JPS6220084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hermetically sealed packaging method using a cup-shaped deep-drawn container suitable for heating filling and retort sterilization of liquid foods and the like.

[Conventional technology]

In particular, in the present invention, the deep drawn container has a depth to diameter ratio of 1 or more. In a shallow container with a ratio of 1 or less, there is little deformation due to heat treatment during or after filling.
This is because the height of the container is low and the container is rigid, so the deformation is not noticeable when there is no head space, and when there is a head space, the deformation can be made less noticeable by devising the design of the side wall. However, in the case of a shallow container, there is a feeling of loss, so filling without head space is common.

In any case, in a shallow container, heat treatment can be performed using conventional techniques without noticeable deformation. Deep-drawn containers with a molding depth to diameter ratio of 1 or more are suitable as containers for liquid foods.

Glass bottles have been used for a long time as containers for liquid foods such as alcoholic beverages and youth drinks, but glass bottles have disadvantages such as being fragile and heavy, so lightweight liquid containers that can replace glass bottles have recently been attracting attention. There is. Metal cans such as aluminum and tin cans are widely used as lightweight liquid containers, but since metal cans are difficult to reuse or incinerate, the disposal of empty cans after use has become a social issue. Plastic containers or paper-plastic composite containers are lightweight, economical,
Because they are easy to incinerate after use, they are excellent not only for liquid foods but also as containers for solid foods, and in recent years they have increasingly been replaced by glass bottles and metal cans.

[Problem that the invention seeks to solve]

In order for plastic containers and paper-plastic composite containers to become more popular as food containers, it is desirable to reduce the thickness of plastic containers within a range that does not impair performance in terms of resource and energy conservation. Making it thinner will reduce the weight, but it will also reduce the rigidity.
The so-called strength of the lower back is lost. Therefore, after filling a thin-walled plastic container with contents, sealing the mouth with a lid material and performing pressure heat sterilization treatment in hot water, so-called retort treatment, the internal pressure of the container increases and the top and bottom of the container The bottom may expand outward and the container may remain deformed even after cooling. If the bottom of the container, which should originally be flat or concave inward, bulges outward, it will not be able to stand on its own and will become unstable. In addition to the expansion of the bottom, the lower part of the side wall of the container may also be deformed. When the bottom of a deep-drawn, thin-walled plastic container swells during retort processing, its stability is significantly impaired, making it more likely to topple over, deteriorating its appearance, and losing the commercial value of its contents.

After heating liquid foods such as alcoholic beverages and youth to around 60 to 90 degrees Celsius in a thin-walled plastic container,
Inject and fill the container to about 80% to 90% of its volume.
If the mouth is sealed leaving a so-called head space and then the container is cooled, the side wall of the container will become depressed and the appearance will be poor. In the case of a container with a cylindrical side wall, the container will have an unsightly appearance, especially if a portion of the side wall is recessed. In this way, when heating and filling a liquid food and sealing the mouth while leaving a head space, the container is particularly prone to denting, mainly because the hot air trapped in the head space while still being heated cools down. This is because the pressure inside the container becomes negative compared to atmospheric pressure.

〔the purpose〕

The purpose of the present invention is to prevent the appearance of the container from deteriorating due to deformation even if the container is sterilized by boiling or retort after filling and sealing the contents, such as food, and which has waterproof, preservative, and gas barrier properties. It is an object of the present invention to provide a hermetically sealed packaging method using a container having a good and high rigidity.

[Means for solving problems]

The present inventors have developed a case where liquid food is heated and filled into a pop-shaped thin-walled polypropylene container while leaving about 10% of the required head space, the mouth is sealed with a lid material, and the sealed container is cooled. Further, the deformation of the sealed container was observed in detail when the container was further subjected to boiling sterilization treatment or retort sterilization treatment. As a result, when the wall thickness of the side wall of a container is about 0.2 mm, the side wall of the container is unevenly depressed due to the reduced pressure inside the container, but in the case of a polypropylene container with a wall thickness of about 0.1 mm, cooling causes the side wall of the container to dent. They discovered that even when the pressure inside the container is reduced, the dents on the side wall of the container are not noticeable, and after further study, they have completed the present invention.

The sealed packaging method of the present invention has a flange portion at the open end, and the molding depth to diameter ratio is 1.0 or more,
A concave inner molded product A made of polypropylene resin, in which the inner diameter of the bottom is equal to the inner diameter of the opposite diameter, or the inner diameter of the opening is slightly larger than the inner diameter of the bottom, and the average wall thickness d of the cavity is 0.15 mm or less. After filling the molded product A with the contents, the opening of the molded product A is sealed with a lid having a size larger than the opening area of the molded product A, and then the sealed molded product is boiled or retorted, and then The opening end has a flange, the molding depth to diameter ratio is 1.0 or more, the inner diameter and molding depth are equal to or slightly larger than the inner molded product A, and the average wall thickness of the cavity D The hermetically sealed molded product is fitted into an outer molded product B whose main component is thermoplastic plastic or paper and whose average wall thickness d is equal to or greater than the average wall thickness d of the cavity of the molded product A, and the inner molded product A and the outer molded product are separated. B
The flange portions of the inner molded product A and the outer molded product B are adhered to each other or the lid material and the flange portions of the inner molded product A and the outer molded product B are bonded to each other, thereby sealing the gap between the two molded products.

[Action of the invention]

The method of the present invention will be explained below with reference to the drawings.

FIG. 1 shows an example of the sealed packaging method of the present invention. First, the inner molded product 2 having the flange portion 1 at the opening end shown in a is filled with the contents 3 as shown in b, and then the lid material 4 is placed on the opening of the molded product as shown in C. The peripheral part of the lid material 4 is heat-sealed with the upper surface 5 of the part, and then, as shown in d, this sealed molded product is put into a retort processing device 6 and boiled or retorted with hot water 7, and then shown in e. The sealed molded product is fitted into the outer molded product 8 as shown in FIG. Seal tightly. In this example, there is a head space 11 in the upper part of the closed molded part 9, and the bottom part 12 of the outer molded part 8 is heated during the heat sealing shown in f.
In this case, the head space 11 for pushing up the bottom part 13 of the sealed molded product 9 is slightly reduced.

2 to 4 show an example of a container used in the sealed packaging method of the present invention. FIG. 2 shows a row of sealed molded products in which the inner molded product A is hot-filled with liquid food and then the mouth portion is heat-sealed with a lid. Hot-fill the liquid food 15 into the inner molded product 14, place the lid 17 on the mouth with the head space 16 left, and close the lid 17 with the flange 18 of the inner molded product 14.
Heat seal. In this case, the area of the lid material is slightly larger than the peripheral area of the flange part, and the peripheral area of the lid material 1 is placed around the flange part 18.
Leave 9. FIG. 3 shows the outer molded product 20, and the average wall thickness of the cavity is the inner molded product 14 in FIG.
The wall thickness of the flange portion 21 is equal to or greater than that of the flange portion 21.
The upper surface is lower than the outside by the thickness of the flange portion 18 of the inner molded product 14. FIG. 4 shows the inner hermetically sealed molded product that has been subjected to boiling or retort treatment inserted into the outer molded product 20.
The upper surface 22 of the flange portion of No. 0 and the peripheral portion of the lid member are heat-sealed. In the case of this example, if materials with high gas barrier properties are used for the lid material 17 and the outer molded product 20, the gas barrier properties of the entire container can be significantly improved since the container mouth can be sealed well.

Inner molded product A has a flange at the opening end, the ratio of molding depth to diameter is 1.0 or more, and the inner diameter of the bottom and the inner diameter of the opening are equal, or the inner diameter of the opening is slightly larger than the inner diameter of the bottom. It is a large, concave container made of thermoplastic plastic with a thin average wall thickness d in the cavity. Although the shape of the flange portion at the opening end is not particularly limited, the flange portion is necessary in order to seal the mouth portion with the lid material. The molding depth to diameter ratio is 1.0 or more, and is particularly preferably in the range of 1.0 to 3.0. Containers with a molding depth to diameter ratio of 1.0 or less have fewer problems with their self-supporting properties, appearance, etc., and the effects of the present invention are not noticeable. The average wall thickness d of the cavity is thin, 0.15
It is preferable that mm≧d≧0.02 mm.
When a liquid content is filled into a molded article A whose cavity has such a thin average wall thickness, the wall surface of the container can be freely deformed even after the mouth is sealed. The container deforms with a small amount of force, but it also has the ability to stand on its own to some extent and maintain its shape. As a method for molding a container from polypropylene resin, it is preferable to mold a polypropylene resin sheet by air pressure molding. In particular, solid phase air molding is preferred for molding a deep container with good transparency. Containers manufactured from polypropylene sheets by solid phase air forming have good transparency, and it is easy to obtain deep-drawn containers.
If the container is heated to a temperature of about 90° C. and filled with hot water, then the mouth is sealed and sterilized by boiling or retort, the side wall of the container is likely to become dented or constricted, resulting in poor appearance. This is because the internal pressure of the container decreases due to sealing after hot filling, and also because the container shrinks and deforms during boiling or retort processing. These deformations are particularly noticeable when the head space above the closed molded part is large. This deformation is noticeable when the average wall thickness of the side wall of the container is large, but this deformation is not necessarily noticeable when the average wall thickness of the side wall is thin. In the case of a container with a thin side wall, the water pressure of the filled liquid food applies a uniform force from the inside of the container to the side wall, and the side wall of the container, which can deform freely, does not deform unevenly and is kept uniform in a well-balanced manner. This is thought to be due to deformation. However, a closed container alone is weak and inconvenient to handle, and is not practical.

If the inner molded product A is a container made of a high gas barrier resin with a multilayer structure of polypropylene/adhesive polyolefin/saponified ethylene-vinyl acetate copolymer resin/adhesive polyolefin/polypropylene, after filling with liquid food and sealing it. ,100℃
If the retort treatment is performed in hot water at the above-mentioned high temperature, the gas barrier resin in the intermediate layer may absorb water and whiten, and the gas barrier properties may deteriorate. Therefore, it is not preferable to use such a high gas barrier resin for the inner molded product A. The method of the present invention makes it possible to avoid retort treatment of the gas barrier layer even in gas barrier containers. In that case, the use of a saponified ethylene-vinyl acetate copolymer resin may be avoided for the inner molded product A, and a material with high gas barrier properties may be used for the outer molded product B, which is not subjected to retort treatment. Although the contents to be filled into the inner molded product A are not particularly limited, the effect of the present invention is remarkable in filling liquid foods, especially hot filling. Although the filling amount is not particularly limited, the effect of the present invention is particularly remarkable when the molded article A is filled to about 90% of its volume, leaving a head space.

The lid material may be aluminum foil, aluminum foil/plastic laminate, plastic film, plastic molded product, aluminum foil molded product, etc., and is not particularly limited, but materials with high gas barrier properties and resistance to boil sterilization or retort sterilization are preferred. The lid material needs to be large enough to sufficiently seal the mouth of the inner molded product A. When sealing the lid material and the flange portion of the molded article A, heat sealing is preferred as the sealing method.

The sealed molded product is boiled or retorted. The temperature of the boiling treatment is preferably 80°C to 100°C, and the temperature of the retorting treatment is preferably 110°C to 150°C. In particular, deformation of the sealed molded product becomes noticeable when retorting for about 30 minutes at a temperature of 115°C or higher, but by fitting this molded product into the outer molded product B, the deformation of the inner molded product A is corrected. and improves appearance.

Molded product B in appearance has a flange portion at the opening end,
The molding depth to diameter ratio is 1.0 or more, the inner diameter and molding depth are equal to or slightly larger than the inner molded product A, and the average wall thickness D of the cavity is equal to the average wall thickness d of the molded product A. The main component is thermoplastic plastic or paper, which is equivalent to or greater than . The outer molded product B requires a flange portion because it is fitted into the sealed molded product to further seal it. Although the shape and dimensions of the flange portion are not particularly limited, it is preferable that the shape be the same as that of the inner molded product A, or that the shape and dimensions can fit snugly into the flange portion of the molded product A as shown in FIG. Preferably, the molded article B has dimensions that allow it to be tightly fitted into the closed molded article. Since hermetic molded products are flexible and can change their shape, molded product B does not necessarily have to have the same shape as the hermetic molded product, but molded product B is smaller than the volume of the hermetic molded product below the flange. Are the volumes of
Preferably, it is slightly larger. When the outer molded product B is fitted into the sealed molded product and the flange part is heat-sealed, the inner molded product A becomes the outer molded product B.
It adheres closely to the walls of the container, significantly improving the appearance of the container. If the bottom of molded product B is raised inward as shown in 12 in Figure 1, the bottom of molded product A on the inside will be pushed up as shown in 13 in Figure 1. Adhesion between molded products is further improved. In particular, when molded article B is transparent, the adhesion between the molded articles influences the appearance. The outer molded product B needs to have greater rigidity than the inner molded product A. By increasing the rigidity of the side wall and bottom of the molded product B, the shape of the hermetically sealed molded product can be corrected when the molded product is fitted into the molded product B. In order to increase the rigidity of molded product B, it is necessary to increase the average wall thickness or use a hard material with high rigidity. The average wall thickness D of molded product B is 0.2 mm≦D when the material is thermoplastic.
It is preferably within the range of ≦0.5 mm. When the material is mainly paper, it is preferably within the range of 0.4 mm≦D≦1.5 mm.

As the thermoplastic plastic for molded article B, hard resins such as polypropylene, high-density polyethylene, vinyl chloride resin, styrene resin, polyester resin, polycarbonate, and polyamide resin are preferred. Preferred methods for molding the molded product B include sheet thermoforming, injection molding, and blow molding. In particular, solid-state air pressure molded products of polypropylene sheets are preferable as outer molded products because they have excellent transparency, rigidity, and deep drawability. Since one of the features of the method of the present invention is that gas barrier properties can be maintained after boiling or retort processing, the material for molded product B is polyester, which has high gas barrier properties,
A multilayer sheet containing a polyamide or vinyl chloride resin and a resin layer with high gas barrier properties is preferred. As the multilayer sheet, a high gas barrier sheet having a composition of polypropylene/adhesive polyolefin/saponified ethylene-vinyl acetate copolymer resin/adhesive polyolefin/polypropylene is preferred.

Molded article B is not subjected to boiling or retorting treatment, and therefore does not require water resistance or heat resistance.
One of the features of the present invention is that a wide variety of materials can be used for the molded product B.

When paper is used for the molded article B, a laminate of aluminum/paper or a laminate of polyolefin/aluminum/paper is preferable as a material with high gas barrier properties. The paper is used after being formed into a paper tube, preferably a paper cup.

While molded product A has functions such as antibacterial and waterproof properties against the contents of foods, etc., and is required to have heat resistance to the extent that it does not soften or flow during boil sterilization or retort sterilization, molded product B is required to have high gas barrier properties, shape retention, rigidity, and in some cases, good appearance such as gloss and transparency.

After fitting the sealed molded product A into the molded product B, the flange portion of the molded product B and the flange portion and/or lid material of the sealed molded product are adhered to seal the gap between the two molded products. The adhesion method is not particularly limited, but methods such as heat sealing, use of adhesive, and tightening are preferred.

The shape of the lid material is not particularly limited, but a flat lid, a drop lid, etc. are preferred.

By the hermetic packaging method of the present invention, it is possible to provide a hermetically sealed package using a deep-drawn container that has excellent gas barrier properties, is highly reliable, and has a good appearance even after hot filling, boiling, and retorting of liquid foods.

If the outer molded product B is a transparent plastic molded product, attach a label to the outside of the sealed molded product or the inside of the molded product B, or place a label or paper tube in the gap between the sealed molded product and molded product B. It is preferable to fit the two molded products and bond the rear flange portions to seal the gap between the two molded products.

The shape of molded product A and molded product B is round, square, etc., and is not particularly limited, but round deep drawing molded products are particularly preferred.

Examples are shown below.

Example A round molded article A having a mouth diameter of 52 mm, a depth of 75 mm, and a flange width of 5 mm was molded from a polypropylene sheet with a thickness of 0.8 mm by solid phase pressure forming. The average wall thickness of the cavity of molded product A was approximately 0.1 mm. This molded product A
About 90% of the volume of potage soup heated to 90℃
%, and the mouth was heat-sealed with an aluminum/polyolefin laminate lid with a head space of about 5 mm left at the top. Next, as shown in FIG. 1d, the sealed molded product was placed in a retort device, retorted in hot water at 120° C. for 30 minutes, and then cooled. The sealed molded product taken out had a concave shape as it was because the inside was under reduced pressure.

Made from an extruded sheet with a multilayer structure of 2.0 mm thick polypropylene/adhesive polyolefin/saponified ethylene-vinyl acetate copolymer resin/adhesive polyolefin/polypropylene, a diameter of 52 mm and a flange width of 75 mm in depth are produced by solid phase pressure molding. A 5 mm round molded product B was molded. The average wall thickness of the cavity of molded product B was approximately 0.29 mm. The average wall thickness of the cavity of this molded product B was about 0.29 mm. The hermetically sealed molded product immediately after the retort treatment was fitted into the molded product B, and the flange portions of both molded products were heat-sealed. The container sealed in this way had good gloss, transparency, and rigidity, and had a good appearance with no whitening or dents. After storing this sealed package for three months, the contents were removed. I tried Jiyu soup. The soup had no deterioration at all and had a good taste. As a result, it was confirmed that the sealed packaged product had good antibacterial and oxygen gas barrier properties.

[Brief explanation of the drawing]

FIG. 1 shows an example of the process of the sealed packaging method of the present invention, and in the figure, 1 is the flange portion of the inner molded product A, 2 is the inner molded product A, 3 is the contents, 4 is the lid material, 5 is the upper surface of the flange part, 6 is the retort processing device, 7 is hot water, 8 is the outer molded product B, 9 is the sealed molded product, 10 is the flange part of the molded product B, 11 is the head space, 12 is the molded product B 13 is the bottom of the sealed molded product. 2 to 4 show an example of a container used in the present invention. In the figure, 14 is the inner molded product A, 15 is the liquid food, 16 is the head space, 1
7 is a lid material, 18 is a flange portion, 19 is a peripheral portion of the lid material, 20 is an outer molded product B, 21 is a flange portion,
22 indicates the upper surface of the flange portion.

Claims (1)

[Claims] 1. The opening end has a flange, the molding depth to diameter ratio is 1.0 or more, and the inner diameter of the bottom is equal to the inner diameter of the opening, or the inner diameter of the opening is larger than the inner diameter of the bottom. The inner diameter is slightly larger, and the average wall thickness of the cavity d is 0.02.
mm or more and 0.15 mm or less and is made of polypropylene resin and is heat-filled with the contents, and then the opening of the molded product A is filled with a lid material having a size larger than the opening area of the molded product A. Then, the sealed molded product is boiled or retorted, and then the molded product A has a flange at the open end, has a molding depth to diameter ratio of 1.0 or more, and has an inner diameter and a molded depth of The average wall thickness D of the cavity is equal to or slightly larger than the average wall thickness d of the cavity of molded product A.
The hermetically sealed molded product is inserted into the outer molded product B, which is made of thermoplastic plastic or paper with a diameter equal to or larger than 1.5 mm, and the flanges of the inner molded product A and the outer molded product B are connected to each other, or between the lid material and the inner molded product. A sealed packaging method characterized by bonding the flanges of the product A and the outer molded product B to each other and sealing the gap between the two molded products. 2. The sealed packaging method according to claim 1, characterized in that the contents are heated to a temperature of 60°C or higher and 100°C or lower for post-filling. 3. The hermetically sealed packaging method according to claim 1 or 2, wherein the lid material is made of a material with high gas barrier properties. 4. The hermetically sealed packaging method according to claim 1, 2 or 3, wherein the molded product B is made of a material with high gas barrier properties. 5. Affix a label to the outside surface of the sealed molded product or the inside surface of the outside molded product B, or fit a label or paper tube into the gap between the sealed molded product and the outside molded product B, and then glue it at the flange. A sealed packaging method according to claim 1, 2, 3, or 4, characterized in that the gap between both molded products is sealed.