JPH02248244A - Heat-shrinkable sealing lid material - Google Patents

Abstract

PURPOSE:To obtain the title material generating no slackening and wrinkles due to heat sealing, in a lid material for a multilayer packing container consisting of an aluminum foil, a synthetic resin film and a heat-sealing layer, by laminating a heat-shrinkable film to the outside of the aluminum foil. CONSTITUTION:In a lid material for a multilayer packing container consisting of an aluminum foil, a synthetic resin film and a heat-sealing layer, a heat- shrinkable film is laminated to the outside of the aluminum foil to obtain a heat-shrinkable heat-sealing lid material. As the heat-shrinkable film, a biaxially stretched film composed of a synthetic resin having a relatively high m.p. such as polyester, polyamide or polypropylene is pref. and the thickness thereof is 9-50mum and pref. occupies 10-50% the thickness of the lid material. Further, this heat-sealing lid material is advantageous because it generates no slackening and wrinkles not only by heat sealing but also by boiling sterilization or retort sterilization.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to MRQ-shaped heat-sealed stone materials, particularly glass bottles, Plus Deck containers, aluminum foil containers, etc., filled with beverages or foods, heat-sealed, and then retort sterilized. The present invention also relates to an improved heat sealing material for colored containers that require heat treatment such as boiling sterilization.

[Conventional technology J] With the development of synthetic resins in recent years, many heat-sealing materials have been developed and have been incorporated into the field of automatic packaging for beverages, foods, etc., and this technology has made significant progress, and has also been used to protect the contents from acid oxidation. In order to reduce the number of arms as much as possible, many proposals have been made to laminate aluminum foil on the synthetic resin layer. Using these techniques, we can produce milk, milk, juice, etc., jams, jelly, dried substances such as water yolk, powders such as instant coffee and powdered milk, and boiled foods such as fish and beef. (Previously canned)
Large quantities of packaged products such as these are shipped to the market and displayed on the shelves of supermarkets, food stores, and other stores.

These packaged products have beautiful printing on the packaging itself, attracting housewives and others to purchase them.

[Problem to be solved by the inventionffi] As mentioned above, some of the packaged products for beverages and foods are filled into containers, heat-sealed with a heat-sealing lid material, and then further subjected to boil sterilization, retort sterilization, etc. There are many food packaging products that require heat treatment.

If these containers are narrow bottles and the area of the lid material is small, they will be less noticeable and there will be fewer problems. Or plastic [Shallow bottom like H-packed and open 1
In the case of plastic containers (with large corners), wrinkles tend to form due to expansion of the lid material when it is heat-sealed.

Furthermore, even if heat sealing is successful and wrinkle-free, 1M material is prone to walnuts and wrinkles due to swelling due to internal pressure during subsequent boil sterilization or retort sterilization and contraction due to subsequent cooling.

These walnuts and wrinkles are often seen near the heat-sealed part (around the neck of the container), and the middle part of the lid has a convex shape.

Such walnuts and wrinkles on the Oto part not only make it difficult to read the letters and designs printed on the Otsu part (but also significantly reduce the commercial value of the product, and there is even a risk that the quality of the contents has deteriorated). be.

The inventors of the present invention conducted research to solve the above-mentioned problems regarding heat-sealed lids that do not produce walnuts or wrinkles not only by heat sealing but also by boiling sterilization and retort sterilization.

[One Step to Solve the Problems] The present invention provides a lid material for a multilayer packaging container composed of a small amount of aluminum foil, a synthetic resin film, and a heat-sealing layer, in which a heat-shrinkable film is provided on the outside of the aluminum foil. The above problem was solved by developing a heat-shrinkable sealing material made by laminating the following materials.

That is, the aluminum foil used in the present invention is intended to provide rLa elementary barrier properties, and may be one or more than one sheet. Furthermore, a thin film such as a vapor-deposited film thinner than foil can also be used if it has sufficient '1liI elemental barrier properties.

As the synthetic resin film, 1. Synthetic resin films normally used for packaging materials can be used, including high-density or low-density polyethylene (including linear low-density polyethylene),
Bolib [1-pyrene, polyvinyl chloride, polyvinyl alcohol, polyvinylidene chloride, etc. are selected from the viewpoint of price, properties, etc.

These layers are laminated by coextrusion lamination, dry lamination, or the like. In the case of the S+ layer, brimer treatment, plasma treatment, etc. may be performed.

When a certain degree of rigidity is required as a lid material, paper or the like may be used and laminated.

The heat-sealing layer must be selected depending on the processing temperature of boil sterilization, retort sterilization, etc., but ordinary heat-sealing compositions such as low-density or high-density polyethylene, ethylene-vinyl acetate resin, modified polyethylene (polypropylene), etc. can be used. . This is laminated to the adhesive surface with the container.

The heat-shrinkable film used for the lid material to prevent walnuts and wrinkles is biaxially stretched polynisdel.

A synthetic resin film having a relatively high melting point such as polyamide (polypropylene) is preferred.

The shrinkage of these materials must be selected depending on whether the material is for boil sterilization or retort sterilization at 100° C. or higher, but a smaller shrinkage rate tends to be better in cases where high-temperature processing is required.

That is, 1.2-5% by heating at 80°C for 5 minutes. 90℃
A film that shrinks by about 1.7 to 7% when heated at 100°C for 5 minutes or 3 to 10% when heated at 100°C for 5 minutes is good.

Hot water shrinkage rate of normal two-wheel stretched nylon film (100
℃ x 5 minutes) is 1.0 to 360%, and since the value of the present invention is smaller than 3 to 10%, a sufficient effect cannot be expected.On the other hand, 10! If the shrinkage rate is greater than +6, the shrinkage is too large, which may cause peeling from other laminated materials or weaken heat sealing, which is not preferable.

It is easy to use a heat-shrinkable film with a thickness of 9 to 50 μm according to the Agency. If it is thinner than 9 μm, lamination is difficult, and if multiple sheets are used, the shrinkage force is weak, so walnuts and wrinkles will disappear sufficiently. tend to lack power.

On the other hand, if it is less than 501 Lm, there is no commercially available product and it is a custom-made product, which is not only expensive, but also the shrinkage force becomes large even if the shrinkage rate is small, causing distortion to other parts, so it is better to avoid it.

This heat-shrinkable film is 10 to 10 times the thickness of the entire stone.
If the overall thickness and the thickness of the heat-shrinkable film are selected to be 50%, a heat-shrinkable sealing material that is resistant to walnuts and wrinkles can be obtained.

Note that the heat-shrinkable film is not very effective when placed on the inside of the aluminum foil (the surface that adheres to the container), causing walnuts and wrinkles on the lid, so it is necessary to laminate it on the outside. Although it is desirable to print directly on this heat-shrinkable film, a printed film may be laminated thereon.

Packaged products heat-sealed using the lidding material of the present invention are subjected to boil sterilization or retort sterilization to shrink the heat-shrinkable film and leave the lid in a stretched state to eliminate walnuts and wrinkles on the lid. It became possible to increase the product value.

[Example J] The present invention will be described in detail with reference to Examples below, but the present invention is not limited thereto.

(Actual 1Ml @ It) 9 coats of 1/tan adhesive on both sides of 9ILm aluminum foil, 151Lm of 6 nylon stretched on one side with two wheels (shrinkage rate 10 (1”CX 5 minutes, 360%) of,
One side is laminated with high-density polyethylene with MIl, 0.
It was made into a heat-shrinkable sealing material.

This lid material was coated with MFr2. It was heat-sealed to a container (contains water) in which polypropylene of Fi and high-density polyethylene of 10 μm, Mll, 0 were laminated. 100 of these packages were sterilized by boiling for 15 minutes and the appearance of wrinkles and walnuts on the lids was examined, and all were found to be tightly packed.

(Example 2) Biaxially oriented polynisdel (12μm)/Adhesive/Biaxially oriented nylon (15μm)/Adhesive/Aluminum foil (9μm)
rn)/adhesive/edylene-vinyl acetate copolymer (50
μm) (however, the shrinkage rate is 100°C x 5 minutes, 1.0% for polyester, 2.0% for nylon) in a polypropylene container filled with water, and heated to 11.5°C.
Retort sterilization was performed. As a result, there were no wrinkles or walnuts.

(Comparative example) Polyethylene (20μm)/aluminum foil (9rzm
)/adhesive/6-nylon (15 urn)/adhesive/ethylene-vinyl acetate copolymer (2511 m) laminate was treated in the same manner as in Example 2. As a result, out of 100 packages, there was no damage to the heat seal, but walnuts were observed in the periphery of the lid in 2 packages, and in 1 package, wrinkles were observed in the heat seal area. .

[Effect J] The present invention is an improved heat-sealing lid material for packaging containers that requires retort sterilization or boil sterilization and is made of at least an aluminum foil, a synthetic resin film, and a heat-sealing layer. This prevents the occurrence of walnuts and wrinkles on the lid, which can be a problem when packaging products.As a result, it is possible to prevent the reduction in product value due to distortion and wrinkles of the packaged product, and the lid surface is kept smooth, making it easier to print. We were able to provide a heat-shrinkable 1.1 lid material that can fully exhibit the following effects.

Patent applicant Showa Aluminum Co., Ltd. Agent
Patent Attorney Seki Kikuchi

Claims (3)

[Claims] (1) In a multilayer lid material for a packaging container composed of at least aluminum foil, a synthetic resin film, and a heat-sealing layer, a heat-shrinkable film is laminated on the outside of the aluminum foil (on the opposite side of the heat-sealing part). A heat-shrinkable sealing lid material characterized by: (2) The heat-shrinkable sealing lid material according to claim 1, wherein the heat-shrinkable film has a thickness of 9 to 50 μm and accounts for 10 to 50% of the thickness of the lid material. (3) The total shrinkage rate of the heat-shrinkable film is 1.2 to 5% in the machine direction and the direction perpendicular thereto when heated at 80°C for 5 minutes, and 1.2% when heated at 90°C for 5 minutes.
The heat-shrinkable sealing lid material according to claim 1, which is a heat-shrinkable film having a density of 7 to 7%, or 3 to 10% by heating at 100°C for 5 minutes.