JPS6028612Y2 - Composite film for lid material - Google Patents

Description

[Detailed description of the invention] The present invention relates to a composite film for lid material used in deep drawing packaging, and more specifically, a composite film for lid material for providing a packaging body characterized by less curling. It is related to.

A packaging form called deep-draw packaging is generally used for meat packaging such as hams and sausages, but the current problem with this deep-draw packaging is that the main body of the package is formed after being sterilized by boiling in hot water. This means curling it to the side.

Note that boiling sterilization is performed to extend the shelf life of the contents of ham, etc.

For this reason, the present inventors conducted various studies to see if it would be possible to create a package with less curling after foil sterilization by sealing a lid material with a main layer of polyamide resin on the main body of the molded phase that houses the contents such as ham. It has been found that if the composite film according to the present invention is used as a lid material, it is possible to obtain a package with very little curl after boiling sterilization, in other words, a package that is prevented from curling.

As a result of investigating the cause of curling in the packaging after boiling sterilization, it was found that it is caused by a difference in the degree of shrinkage between the main body and the lid material, and curling generally occurs on the side of the main body that is being molded. Therefore, this curling can be prevented or reduced by increasing the shrinkage rate of the lid material and reducing the unbalance of shrinkage between the main body side and the lid material.

In other words, the idea was to prevent the package from curling by increasing the shrinkage of the lid material, which tends to curl toward the main body, so that it curls in the opposite direction of the lid falling over.

Therefore, the inventors of the present invention have discovered that by using a stretched polyamide resin used for the lid material, the shrinkage rate of the lid material increases, and the scales prevent the package from curling during boil sterilization.

To explain the present invention through examples, Fig. 1 shows an example of the bark of the main body film, and the structure is as follows: the outer layer 1 is made of polyvinylidene chloride coated polyamide resin (hereinafter referred to as KNy), or the polyolefin film sealing layer 2 is made of It consists of a composite film laminated with a sealing resin film such as ionomer paper film (hereinafter referred to as ionomer).

Fig. 2 shows an example of a conventional composite film for lid material, in which the outer layer 3 is made of polyamide resin, such as nylon 6 or an unstretched nylon film (hereinafter referred to as A group nylon) made of nylon 6, and the middle layer 4 is a polyvinylidene chloride coated cellophane (hereinafter referred to as KM) film, and the sealing layer 2 is made of an ionomer, an ethylene vinyl acetate copolymer (hereinafter referred to as EVA) or a polyethylene (hereinafter referred to as PE) film.

Fig. 3 shows an example of the structure of the composite film for lid material according to the present invention.As for its structure, the outer layer 5 is a stretched nylon film (hereinafter referred to as B group nylon), the middle layer 4
is KM, seal layer 2 is ionomer, EVA is PE
It's a film.

Looking at the difference between Figures 2 and 3, Figure 4 graphically represents the shrinkage rate of each group of nylon used in the film composition, and the shrinkage rate for each group of nylon used in the film composition is shown in Figure 4. Looking at the shrinkage rates before and after °C, the order is that of group (B) and (4) nylon, and group (B), that is, stretched nylon film, has the largest shrinkage and is not effective as a composite for the curl-preventing lid material of the present invention. You can say it's big.

Next, the main body was molded by pressure molding, filled with ham, and the film structure using nylon of each group, that is, the film of the structure shown in FIG.

FIG. 5 shows the results.

As you can see, before boiling, the body side curls to some extent no matter which type of nylon is used, and there is no particular difference between the three types, but after boiling sterilization with hot water at 90℃ As seen in Figure 5 of the new construction, nylon 6,
In the case of a composite film package in which the surface layer of the cover material is made of ordinary unstretched nylon (Nylon 6), that is, group A nylon, the curling becomes even worse and the product has almost no value, but the stretched nylon film of the present invention Regarding Group B, the shrinkage rate of the type of nylon used was greater than that of the main body, so a curling force was exerted to topple the lid, resulting in a package with less curling, as shown in Figure 5.

In this way, in the case of a package using the lid composite film of the present invention, a package without curling can be obtained after boiling sterilization, so it is an optimal packaging form for food products such as hams and sausages that require boiling sterilization. can be provided.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of the film of the main body, and Fig. 2 is a structural diagram of a conventional composite film for lid material. Figure 3 is a structural diagram of the composite film for lid material of the present invention. Figure 4 is a schematic diagram of the relationship between temperature and shrinkage rate of nylon by group. FIG. 5 is a diagram showing the state of curling before and after boiling and sterilization of packages using composite films for lid materials of various configurations.

Claims (1)

[Scope of utility model registration request] For a lid material characterized by having little curl, the outer layer is a stretched polyamide resin film, the middle layer is a polyvinylidene chloride coated cellophane film, and the sealing layer is an ionomer resin film, an ethylene vinyl acetate copolymer resin film, or a polyethylene film. composite film.