JPH1179191A - Retort-sterilizable packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To support both impact resistance and easiness in unsealing in a packaging bag made of a laminate film comprising a base material layer, an intermediate layer and a sealant layer which are sequentially laminated by using a non-oriented polypropylene film comprising ethylene.propylene.block copolymer resin in the sealant layer. SOLUTION: As a base material layer 11, an oriented or non-oriented film or the like of polyethylene terephthalate, polyvinyl chloride, ethylene.vinyl alcohol copolymer or the like is used. As an intermediate layer 12 between the base material layer 11 and a sealant layer 13, to obtain gas barrier property, an aluminum foil Al or a plastic film or the like with inorganic oxide such as silicon oxide evaporated on a biaxially oriented polyethylene terephthalate film or the like is used. On the other hand, the sealant layer 13 is a resin layer having heat-sealability, wherein it is formed to obtain resistance to hot water to enable retort sterilization by using a non-oriented polypropylene film comprising ethylene.propylene.block copolymer resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retort-sterilizable packaging bag, and more particularly to a retort-sterilizable packaging bag which is excellent in opening property and impact resistance and can be manufactured at low cost.

[0002]

2. Description of the Related Art A retort sterilizing bag for filling curry, porridge, etc., must have sufficient impact strength. When the thickness of the sealant layer is increased to increase the impact strength, when the bag is torn when opened, the film of the sealant layer stretches and it is difficult to open, and the appearance is not good, and both impact resistance and easy opening It was difficult to do.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems relating to retort sterilizable packaging bags, and has a retort having both impact resistance and easy opening properties. It is an object to provide a sterilizable packaging bag.

[0004]

Means for Solving the Problems A first invention of the present invention is:
A retort-sterilizable packaging bag comprising a laminated film in which a base material layer, an intermediate layer, and a sealant layer are sequentially laminated, wherein the sealant layer includes an unstretched polypropylene film composed of an ethylene / propylene / block copolymer resin. It is a packaging bag which can be used for retort sterilization.

According to a second aspect, in the first aspect, the ethylene content of the crystalline polymer component constituting the ethylene-propylene-block copolymer resin is 5% by weight or more, and the rubber component Ethylene content of 4
A retort-sterilizable packaging bag characterized by being at least 0% by weight.

In a third aspect, the present invention provides the first and second aspects, wherein the unstretched polypropylene film has a D
A retort sterilizable packaging bag having a melting peak temperature of 140 ° C. or higher according to the SC method (differential scanning calorimetry). The DSC method is based on JIS K71
21 This is a differential scanning calorimetry method defined in “Method for Measuring Transition Temperature of Plastics”.

As described above, according to the present invention, since a non-stretched polypropylene film composed of an ethylene / propylene / block copolymer resin is used for the sealant layer, retort sterilization excellent in openability and impact resistance is achieved. A possible packaging bag is made. In particular, by setting the ethylene content of the crystalline polymer component constituting the block polypropylene to 5% by weight or more and the ethylene content of the rubber component to 40% by weight or more, it is excellent in opening property and impact resistance, and inexpensive. A retort sterilizable packaging bag is made.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory sectional view showing an example of a layer structure of a laminated film used for a retort sterilizable packaging bag of the present invention.

In FIG. 1, reference numeral 11 denotes a base material layer;
Denotes an intermediate layer, and 13 denotes a sealant layer.

The base material layer 11 may be a stretched or unstretched film of polyethylene terephthalate, polypropylene, nylon, polyvinyl chloride, ethylene / vinyl alcohol copolymer, or a film obtained by applying a vinylidene chloride resin to such a film. Can be preferably used. Further, a printing layer (not shown) may be provided on the side of the base material layer 11 which is in contact with an intermediate layer described later, if necessary.
Furthermore, in order to improve the ease of opening, the plastic film constituting the base material layer is perforated or scratched, or the plastic film is excellently tearable MXD6 nylon, uniaxially stretched nylon, uniaxially stretched polyethylene, Films such as uniaxially stretched polypropylene may be laminated and used.

The intermediate layer 12 is located between the base material layer and the sealant layer and has a role of improving gas barrier properties. The intermediate layer 12 is made of an inorganic oxide such as aluminum foil (Al), silicon oxide, aluminum oxide or magnesium oxide. An inorganic compound deposited plastic film deposited on a plastic film such as an axially stretched polyethylene terephthalate film (PET) or a biaxially stretched polypropylene film (OPP) can be preferably used. Further, a multilayer structure in which the above-mentioned plastic film, paper or the like is appropriately combined with aluminum foil to form a composite may be used.

The sealant layer 13 must be a resin layer having heat sealing properties, and also needs hot water that can be sterilized by retort. The inventors have found that a non-stretched polypropylene film (CPP) composed of an ethylene / propylene / block copolymer resin can be used as a sealant layer satisfying the above conditions. Among them, an ethylene-propylene-block copolymer resin in which the crystalline polymer component constituting the block polypropylene has an ethylene content of 5% by weight or more and the rubber component has an ethylene content of 40% by weight or more. CPP having a melting point of 140 ° C. or higher in DSC can be suitably used.

The bonding of the base material layer 11 and the intermediate layer 12 or the bonding of the intermediate layer 12 and the sealant layer 13 can be performed by, for example, a known dry lamination method using a polyurethane adhesive. Using the thus obtained laminated film, a packaging bag 20 was formed using a generally used thermocompression-type bag making machine such that the sealant layer 13 was on the inner surface (see FIG. 2). The type of packaging bag may be a three-sided sealing bag, a four-sided sealing bag, a pillow packaging bag, a gasket sealing bag, a standing pouch, or any other packaging bag.

[0014]

The present invention will be specifically described below with reference to examples.
The present invention is not limited to the following. <Example 1> First, a P having a thickness of 12 μm,
ET and 7 μm thick Al as the intermediate layer 12 were dry-laminated using a polyurethane adhesive to form a composite film 14. A 50 μm-thick Shoalomer U, which is an ethylene / propylene / block copolymer resin film serving as a sealant layer 13 on the Al surface of the composite film
T30 film (manufactured by Showa Denko Plastic Products Co., Ltd., ethylene content in crystalline polymer 7.9% by weight, ethylene content in rubber component 43.6% by weight,
The melting peak temperature (Tm = 163.4 ° C.)) was dry-laminated using a polyurethane-based adhesive to prepare a laminated film 10 having a three-layer structure.

Example 2 A 50 μm-thick Tocello CP film RXC-17 (ethylene-propylene-block copolymer resin film serving as a sealant layer 13) was formed on the Al surface of the composite film 14 produced in Example 1. Ethylene content in crystalline polymer manufactured by Tosero Corporation
7.3% by weight, ethylene content in rubber component 42.5
% By weight, Tm = 164.6 ° C.) by dry lamination using a polyurethane-based adhesive to prepare a laminated film 10 having a three-layer structure.

<Example 3> A thickness of 50 to be a sealant layer 13 was formed on the Al surface of the composite film 14 prepared in Example 1.
μm ethylene-propylene block copolymer resin film (ethylene content in crystalline polymer: 6.3% by weight, ethylene content in rubber component: 40.8% by weight,
(Tm = 154.0 ° C.) was dry-laminated using a polyurethane-based adhesive to prepare a laminated film 10 having a three-layer structure.

Comparative Example 1 A 70 μm thick pyrene film CT, P1146 (manufactured by Toyobo Co., Ltd., which is an ethylene-propylene block copolymer resin film) was formed on the Al surface of the composite film 14 produced in Example 1. Ethylene content in crystalline polymer 4.1% by weight, ethylene content in rubber component 38.5% by weight, Tm = 162.
(2 ° C.) was dry-laminated using a polyurethane-based adhesive to prepare a three-layer laminated film.

Comparative Example 2 A 50 μm-thick ethylene / propylene / block copolymer resin film (ethylene content in a crystalline polymer of 8.2% by weight) was formed on the Al surface of the composite film 14 prepared in Example 1. , Ethylene content in rubber component: 48.6% by weight, Tm = 135.4 ° C)
Was dry-laminated using a polyurethane-based adhesive to prepare a three-layer laminated film.

Using the obtained five types of laminated films, a three-sided seal bag having a size of 125 mm × 175 mm was prepared by a heat sealing method (seal width: 6 mm) (see FIG. 2). This was filled with 200 ml of tap water, sealed by a heat sealing method, and retorted at 120 ° C. for 30 minutes. Thereafter, the high-speed tensile strength, the opening strength, the impact resistance test, and the film adhesion observation were performed on the heat-sealed portion by the following methods. Table 1 shows the results.
Shown in High-speed tensile strength; temperature 200 ° C, pressure 1kgf
The sealing strength (flow direction of the laminated film) of the heat sill portion heat-sealed under the conditions of / cm ² and a sealing time of 1 second was measured using a falling weight type high-speed impact tensile tester to 180.
° Peeled (pulling speed 3m / sec, sample width 15m
m, weight of falling weight 3000g). Opening strength: Measured according to JIS K7128 A method (Trouser tearing method). Impact resistance test: The packaging bag filled with tap water was repeatedly dropped horizontally at a temperature of 5 ° C. from a height of 1.5 m onto a concrete floor surface 30 times, and the state of the bag being broken was observed. …: No broken bag, with impact resistance X: Broken bag, impact resistance is not sufficient Sufficient film adhesion: The film adhesion after retort treatment was visually observed. : No fusion ×: fusion of inner films to each other Melting peak temperature: Measured in accordance with JIS K7121. Using a DSC measuring instrument manufactured by Seiko Electronic Industry Co., Ltd.
The melting peak temperature when melting from 30 ° C. to 200 ° C. at a rate of 10 ° C./min was measured.

[0020]

[Table 1]

Considering from Table 1, the polyethylene content of the crystalline polymer constituting the block polypropylene is 5% by weight or more and the polyethylene content of the rubber component is 40% by weight.
% By weight and the melting peak temperature of CPP is 140
° C or higher packaging bag has sufficient impact resistance,
It was found that the opening strength was weak and the opening could be performed smoothly. It was also found that a thickness of the sealant layer of 50 μm was sufficient (Examples 1, 2, and 3).

On the other hand, a packaging bag in which the polyethylene content of the crystalline polymer is 5% by weight or less and the polyethylene content of the rubber component is 40% by weight or less has no problem in the impact resistance, but is pulled at a high speed. It was found that the strength was weaker than in Examples 1 and 2, and the opening strength was stronger than in Examples 1 and 2 (Comparative Example 1).

Further, even when the polyethylene content of the crystalline polymer is 5% by weight or more and the polyethylene content of the rubber component is 40% by weight or more, the packaging bag having a melting peak temperature of CPP of less than 140 ° C. It was found that the unsealing strength was high, and fusion between the films occurred (Comparative Example 2).

[0024]

As described above, according to the present invention, by using a sealant layer thinner than the conventionally used sealant layer,
A retort-sterilizable packaging bag with excellent openability and impact resistance can be manufactured, and the material cost can be reduced by reducing the thickness of the sealant layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing an example of a layer structure of a laminated film used for a retort sterilizable packaging bag of the present invention.

FIG. 2 is an explanatory view showing an example of a retort sterilizable packaging bag of the present invention produced using the laminated film.

[Explanation of symbols]

 10 laminated film 11 base layer 12 intermediate layer 13 sealant layer 14 composite film 20 retort sterilizable packaging bag

Claims (3)

[Claims] 1. A retort sterilizable packaging bag comprising a laminated film in which a base material layer, an intermediate layer, and a sealant layer are sequentially laminated, wherein the sealant layer is made of an ethylene / propylene / block copolymer resin. A retort sterilizable packaging bag using an unstretched polypropylene film. 2. The crystalline polymer component constituting the ethylene / propylene / block copolymer resin has an ethylene content of 5% by weight or more, and the rubber component has an ethylene content of 40% by weight or more. Claim 1 characterized by the following:
A retort sterilizable packaging bag according to the above. 3. The non-stretched polypropylene film,
The retort sterilizable packaging bag according to claim 1 or 2, wherein a melting peak temperature by a DSC method (differential scanning calorimetry) is 140 ° C or more.