JP2801690B2 - Food packaging container and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for packaging retort foods and the like, and attaches a shrink film having a print on the side surface of the container to a container having a concave shape on the side. And a method for producing the same.

[Prior Art] Conventionally, there have been known food bacteria and the like in a container capable of being heated and cooked while food is kept in the packaged food.

Generally, in the display and sale of food packaging containers at supermarkets and the like, it is important from the viewpoint of sales promotion of the packaged food to print on the side of the container that is most noticeable to consumers.

Normally, these food packaging containers are molded by vacuum molding, air pressure molding, hollow molding and injection molding, but even when manufactured by vacuum molding and pressure molding, it is not necessary to print on the raw material sheet from the beginning. This is not possible because the printed pattern during molding is greatly deformed.

First, a method of attaching a paper label to the side of the container is also known.However, in heat sterilization or heating cooking of these packages, hot water or water is often applied, and printing paper having low water resistance is torn. There is a drawback that it gets wet and impairs cleanliness.

Therefore, as a method of printing on the side of the container after molding,
First, there is a method of printing a curved surface on the side wall of the container, and second, a method of bonding the printed shrink film to the side of the container with an adhesive, heating the film, and fixing the shrink film by the shrink force of the film and the adhesive force of the adhesive. There is.

The first method has a drawback that it is difficult to print on a curved surface of a concave portion in a container having a concave portion on a side surface, and furthermore, lack of heat resistance of a printing ink, and difficulty of multicolor printing due to a printing means. There is a disadvantage that high-quality printing cannot be obtained. The second method has a disadvantage that the adhesive loses its adhesive strength due to heating, and the film is particularly detached from the concave portion during the heating, and also has a disadvantage that the shrink film cannot be brought into close contact with the concave portion.

[Problems to be Solved by the Invention] The present invention provides a food packaging container that has a beautiful printed side surface and can maintain a beautiful printed side surface even when subjected to heat treatment such as heating for heat shrinkage, heat sterilization, or heat cooking. And a method for producing the same.

Means for Solving the Problems In the case of a container having a side surface having a concave portion, the present inventors have proposed a method of manufacturing a container having a printed side surface by using a shrink film with printing. In order to solve the disadvantage that the shrink film rises and does not come into contact with the surface, if the container wall and the shrink film are fused and fixed by ultrasonic welding at the deepest part of the recess before the heat shrink treatment, printing is possible. It has been found that the shrink film is coated in close contact with the entire side surface of the container, and a beautiful heat-resistant printed side surface can be obtained. Based on this finding, the present invention has been completed.

That is, the present invention relates to a food product, which is a plastic container having a concave portion on a side surface, wherein the shrinkable film with print adhered to the side surface is fused and fixed at the deepest portion of the concave portion on the side surface. Wrapping around the side surface of the packaging container and the plastic container having a concave portion on the side surface, a cylindrical printed shrink film having a dimension substantially equal to the height of the side surface and slightly longer than the length of the periphery of the side surface is wound. A food packaging container, wherein the container side wall and the shrinkable film are fused and fixed by an ultrasonic sealer or a high-frequency sealer at the deepest portion of the side recess, and then the shrinkable film is shrunk by heating and fixed to the side surface of the container. Is provided.

The resin used as the material of the container body of the present invention is not particularly limited as long as it is a thermoplastic resin that can withstand the heat shrinkage temperature of the shrink film, for example, polypropylene, polyethylene,
Sheets of polystyrene, polyester, polyamide, polycarbonate, vinyl chloride resin, polyvinylidene chloride, saponified ethylene vinyl acetate copolymer, and the like, and multilayer laminated sheets of these resins can be used.

When a multilayer sheet is used, a laminated sheet having a gas barrier resin layer such as a saponified ethylene-vinyl acetate copolymer or polyvinylidene chloride or a metal film layer such as aluminum as the inner layer can be used.

The resin layer of the container of the present invention or the outermost resin layer in the case of a multilayer sheet needs to be a material that can be fused to the shrinkable film with print used in the manufacturing method of the present invention by an ultrasonic seal or a high-frequency seal.

For that purpose, it is desirable that the shrink film and the container side layer be the same resin.

As the cylindrical shrinkable film with printing used in the production method of the present invention, the same resin as the side surface of the container body, for example, a polypropylene film, a polycarbonate film, a polyester film, a vinyl chloride resin film and the like can be used.

In the production method of the present invention, those films obtained by imparting heat shrinkage to these films by a uniaxial stretching or biaxial stretching process can be used.

In particular, it is effective and desirable to form a cylindrical film by making the stretching direction of the uniaxially stretched film coincide with the circumferential direction in order to remove slack when the film is wound around the container side surface.

The heat shrinkable film used in the manufacturing method of the present invention is printed in advance, and in the present invention, both the method of fixing the printed surface toward the side of the container and the method of fixing the printed surface face up are applied. can do.

It is preferable to use the printed side with the back side because the printing stability, the clean feeling, and the adhesive action of the printing ink to the side of the container can be expected.

The shrink film used in the production method of the present invention is used in a cylindrical shape.

It is convenient for operation to form the cylindrical film into a cylindrical shape before winding it around the container body, but a rectangular shrinkable film piece is wound around the side of the container body to form a cylindrical shape on the container body. You can also. in this case,
By polymerizing both ends of the shrink film piece at the deepest part of the concave portion on the side of the container body, if the polymerized portion is fused together with the container body,
This is convenient because the fusion step can be saved at one time and the fusion portion is hidden in a less conspicuous portion of the concave portion.

The dimensions of the cylindrical shrink film used in the production method of the present invention can be selected according to the dimensions of the container body.

The height of the cylindrical film is generally substantially the same as the height of the side surface of the container body, but a desired height can be selected.

In some cases, it is also preferable to increase the height of the cylindrical shape so that the shrink film extends to the periphery of the bottom of the container body.

The circumferential length of the cylindrical film used in the production method of the present invention,
It can be 102-110% of the maximum circumferential length of the outer surface of the container body.

If this dimension is too short, the operation of fitting a preformed cylindrical film into the container body and the operation of overlapping the rectangular film on the container body become difficult, and if this dimension is too long, the printing will be deformed in the heat shrinking step. .

The shrinkage ratio of the shrink film used in the production method of the present invention is 90
Those having a shrinkage ratio of 5 to 55%, preferably 10 to 50% at a processing temperature of about 120 ° C can be suitably used. When the shrinkage is low, the close contact between the container body and the shrink film becomes insufficient, and the aesthetic appearance of printing is impaired.

If the shrinkable film does not have enough size for the circumference of the container body and the shrinkage ratio is too high, the container body may be deformed.

The container body having a concave portion on the side to which the manufacturing method of the present invention is applied is, for example, a container having a heart-shaped container storage portion as shown in the bottom view of FIG. 1 or a side view of FIG. As described above, there is a gourd-shaped side view, and the present invention is not limited to this. The present invention can be applied to a container having one or two or more concave portions of various shapes on the side in the vertical and horizontal directions.

An example of the manufacturing method of the present invention will be described in more detail with respect to the case of the heart-shaped container shown in FIG.

The heart-shaped container body 10 shown in the bottom view of FIG. 1 and the side view of FIG. 2 has a side height of 22 mm, and the heart shape at the bottom is 62 mm in length between AB in FIG. Length between CDs 48
mm, length between EF is 33mm, length between DF is 58mm
It is. In the storage portion of the upper edge flange portion, the distance between A 'and B' corresponding to AB on the bottom is 67 mm, and other dimensions are increased by this ratio to form a heart shape similar to the bottom.

The outer peripheral length of the side of the container body is just below the flange.
It is 104 mm and 92 mm at the bottom. A flange H is provided on the upper surface of the storage portion for joining with the lid.

The material of this heart-shaped peel-type food container body is thickness
It consists of a three-layer laminated sheet of 0.6 mm polypropylene / saponified ethylene vinyl acetate copolymer / polypropylene,
The three-layer laminated sheet can be vacuum-formed to produce the container body shown in FIGS.

Separately, a rectangular polypropylene film having a thickness of 50μ and a size of 22 × 112 mm, and having a shrinkage of 30% at 100 ° C.
3 is formed into a cylindrical shape as shown in FIG. 3, and the both ends are overlapped by 4 mm, and the overlapped portion 21 is heat-sealed to form a cylindrical film 2 having an outer peripheral length of 108 mm.
0 was produced.

Since the stretching direction of the tubular film 20 is adjusted to the circumferential direction of the tubular shape, the heat shrinkage mainly occurs in the direction in which the circumference is reduced.

The container body shown in FIG. 1 is continuously supplied while being laid down on a conveyor, and the heart-shaped concave portion is mechanically detected and fixed in a certain direction. The shrinkable film is placed on the container body 10 so that the fusion-bonded portion 21 of the shrink film is exactly on the CC 'line of the concave portion.

Then, by ultrasonic waves, the joint 21 of the shrink film and the deepest part CC 'line of the container body are fused, then the container is removed from the ultrasonic sealer, and then introduced into the heating tunnel by a conveyor, The shrinkable film is heated and shrunk by hot air, and the shrinkable film is shrunk to bring the print film into close contact with the container body, whereby the printed packaging container shown in the vertical structure in FIG. 4 can be manufactured.

As described above, the manufacturing method of the present invention winds a shrink film that has been printed in advance on the side surface of the container body having a concave portion on the side surface, using an ultrasonic sealer or a high-frequency sealer at the deepest position of the concave portion, It comprises a first step of fusing the shrink film and the deepest part of the container body, and a second step of heating the shrink film to shrink the shrink film.

The ultrasonic welding or the high-frequency welding used here as a fusing means is most suitable for the manufacturing method of the present invention in that heat shrinkage hardly occurs when applied to a shrink film. In addition, high frequency fusion can be used particularly when a vinyl chloride resin film is used.

In the heat shrinking step, the container is often partially deformed with the shrinking force of the film concentrated at one location, for example, at the joint portion of the film. To avoid this deformation,
On the outer surface of the container body or the inner surface of the shrink film, a heat-sensitive adhesive exhibiting an adhesive strength at about the shrink temperature of the shrink film, for example, about 80 to 100 ° C., for example, rosin, rosin derivative, pinene resin, petroleum resin, When coated with low molecular weight polyolefin, crystal wax, etc., there is no adhesiveness when the cylindrical film is attached to the container body, but the film adheres to the entire surface of the container body during heat shrinkage and contraction contraction force Are dispersed over the entire outer surface, which has the effect of preventing the container from being deformed. In addition, in the case of an ultrasonic seal or a high-frequency seal, even if the adhesive layer is interposed between the resin layers to be fused, this does not hinder the fusion, so that the fusion strength at the deepest portion of the concave portion is reduced. It is convenient in that it is not allowed to do so.

When the printing area of the shrink film is large, printing on the inner surface of the cylindrical shape is convenient because the printing ink layer acts as a heat-sensitive adhesive and plays a role of dispersing the shrinkage and contraction force. In order to promote this effect, a printing ink to which a heat-sensitive adhesive is positively added can be used.

The container of FIG. 4 manufactured in this manner contains food therein, is joined with a lid film on the upper flange portion H, is sealed and packaged, is heat sterilized, and is transported as it is.
Can be sold for display.

As a container having a concave portion on the side to which the present invention can be applied,
As shown in the bottom view in FIG.
It is also applicable to those at locations C2, C3, C4, C5. In this case, there are four deepest portions for each concave portion. At each position, the cylindrical shrink film is fused and fixed to the side of the container from immediately below the flange portion to the bottom surface by an ultrasonic seal. It can be manufactured in the same manner as in the case of the heart-shaped container body of FIG.

Also, in the case of a container body having a concave side surface with a constricted center as shown in the side view of FIG. 6, a shrink film with printing is similarly fused to the circumference of the deepest portion C6 of the concave portion of the central concave portion to produce the present invention. The method can be performed.

Further, as shown in the side view of FIG. 7, two shallow concave portions C7 and C8 are horizontally provided near the upper edge and the lower edge of the side surface of the cylindrical container body.
If a similar fusing step and shrinking step are applied to the deepest portions C7 and C8 of this portion, a very strong printing film can be fixed to the side of the container.

When the manufacturing method of the present invention is applied to a container body having a horizontal concave portion on the side face as shown in FIGS. 6 and 7, the stretching direction of the uniaxially stretched shrink film may be set to the vertical direction, or A shrink film that has been used can also be suitably used.

[Effects of the Invention] The food packaging container of the present invention and the manufacturing method of the present invention have an advantage that clear printing can be applied to the side surface of the container, and the printed film does not peel off even when subjected to heat sterilization or heating cooking. This is advantageous in that a printing surface having hot water resistance can be obtained.

And since the manufacturing method of the present invention can be carried out by a continuous process, the production efficiency is high.

[Brief description of the drawings]

FIG. 1 is an example of a container body to which the manufacturing method of the present invention is applied, FIG. 2 is a side view thereof, FIG. 3 is an example of a shrinkable film with printing used in the manufacturing method of the present invention, and FIG.
FIG. 5 is a cross-sectional view of a heart-shaped container as an example of a food packaging container manufactured by the manufacturing method of the present invention, which is cut along a central target plane passing through the deepest portion of the concave portion. FIG. FIG. 6 is a bottom view of the container body, FIG. 6 is a side view of another container body, and FIG. 7 is a side view of another container body. Reference numerals in the figure are 10; container body, 20; shrinkable film with print, 21; film bonding and fusing portion, H; flange portion, K; container bottom, C; lower end of concave portion deepest portion, C '; concave portion deepest portion Top of, C2
To C8; the deepest part of the recess.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B65B 53/00-53/06 B65C 3/06-3/24 B65D 25 / 34,25 / 36

Claims (3)

(57) [Claims] 1. A food container comprising a plastic container having a concave portion on a side surface, wherein a shrinkable film with print adhered to the side surface is fused and fixed at the deepest portion of the concave portion on the side surface. container. 2. A plastic shrinkable film with a cylindrical shape having a dimension slightly longer than the circumference of the side surface is wound around a side surface of the plastic container having a concave portion on the side surface. Fusing and fixing the side wall and shrink film by ultrasonic sealer or high frequency sealer,
Then, the shrinkable film is shrunk by heating and fixed to the side surface of the container, thereby producing a food packaging container. 3. The method for manufacturing a food packaging container according to claim 1, wherein the shrinkable film is a uniaxially stretched film which is stretched in a circumferential direction of a cylindrical shape.