitrogen gas, has a very small heat capacity, the heating of the contents 4 by the blowing hardly occurs.

The container body 1 is then transferred below the heat sealer 44,
Stop, heat seal the lid 43 to the flange 2,
It becomes a sealed container 52. In the next step, the lid 43 is cut from the web 47 by the cutter 60. The web 47a of the dregs having the lid 43 punched out is formed by the winder 1 (not shown).
It is wound up by 1 and becomes scrap.

Although most of the water vapor in the space 3 is removed by the above-mentioned inert gas replacement, it is condensed on the heated surface of the contents 4 within a short time until it moves below the heat sealer 44. The water having a relatively high temperature evaporates (the surface of the contents is deprived of latent heat to cool), and the space 3 becomes an atmosphere of water vapor and an inert gas, but the water vapor partial pressure is relatively low ( For example, 11 to 15 cmHg). Therefore, in the space portion 3 of the sealing container 52, the negative pressure generated by the condensation of the water vapor is slight, and the lid portion 43 and the bottom wall portion 1a of the container body 1 which are relatively flexible in order to reduce this negative pressure are illustrated. Although it is slightly recessed as described above, the body wall portion 1b is not substantially deformed.

In the next step, the sealed container 52 is eddy current distance sensor 62.
After sliding on the slide 61 provided with, in the stopped state, the maximum recess depth h of the bottom wall 1a (level difference between the peripheral annular protrusion 1a _{1 of the} bottom wall 1a and the central portion 1a ₁ ; the recess is Based on elastic deformation). The output signal of the sensor 62 is input to the comparator 63, and the depth of the comparator 63 is lower than h ₁ (insufficient internal negative pressure) or higher than h ₂ (may be crushed due to excessive internal negative pressure). Yes; reject signal when h ₂ > h ₁ )
Output 64.

For example, h ₁ and h ₂ are defined as follows. Bottom wall before sealing
1a has a recess depth h '(refer to the rightmost container body 1 in the figure) of 0.3 ± 0.05 mm, which causes crushing due to excessive internal negative pressure of the sealing container 52. H is 1.3 mm
In the above case, h ₁ is 0.5 mm and h ₂ is 1.1 mm.

In the next step, the sealed container 52 is pushed up by the lifter 64 and sent out from the support tool 5. At that time, a normal container 52 of h ₁ h ₂ is moved forward by the conveyer in front of the drawing by a pusher (not shown). A defective container 52 with h <h ₁ or h <h ₂ pushed out (not shown) is rejected
Based on 64, it is extruded onto a conveyor (not shown) behind in the direction of the drawing. The recess depth h may be measured by a magnetic sensor, an optical sensor, a mechanical sensor, or the like.

The present invention is not limited to the above embodiments,
For example, depending on the type of the contents 4, or when an inert gas such as nitrogen gas is blown from the blow pipe 9, a device provided with a heat sealer 44 at the position of the inert gas blow pipe 37 is used. The steam may be sprayed in the same manner as described above, except that the step of spraying the inert gas 51 is not performed. Further, one hot plate 45 may be provided and heat sealing may be performed twice. Further, a step for cooling the heat-sealed portion may be provided between the final heat-sealing and the lid cutting.

(Specific Example) A specific example will be described below.

A temperature controller that controls the ON / OFF state of the on / off valve 22 of the steam blow pipe 10 (steam temperature 115 ° C), using the water temperature of the water tank 7 (internal volume 5000cc, headspace 17 volume 2000cc) of the type shown in Fig. 1. The temperature is set to 92 ° C by 21 and air is blown into the water tank 7 at a flow rate of 5 Nl / min (source pressure 2.0 k
g / cm ² ) was sent. In this case, 12.3 g of steam 40 is generated every minute.

On the other hand, a blank of a laminated body consisting of polypropylene with an inner and outer surface layer having a thickness of 50 μm and a central layer made of rolled steel foil with a thickness of 75 μm was drawn to form a body wall with an upper outer diameter of 65 mm, a lower outer diameter of 56 mm, and a height of 30 m.
A cup-shaped container body 1 having a flange portion of m and an internal volume of 35 ml was produced. While supporting the flange portion 2 of the container body 1 by the support tool 5 and performing intermittent movement (stop for 2 seconds, movement for 1 second) 20 times per minute, 35 g of fish meat 4 is added to each container body 1.
Was filled.

The container body 1 is moved in the direction of arrow A as shown in FIG. 1 and stopped when it reaches below the steam branch pipes 28 and 29, so that water vapor 40 is introduced into the container body 1 from the open ends 28a ′, 29a ′. Sprayed. The height of the gap between the bottom surface 25a of the support board 25 and the flange portion 2 is 5 mm, and the distance d between the central axes of the steam branch pipes 28 and 29 is 120 mm.
Met.

Next, after blowing nitrogen gas at room temperature at 5 l / min from the open end 37a 'of the inert gas blowing pipe 37, immediately put the lid portion 43 on the flange portion 2
It was heat-sealed and sealed. The inner layer of the lid 43 is thick
50 μm polypropylene, middle layer 20 μm thick aluminum foil, outer layer 12 μm biaxially oriented polyethylene.
The laminate web 47 was made of terephthalate.

After heat-sealing, the heat-sealed portion was cooled, and then the lid 43 was punched. Then, as described in the example,
The maximum recess depth h was measured. In the case of this container, the depth h
However, when 0.5mm, the internal negative pressure is -2cmHg, and when 1.1mm, it is -16cmHg, h <0.5mm or h> 1.1mm.
In case of, the reject signal 64 is output.

200 containers 52 were manufactured as described above, and it was confirmed that h was in the range of 0.5 to 1.1 mm, the depressurized state was appropriate, and the sealing was good.

20 containers 52 were manufactured in the same manner as described above except that a pinhole having a diameter of 0.2 mm was intentionally formed in the lid 43, and reject signals 64 were output for all of them and rejected.

(Effects of the Invention) According to the present invention, a semi-rigid container in which contents such as food are filled and whose internal negative pressure is controlled to the extent that it is not mistaken for an expansion container even if Strecker decomposition occurs It is possible to manufacture such a sealed container with relatively low cost and high productivity.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view for explaining an example of an apparatus for carrying out the method of the present invention. 1 ... Container main body, 1a ... Bottom wall (wall that elastically dents and deforms), 3 ... Space, 4 ... Contents, 9 ... Air blowing pipe, 8 ... Air flow meter, 13 ...... Water, 21 ...... Temperature controller, 40 ...... Steam, 43 ...... Lid part, 44 ...... Heat sealer,
52 …… sealed container (sealed container), 62 …… eddy current type distance sensor.

Claims (1)

[Claims] 1. A container main body which is filled with a content leaving a space and has a wall portion which is elastically dented and deformed depending on the internal negative pressure, in a constant temperature controlled non-condensation flow in water. Characterized in that the step of spraying water vapor generated by blowing a volatile gas, the step of sealing the container body with a lid, and the step of measuring the amount of dent deformation of the wall portion after sealing are performed on the same line. Method for manufacturing sealed container