JPS5814743A - Package - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a package that has good gas barrier properties and can be heat sterilized.

More specifically, the gas barrier is made of a multilayer plastic film with a single-layer structure, including a polyamide resin layer as the outermost layer, a modified polyolefin adhesive resin layer, a saponified ethylene-vinyl acetate copolymer resin layer, a heat seal resin layer, etc. -After the food contents are degassed and packaged using a heat-shrinkable multilayer film with good properties such as flexibility, heat resistance, and transparency,
The present invention relates to a package that is heat sterilized for more than 5 minutes in an atmosphere of 100°C to 100°C.

In recent years, in the food processing industry, particularly in the meat processing and fish processing fields, regulations on food additives have become stricter, and the use of disinfectant needles has been reduced or almost no longer used. In order to ensure long-term shelf life and freshness, packaging that has good oxygen gas barrier properties and can be heat sterilized is required.On the other hand, from the sales promotion aspect of market development, packaging that has excellent transparency and wrinkle-free packaging is required. There is a demand for a package with a good appearance, and the present invention is a package that satisfies these demands.

Conventionally, for packaging of processed meat products such as hams and sausages, laminated heat-shrinkable films of ethylene-vinyl acetate copolymer resin and vinylidene chloride resin, or combinations of polypropylene resin, polyamide resin, polyethylene resin, etc. have been used. Achievements J-film etc. were used.

However, although packaging bodies using vinylidene chloride-based laminated heat-shrinkable films have excellent oxygen gas barrier properties, after deaerating the food contents and sterilizing them by heating for 5 minutes in hot water at a leap temperature, However, there are also disadvantages in that pinholes sometimes occur in the package and peeling occurs in the film.

4. Packaging bodies using a laminated film of lipropylene resin and polyethylene resin or a laminated film of polyamide resin and polyethylene resin should be packaged in boiling water at a temperature of 100°C to 100°C for 60 minutes after deaerating the food contents. Although it is possible to withstand heat sterilization, the oxygen gas barrier properties are affected, and the edible shelf life of the processed meat or fish meat products is short, and at the same time, the Danj-film is not heat-shrinkable. However, after heat sterilization, folds and wrinkles appear on the package, which deteriorates its appearance.

In this way, the oxygen gas barrier property is good.
It satisfies all drinking performance requirements, such as being able to be heat sterilized for more than 5 minutes in an atmosphere of 100°C, and adding heat-shrinkability to the glass film in order to obtain a package with a good appearance and no folds or wrinkles. The packaging could not be found.

The present inventor has developed an ethylene-vinyl acetate copolymer resin with excellent oxygen gas barrier properties that is stable over a long period of time, has a gas barrier property of 9 sieveness, and exhibits high heat shrinkage in hot water. In order to obtain a package that can be heat sterilized for a long period of time, research was carried out with a polyamide resin layer as the outermost layer, a modified polyolefin adhesive resin 1-, and a saponified ethylene-vinyl acetate copolymer resin layer. and heat seal resin I-
A multilayer plastic sheet with a laminated structure including
These heat-shrinkable multilayer plastic films can be biaxially stretched at a temperature below ℃, and after deaerating food contents and packaging them, they can be stretched for 5 minutes in an atmosphere between leap ℃ and 100℃. The inventors discovered that heat sterilization that exceeds the limit of heat sterilization was possible, and after conducting various studies, they were able to develop the present invention.

The purpose of the present invention is to ensure that the food contents, after being degassed and packaged,
It can withstand heat sterilization for more than 5 minutes in an atmosphere of 100°C to 100°C, has stable oxygen gas barrier properties and moisture proof properties over a long period of time, and has excellent low-temperature heat absorption properties, transparency, hygiene, etc. An object of the present invention is to provide a packaging body using an excellent heat-shrinkable multilayer plastic film for food packaging.

The present invention comprises a polyamide resin 1 m (A) as the outermost layer, a modified polyolefin adhesive resin layer ψ), a saponified ethylene-vinyl acetate copolymer resin layer (0), a heat seal resin wj (D), etc. For example, a multilayer plastic film having a laminated structure including (A) - (B) - (0) - (B
) −(D) or (A) −(0) −(B) −(
D) or (A) -(0) -(A)-(B) -(
D) Or a multilayer plastic film with a laminated structure in which (A) - (C) - (B) are adjacent in the order, and the total thickness of the film is IO μm to 2C1 (1 μm, 10
The contents were degassed and packaged using a heat-shrinkable multilayer film that had a dimensional shrinkage of more than 10% in both length and width after 10 seconds of being placed in an atmosphere at a temperature of 0°C, and then heated to 80°C. This package is characterized by being heat sterilized for more than 5 minutes in an atmosphere of more than 5 minutes.

Polyamide Jugetsuji is W-Aminocal? It is produced by the polycondensation reaction of phosphoric acid or the polycondensation reaction of dibasic acid and cyanide, such as 6-nylon, 6-6 nylon, 610-nylon,
These include 11-nylon, 12-nylon, and copolymers thereof, and particularly preferred is a copolymer polyamide resin of C-caglolactam and hexamethylene diammonium anopate.

The modified polyolefin adhesive resin is modified polypropylene resin, modified polyethylene resin, or modified ethylene resin in which a polar group such as unsaturated carboxylic acid is graft copolymerized.
i! r1': An acid vinyl copolymer resin, a blend thereof, or an ionomer resin copolymerized with a comonomer, etc. Among these, a modified ethylene-vinyl acetate copolymer adhesive resin has particularly good adhesive performance. The modified polypropylene adhesive resin has good heat resistance and is therefore preferable.

Ethylene-vinyl acetate copolymer saponified resin has a softening m
& (flow tester method) at 150°C to 175°C,
The ethylene content is 5 to 75 moles, the degree of saponification of vinyl acetate in the co-monomer is 90% or more, and it has extremely high oxygen gas barrier properties in a dry state.

What about heat seal resin? It is a lyolefin-based resin, and includes low-density polyethylene resin, medium-density polyethylene resin, high-density polyethylene resin, ethylene-vinyl acetate copolymer resin, polypropylene resin, ionomer resin, and copolymers of each resin. 1mM or a blend thereof.

The total thickness of the plastic film used in the present invention is 1
( ) μm to 0.102 m, and glass films with a thickness within this range are suitable for shrink packaging of foods.

The present invention is aimed at shrink packaging and heat sterilization packaging for food products, so items to be packaged, such as processed meat products, are filled into a bag made of a heat-shrinkable multilayer film, and after the inside is deaerated, the mouth part is Heat-seal and heat sterilize at the same time as shrink-wrapping by heating at 10°C to 10°C for more than 5 minutes.

When food products are packaged in a heat-shrinkable multi-layer film and the inside is degassed, the food products are heated, the poly 1m film shrinks, the food products and the multilayer film come into close contact, and the multilayer film folds. A wrinkle-free package with a good appearance can be obtained, and at the same time, the package with this appearance can be heat sterilized.

The heat-shrinkable multilayer film for this purpose must be heated to at least 100°C.
It must have a dimensional shrinkage of more than 10 inches in length and width after 10 seconds after being placed in an atmosphere at a temperature of
Peeling of the heat-sealed portion does not occur.

The degassing packaging method for food products is carried out using a single method or multiple methods, in which the food contents are filled into a bag-shaped bag made of a heat-shrinkable multilayer film, and the food is packed at a degassing pressure of 760 tung Hf. After the inside of the bag is degassed, the opening is heat-sealed.

The method for producing the heat-shrinkable multilayer film used in the present invention is as follows:
A multilayer plastic sheet having a laminated structure including an outer layer of Ilyamide resin, a modified polyolefin adhesive resin layer, a saponified ethylene-vinyl acetate composite resin layer, a heat-sealing resin JWI, etc. The lO-Tsuku sheet is produced by bath-melt extrusion from a laminated gou using a co-extrusion method using multiple extruders, cooled and solidified, and then
The film is characterized in that it is reheated to a cross-concave circle stretching temperature of 100°C to 100°C, biaxially stretched by 1.5 times or more in the machine direction and 1.5 times or more in the transverse direction, and then cooled.

It is essential to have a polyamide resin layer as the outermost layer for packaging food contents in the laminated structure of the multilayer glass sheet before stretching. Either extrusion or flat extrusion through a T-die is preferred.

Next, this tubular sheet or flat sheet is reheated to a concave circular stretching temperature of 70° C. to 100° C., and subjected to simultaneous biaxial stretching or longitudinal stretching using a known tubular method or tenter method. By sequentially performing biaxial stretching, a film with good appearance can be produced.

After deaerating and packaging processed meat products with the heat-shrinkable multilayer film of the present invention using the above-mentioned manufacturing method,
After heat sterilization, the package was immersed in boiling water at 0℃ for 60 minutes.
The processed meat products can be stored for a long period of time without any abnormalities such as creases, damage to the packaging, etc., which would otherwise deteriorate the appearance.

The main effect of the package of the present invention is that polyamide resin and saponified ethylene-vinyl acetate copolymer resin, which are extremely difficult to be biaxially stretched at temperatures below 100°C, are heat-sealed via a bonding resin. The multilayer structure made it possible to biaxially stretch the polyamide resin layer and the saponified ethylene-vinyl acetate copolymer 4# resin layer at a temperature of 100°C or less. Since the outermost resin layer is made of a heat-shrinkable multilayer film, the contents can be deaerated and packaged at 80°C.
It has been discovered that heat sterilization for more than 5 minutes is possible in an atmosphere of 100°C to 100°C.

The stretching ratio of biaxial stretching is 1.5 times or more in both length and width,
Preferably it is 2 to 4 times. In order for the dimensional shrinkage rate to exceed 10% in both length and width after 10 seconds of being placed in a 100°C atmosphere, it is necessary to stretch the film by a factor of 1.5 or more in each direction.

Dimensional shrinkage rate (α) is the length of the original film t. , if the film is placed in an atmosphere at a constant temperature and the length of the film after a certain time is t, α = 100・(to-t)/Lo (
%).

The heat-shrinkable multilayer film of the present invention has a dimensional shrinkage rate of 20% to 5% after 10 seconds when placed in an atmosphere of 70°C to 100°C.
Preferably, it is 0%.

In order to obtain such a film, it is preferable to carry out biaxial stretching of 2 to 4 times in both length and width at a temperature of 70°C to (3)°C.

Next, examples of the present invention will be described.

Table 1 shows examples of the present invention.

13- Where PA: Copolymerized polyamide resin of εcaglolactam and hexamethylene diammonium adipate (melting point 190°C) E! VA-OH: Ethylene-vinyl acetate copolymer saponified resin (softening temperature 170°C) [Change] II! VA: Modified ethylene-vinyl acetate copolymer adhesive resin Modified PP: Modified, ie IJ dipropylene adhesive resin Modified PE: Modified polyethylene adhesive resin EVA: Ethylene-vinyl acetate copolymer resin (vinyl acetate content 8% by weight) ) PE: Low-density polyethylene resin (melting point 1()5°C) PP: Ethylene-propylene random copolymer polypropylene resin (softening temperature 140°C) Iono? : Ethylene-methacrylic acid co-15-14-polymer (melting point: 99°C).

The raw sheets of the films of the N[Ll to Nα7 examples shown in Table 1 were all produced by the T-die coextrusion method, and melt-extruded from a multilayer die to produce sheets with a thickness of 20011 m. .

Next, after reheating the sheet using a biaxial stretching device,
A film with a thickness of about 5 olIm was made by stretching it twice in both the length and width, and the film was then stretched to twice the length in both the length and width.
Package heating testability, etc. were evaluated.

The appearance of the film is good if it has good transparency, smoothness, and no stretching unevenness, and there is no stretching unevenness due to binding. Those with poor smoothness and transparency were judged as defective.

The thickness of each layer of the film is determined by the order of composition and the order of thickness composition.
They are shown correspondingly from left to right.

Heat shrinkability is considered good if the film is placed in boiling water, taken out after 10 seconds and cooled, and exhibits a dimensional shrinkage of more than 10% in both length and width before and after boiling.
Anything less than that was considered defective.

Oxygen gas barrier properties are determined using test method ASTM-D-143.
4, measured in a dry state at 20°C, and 30
”/M2-24 hr, A-TM or less, the oxygen gas barrier property is good.

The package heating test property was determined by heating each of the above-mentioned films at a length of 13 cm.
Processed into a bag shape with a three-sided seal of 1;3an in width, the bag was filled with grilled pork, which is an irregularly shaped hole-processed product with a protrusion of about 2002 mm, as food content, and 760+
After degassing the terminal at a degassing pressure of mnH1', the opening is heat-sealed in the deaerated state.

As a sealing method, a hot plate sealer heated to 130° C. is used, and sealing is performed with a hot plate pressure of 2 odor/−1 and a heating time of 1 second.

The thus obtained package is closed and heated in hot water at 100°C for 5 minutes or at the same time as shrink wrapping for printing, and the number of samples is 10 at the same test level.

After heating, a sample with no degassing leak due to a broken seal or a pinhole is considered good, and a sample with even 1 out of 10 degassing leaks is considered bad.

In the comprehensive evaluation of the package, a film that is good in all of the film appearance, heat shrinkability, oxygen gas barrier properties, and package heat test properties is rated as good (marked O) and L7, and those that are defective in any of them are rated as poor ( (x mark).

In Table 1, the polyamide resin is nylon manufactured by Ube Suichi with a melting point of 190°C, and the saponified ethylene-vinyl acetate copolymer resin has a softening temperature (flow tester method).
Everlu C% manufactured by Kuraray at 170℃, modified ethylene-vinyl acetate copolymer adhesive resin, modified propylene adhesive resin, and modified polyethylene adhesive resin are:
The ethylene-vinyl acetate copolymer resin is Evatate (vinyl acetate content LjftM%) manufactured by Sumitomo Chemical, and the low-density polyethylene resin is manufactured by Sumitomo Chemical with a melting point of 105°C. The polyzolopylene resin is an ethylene-propylene random comonomer polypropylene resin manufactured by Sumitomo Chemical with a softening temperature of 140°C, and the ionomer resin is an ethylene-methacrylic random comonomer polypropylene resin with a melting point of 99°C with Zn ions added. The treated resin is Himiran manufactured by Sankatabori Chemical ■.

As is clear from Examples αI to 816, the packaging of the present invention has excellent transparency, a packaging appearance free from folds and wrinkles due to low-temperature heat shrinkability, and extremely good oxygen gas barrier properties.
Moreover, the package can be heated for 5 minutes to ω minutes in an atmosphere of 5°C to 100°C.

As is clear from floors 7 to 8 of the example, it was found that the package containing the outermost R4K ethylene-acetyl vinyl copolymer saponified resin layer did not withstand the package heating test. ! - A package containing an unstretched polypropylene resin layer can withstand the package heat test, but has no heat shrinkage and is resistant to oxygen gas.

It was found that these packages were poor in appearance, low-temperature heat shrinkability, oxygen gas barrier properties, package heating test performance for more than 5 minutes in an atmosphere of closed temperature to 100℃, etc. It is not possible to create a package that satisfies all of the following.

Patent applicant: Sumitomo Bakelite Co., Ltd.-2)-

Claims (6)

[Claims] (1) Modify the polyamide resin layer (A) as the outermost layer? It is a multi-plastic film with a laminated structure including diolefin adhesive resin) fil (B), saponified ethylene-vinyl acetate copolymer 11 fat layer (0), heat seal resin layer (B), etc. of#! 83 has a thickness of 10 μm to 200 μm, is placed in an atmosphere at a temperature of 100°C, and the contents are degassed and packaged with a heat-shrinkable film with a dimensional shrinkage rate of over 10 inches in both length and width, and heated to 80°C.
A package characterized in that it is heat sterilized for more than 5 minutes in an atmosphere exceeding 5 minutes. (2) A multilayer plastic film with a laminated structure is formed from the outermost layer (A) - (B) - (0) - (B) - ■) or (
A) -(0) -(B)-medium) or (A)
-(0) -(A) -(B)-Φ) or (A)
The package according to claim (1), which has a laminated structure in which the following layers are arranged adjacent to each other in the order of -(Cri) and -(B). (3)/Lyamide resin/il (A) is a copolyamide resin layer, Claims (1) to (2)
) Packaging described in section 2. (4) The modified polyolefin adhesive resin layer Φ) is made of modified polypropylene resin, modified polyethylene 118rtl, or modified ethylene-
The package according to claims (1) to (3), which is a vinyl acetate copolymer resin, a blend thereof, or an ionomer resin obtained by co-merging comonomers. (5) The saponified ethylene-vinyl acetate copolymer resin layer (0) is a resin having an ethylene content of 5 to 75 moles and a degree of saponification of vinyl acetate in the copolymer of 9 degrees or more. The package described in items (1) to (4). (6) The heat-sealing resin layer CD) is a chiliethylene resin, an ionomer resin, an ethylene-vinyl-in-acetate copolymer resin, a polyg-pyrene resin produced by Shishisha Co., Ltd., or a blend of these resins (Claim 1) The package described in items (5) to (5) above.