JPS598228B2 - food packaging bags - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a food packaging bag made from a laminated sheet of synthetic resin film, particularly a laminated sheet having a polyester or polyamide resin film layer and a heat-sealable synthetic resin film layer. It is.

BACKGROUND ART Food packaging bags made of sheets made of a laminated sheet of a heat-resistant synthetic resin film and a heat-sealable synthetic resin film such as polyethylene, or a sheet laminated with aluminum foil sandwiched between them, are conventionally known.

In recent years, when heat sterilizing packaged foods, a method of heating at high temperatures and for short periods of time has been proposed in order to prevent the food contents from being overcooked and to maintain their aroma, flavor, and appearance. However, the heat seal layer of the packaging bag (innermost layer of the bag)
Conventional packaging bags using polyethylene resin film are
When exposed to high temperatures, a large amount of components are extracted and transferred from the polyethylene resin layer to the food contents, and the heat-sealed portion cannot withstand high temperatures, making it unsuitable for high-temperature short-time heat sterilization.

Stretched polypropylene film is superior to polyethylene in terms of the above-mentioned migration properties and heat resistance of the heat-sealed part, but the temperature range in which it can be heat-sealed is narrow, making heat-sealing difficult and difficult to heat sterilize. It has the drawbacks of low impact resistance after treatment and low strength of the heat-sealed part, and is also prone to delamination problems.

Therefore, the object of the present invention is to provide a material that has excellent migration properties and heat resistance of the heat-sealed part when subjected to high-temperature, short-time heat sterilization treatment, and has improved impact resistance and strength of the heat-sealed part after the treatment. To provide a food packaging bag formed from a laminated sheet having a layer of heat-sealable resin film.

In order to achieve the above object, the present inventors developed food packaging using a polypropylene film having a specific degree of orientation and crystal morphology after being heat-sterilized at high temperature for a short time as a heat-sealable resin film layer. Bag for use (Special Publications Showa 4)
9-70792: Japanese Patent Publication No. 53-31437) and a food packaging bag further provided with a layer of thermoplastic resin film having a specific impact absorption coefficient (Japanese Patent Application No. 48-68295:
Special Publication No. 54-29959) was developed.

The inventors of the present invention have further developed a food packaging sheet made of a laminated sheet consisting of at least two layers: an inner layer of an ethylene-propylene block copolymer resin film and an outer layer of a polyester resin or polyamide resin film. In the bag, the ethylene-propylene block copolymer resin film is characterized in that (4) the copolymer molecules are essentially block-copolymerized ethylene-propylene copolymer molecules; an insoluble component; (B)
, the copolymer molecule consists of a block copolymerized part and a random copolymerized part, and the ethylene content is 10 to 50% by weight.
, a random index of 1.9 or less, p- at room temperature
It has been found that the above object can be achieved by a food packaging bag characterized by comprising a component soluble in xylene.

In the food packaging bag of the present invention, between the inner layer of the ethylene-propylene block copolymer resin film and the outer layer of the polyester resin or polyamide resin film, KI=S/7 [here, KI is impact Shock absorption represented by the absorption coefficient, S is the tensile strength (Kg) at 30% elongation of the resin film after retort treatment, and E is the tensile modulus of elasticity (Kg/Cll) of the resin film after retort treatment. By providing a layer of a thermoplastic resin film having a coefficient of 1.0×10 −4 or more, a food packaging bag with further improved impact resistance can be obtained. or,
By providing a layer of aluminum foil between the inner layer of the ethylene-propylene block copolymer resin film and the outer layer of polyester resin or polyamide resin film, gases, especially oxygen, can be prevented from permeating into the bag. It is possible to obtain a food packaging bag with improved preservation of the food contained therein.

By providing an intermediate layer between the shock-absorbing layer and the metal foil layer, it is possible to obtain a food packaging bag with improved impact resistance and food preservation. One novel feature of the food packaging bag of the present invention is that a specific ethylene-propylene block copolymer resin film is selected and used for the heat-sealable resin layer.

That is, the ethylene-propylene block copolymer used in the food packaging bag of the present invention is composed of a component (B) that is insoluble in p-xylene and a component (B) that is soluble at room temperature. The copolymer molecule is essentially an ethylene-propylene block copolymer, and the soluble component I3) consists of a block copolymerized portion and a random copolymerized portion of the copolymer molecule, and the ethylene content is 1.
It is 0 to 50% by weight. That is, it is a semi-block copolymer. The proportion of the soluble component (B) containing the random copolymerized portion is 1% of the infrared absorption spectrum of the copolymer.
Based on the measured values of the absorption intensities at 1500 fL-1 and 968 crrL-1, the formula 0-υυ0''C (where R is a random index, All5O and A968 are the absorption intensities C3 and C2 is the molar content of propylene and ethylene, respectively) The ratio must be such that the random index defined by C2 is 1.9 or less, and 1.
The ratio is preferably 5 or less.

The invention will be further described below with reference to the accompanying drawings.

Figure 1 of the attached drawings shows an example of the food packaging bag of the present invention comprising a polyester resin or polyamide resin layer and a heat-sealable resin layer, and Figure 2 shows an example of the food packaging bag of Figure 1. , an example of a bag further provided with a shock-absorbing thermoplastic resin layer, Fig. 3 is a bag in which a metal foil is further provided on the food packaging bag of Fig. 1, and Figs. 4 to 6 are examples of the food packaging of Fig. 3. FIG. 3 is a schematic cross-sectional view showing an example of a bag in which a shock-absorbing resin layer is further provided on the bag.

In Fig. 1, a layer 1 of ethylene-propylene block copolymer resin film is the innermost layer of the bag and is heat-sealed in a heat-sealing section 3, and a polyester resin or polyamide resin film layer 2 is placed on the outside. are layered.

The proportions of components (B and l) contained in the ethylene-propylene block copolymer of the inner layer 1 are not particularly specific, but the components (B) are 60 to 98% by weight, and the component (B) is 40% by weight.
~2 weight? It is preferable that the composition is 80 to 95.
It is more preferable that the amount of component (B) is 20 to 5% by weight. Also, the weight of ingredients is usually 0.1 to 20? , preferably 0.5 to 10% by weight, and component (B) usually 10 to 10% by weight.
It contains an ethylene content of 50% by weight, preferably 20-40% by weight. When the ethylene content is high, the infrared absorption vector is 1380 cm-1 and 1460 CTI
From the absorption intensity of L-1, and in the case of low content, 736
cTn-1 and 720? It can be determined from the absorption intensity of −1. The innermost layer 1 does not need to have a particular thickness, but typically ranges from about 30 to 100 microns, and from 40 to 8 microns thick.
Preferably, it is in the range of 0μ. The film of the inner layer 1 is preferably a stretched film, but may be an unstretched film. Inner layer 1 film is 200-350
Heat-sealing can be achieved by heat-pressing at a temperature in the range of °C. Examples of the resin used for the polyester resin or polyamide resin layer 2 are polyesters such as polyethylene terephthalate, polyethylene terephthalate-inphthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene oxybenzoate, and polycaprolactam. , polylaurinlactam, polyhexamethylene adipamide, polyhexamethylene sebacamide, poly-1,4-cyclohexylene adipamide, and mixtures thereof.

The polyester resin or polyamide resin layer 2 does not need to have a specific thickness, but is usually in the range of 1 to 30 microns, preferably 5 to 20 microns. In FIG. 2, a layer 4 of shock-absorbing thermoplastic resin film, and in FIG. 3, a layer 5 of aluminum foil are sandwiched and laminated between layers 1 and 2. Furthermore, in FIGS. 4 to 6, both the shock-absorbing thermoplastic resin layer 4 and the aluminum foil layer 5 are laminated as intermediate layers between layers 1 and 2, and the shock-absorbing thermoplastic resin layer 4 and the aluminum foil layer 5 are laminated as intermediate layers between layers 1 and 2. In the example of FIG. 4, the layer 4 is between the ethylene-propylene block copolymer resin layer 1 and the aluminum foil layer 5, and in the example of FIG. It is provided between the resin layers 2 and, in the example shown in FIG. 6, on both of them. That is, the shock absorbing layer 4 may be provided on either one of the layers of the three-layer laminated bag shown in FIG. 4, or may be provided on both. The thermoplastic resin used for the shock absorption layer 4 has a shock absorption coefficient KI defined above of 1.0×10-4d.
Above, preferably 2.0×10 −4 d or more.

KI is measured by the following method. That is, a sample heat-treated at 135° C. for 10 minutes in a retort was subjected to a tensile test in the machine direction of the film and in a direction perpendicular to this at room temperature and a tensile rate of 200 mm/Mi.
Tensile strength S (Kg) and tensile modulus E (K
9/Cril) is measured, and from this value, KI in each direction is calculated according to the formula defined above, and the smaller of the KI values in both directions is taken as the impact absorption coefficient.

Examples of thermoplastic resins suitable for forming the shock absorbing layer 4 include polycaprolactam, polylaurinlactam, polyhexamethylene adipamide, polyhexamethylene sebacamide,
Polyamides such as poly-1,4-cyclohexyleneadipamide, copolyamides, polydioxydiphenylmethane carbonate, polydioxydiphenylethane polycarbonate, polydioxydiphenyl-2,2
- polycarbonates such as proban carbonate, poly-p-xylene glycol biscarbonate, polyoxyethylene-ethylene terephthalate, poly-1,
4-oxybutylene-1,4-butylene terephthalate, polyoxyethylene-ethylene terephthalate/isophthalate, poly-1,3-oxypropylene-1,4
-butylene terephthalate, poly-1,2-oxypropylene-1,4-butylene terephthalate, poly-1,
Polyester polyethers such as 4-oxybutylene-oxyethylene-ethylene terephthalate, poly-epsilon-caprolactone polyethylene terephthalate, poly-epsilon-caprolactone-polyethylene terephthalate/
Polyester polylactones such as isophthalates.

The polymer films exemplified above can be used after being stretched in a uniaxial or biaxial direction, or can be used in an unstretched form. In addition to the polymer films mentioned above,
For those with stretched polypropylene film, 1.9
It has a shock absorption coefficient of x10-4d or more and can be used as the shock absorption layer of the bag of the present invention.

The shock-absorbing thermoplastic resin film forming the shock-absorbing layer 4 of the bag of the present invention has a melting point higher than that of the ethylene-propylene block copolymer film forming the heat-sealable innermost layer 1. It is also desirable in terms of shape retention during heat sterilization.

Further, it is desirable that this resin film has a surface free energy of 35 dynes/0 m or more, preferably 40 dynes/0 fn or more, from the viewpoint of preventing delamination and improving impact resistance after heat sterilization treatment. The above-mentioned surface free energy value is a value determined by the method of ASTM D78-67. In order to satisfy the above conditions of melting point and surface free energy, it is preferable to use a film made of polyamide resin, polycarbonate resin, or polyester polyether resin for the shock-absorbing resin layer, such as nylon 6, nylon 6-6, or A nylon 12 film is most suitable.

These films usually have poor dimensional stability under moist heat conditions, but when present as an intermediate layer in the bag of the present invention, they have good dimensional stability and are not difficult to heat during heat sealing and heat sterilization. It doesn't cause any trouble. Shock absorption layer 4
The thickness is usually in the range of 5 to 40μ, preferably 15 to 30μ.
The thickness of the aluminum foil layer 5 is usually in the range of 5 to 30 μ, preferably in the range of 7 to 15 μ, but it is not necessarily within this range. Layer 1 mentioned above
A laminated sheet consisting of and 2, 1 and 2 and 4, 1 and 2 and 5, or 1 and 2 and 4 and 5 is obtained by bonding the films or foils of these layers by any known means to form a laminate sheet. be able to.

For example, these layers can be bonded together using an adhesive. In this case, known adhesives such as isocyanate adhesives, epoxy adhesives, adhesives made of thermosetting resins such as isocyanate-epoxy adhesives, synthetic rubber adhesives, and adhesives made of thermoplastic resins may be used. Any adhesive can be used. However, the above-mentioned isocyanate-based, epoxy-based and isocyanate-epoxy-based adhesives are preferred. When bonding each layer of film and foil using an adhesive, the surface of the ethylene-propylene block copolymer film and/or polyester resin or polyamide resin film to be bonded is
It can be treated with ozone, corona discharge, flame and/or oxidizing agents to improve its adhesion.

The adhesion of each layer can also be carried out not by adhesive but by extrusion coating.

In this case, it is preferable to apply an anchoring agent such as a titanate ester or an isocyanate compound to the surface of the substrate to be coated, for example, aluminum foil. When providing a shock absorbing layer as an intermediate layer, polyamides such as nylon 6 and nylon 12, which are particularly suitable for the shock absorbing layer, are excellent hot melt adhesives, so if they are used as the shock absorbing layer, this layer will adhere. It has the advantage that it acts as an adhesive layer and does not require the use of a separate adhesive.

The ethylene-propylene block copolymer resin, polyester resin, or polyamide resin, and impact-absorbing thermoplastic resin forming the above-mentioned layers 1, 2, and 4 may be used within the range that does not impede achievement of the objects of the present invention. , other resins,
Natural or synthetic rubbers, plasticizers, lubricants, fillers, colorants,
Known additives such as stabilizers and antistatic agents can be optionally added.

From the laminated sheets described above, a pair of laminated sheets may be laminated using any known method, for example, so that the ethylene-propylene block copolymer film layers face each other, and heated to form the peripheral edge of the desired bag. The food packaging bag of the present invention can be made by a sealing method.

Methods for heat-sealing are known, such as methods for heating the required portions from the outside of the laminated seal, such as heating ovens, heating knives, heating wires, impurity seals, or ultrasonic sealing or induction heating sealing. Methods such as internal heating can be used.

Filling the bag obtained as described above with the food contents,
If necessary, the inside of the bag is degassed by any known method, such as vacuum deaeration, hot filling deaeration, steam deaeration, steam injection deaeration, or pressure deaeration, or the contents of the food are removed. is heated and sterilized, and then the food content is sealed by heat-sealing the food filling opening.

The package filled with the food content and sealed is suitable for heat sterilization, particularly high temperature short-time sterilization.

The heat sterilization treatment is carried out at a temperature of 115° C. to 160° C., and in the case of high-temperature short-time heating, it is carried out at a temperature of 130 to 160° C. A short time such as 10 seconds to 10 minutes is sufficient for the sterilization process. As a result, the flavor of the food contents is maintained, and deterioration or spoilage can be prevented. The heat sterilization treatment can be performed by either a batch method or a continuous method.

However, since the food packaging bag of the present invention can perform heat sterilization in an extremely short time, it is particularly suitable for continuous use. The packaging bags of the present invention can seal and sterilize a very wide range of foods.

Examples of foods that are particularly suitable for filling and sealing in the packaging bag of the present invention are various stews such as cooked curry, cooked hash, borscht, beef stew, various gravies such as meat sauce, sweet and sour pork, sukiyaki, and Chinese bean paste. , Happo greens, boiled asparagus, simmered tuna cream, etc., various vegetables, seafood and/or livestock products stewed, steamed and boiled products: Various soups such as consommé, potage, miso soup, pork soup, kenchin soup, etc. Soup: rice, sekihan, kamameshi, fried rice, pilaf,
Rice such as porridge: Various types of noodles such as spaghetti, soba, udon, ramen, and noodles: Foods to accompany kamameshi mix and Chinese soba mix, favorite foods such as boiled azuki, zenzai, and anmitsu: Meat dumplings, bread Cooked or semi-cooked meat or fish products such as park, beef steak, roast pork, sautéed pork, corned beef, ham, sausage, grilled fish, yakiniku, yakitori, roast chicken, pork chunks, fish dumplings, bacon, kamaboko, etc. It is a cooked food.

The food packaging bag of the present invention can be heat sterilized at high temperature for a short time by using the aforementioned specific ethylene-propylene block copolymer resin film as the innermost layer material of the bag.

That is, even when the food packaging bag of the present invention is subjected to sterilization treatment at a high temperature such as 150°C, the resin component is not extracted by the food contained therein, and the bag is made of ethylene-propylene block copolymer resin. No delamination occurs at the bonding surface between one layer and another layer. Furthermore, according to the present invention, by using the above-mentioned ethylene-propylene block copolymer resin film, not only the heat sealing operation is facilitated, but also the formed heat-sealed portion has a sufficient seal even after high-temperature heat sterilization. It maintains strength and impact resistance, as well as excellent sealing performance. Furthermore, according to the present invention, by providing a shock absorbing layer between the ethylene-propylene block copolymer resin and the aluminum foil, the shock resistance after high temperature heat treatment is further improved, and pinholes caused by vibration are prevented. Occurrence can be prevented. The present invention will be further explained with reference to Examples below.

In the examples, parts and percentages are by weight unless otherwise specified. Example 1 Insoluble in p-xylene at room temperature, ethylene content 1.1%
92 parts of an essentially block propylene ethylene block copolymer of A 70μ thick film of propylene ethylene copolymer consisting of 12
A 1:1 mixture of ethylene glycol and propylene glycol and a 10:1 mixture of terephthalic acid and isophthalic acid are used as monomers between each layer. A mixture of polyester resin (
Relative viscosity ηRel-1.12, 0.5% methyl-ethyl ketone solution, 150 parts of 20% methyl ethyl ketone solution with 3'C; hydroxyl value, 33), and 3 moles of tolylene diisocyanate per mole of trimethylolpropane. Laminate with an adhesive mixed with 4 parts of a 75% ethyl acetate solution of the product obtained by polyaddition reaction in advance, with the polypropylene film serving as the inner layer, and the periphery on three sides,
Heat sealing was performed at 250° C. for 0.5 seconds under a pressure of 3 kg/Cril to obtain a bag with a size of 130 mL×170 mm.

Heat seal strength is 7.1k9/2? It was warm. It was filled with 180 ml of a mixture of water and salad oil and subjected to high temperature retort sterilization treatment at 120°C for 30 minutes. When these 100 bags were dropped 10 times from a height of 1.2 m onto a concrete floor at a content temperature of 5°C, the percentage of bags that were broken was 2.
It was 7%. Fill this bag with instant curry and add 1
Those that had been retort sterilized for 20 to 30 minutes were durable enough to withstand transportation and handling during the winter, and had sufficient strength as commercial products. Example 2 A polypropylene ethylene block copolymer film used for the inner surface is insoluble in p-xylene at room temperature and has an ethylene content of 2.

92 parts of a 1% essentially block propylene ethylene copolymer and 8 parts of a semiblock propylene ethylene copolymer soluble in p-xylene at room temperature, having an ethylene content of 27% and a random index of 1.88. Consists of.

A bag was obtained in the same manner as in Example 1 except that a 70 μm thick film of propylene ethylene copolymer was used. The seal strength was 7.0 kg/2 cfrL width. Retort sterilization treatment was performed in the same manner as in Example 1, and a similar drop test was conducted. The percentage of bags that were torn was 37%. Comparative Example 1 As a propylene ethylene block copolymer film used for the inner surface, 94 parts of an essentially blocky propylene ethylene copolymer that is insoluble in p-xylene at room temperature and has an ethylene content of 2.1%, and p-xylene at room temperature - 6 parts of a semiblock propylene ethylene copolymer which is soluble in xylene and has an ethylene content of 26% and a random index of 1.97.

A bag was obtained in the same manner as in Example 1 except that a 70 μm thick film of propylene ethylene copolymer was used. The seal strength of the bag was 5.6 kg/2 CTL width. In the same manner as in Example 1, retort sterilization was performed and the same drop test was performed, and the percentage of bags that were torn was 74%. Many of these bags were torn during transportation and handling during the winter, so they could not be used as actual products. Example 3 A 50μ thick film of the same propylene ethylene block copolymer as used in Example 1 and an impact absorption coefficient K=
2.08 x 10-4 (71L) 15μ thick stretched nylon-6 film and 9μ thick aluminum foil, 1
2μ thick polyethylene terephthalate film,
In this order, each layer was laminated using the same adhesive used in Example 1, and a bag was obtained in the same manner as in Example 1.

This was filled with shrimp curry and sterilized in a high temperature short time retort at 135°C for 10 minutes. The shrimp had better texture and texture than those sterilized at 120°C, and were delicious. 100 bags filled with a mixture of water and salad oil and sterilized in a retort at 1350C for 10 minutes
．． When dropped from 2 meters onto a concrete floor, 13% of the bags were broken. The bag did not break during transportation or handling during the winter, and had sufficient strength as a commercial product. The three-layer bag of Example 1 using the same innermost layer material as this example was heated to 135°C.
When high-temperature, short-time retort sterilization was performed for 110 minutes, some deterioration of the inner polypropylene layer was observed, and when the drop test was performed, the number of broken bags due to drops increased.

Example 4 The same polypropylene ethylene copolymer film used in Example 1, the same 15μ thick nylon-6 film used in Example 3, and the 12μ thick polyethylene terephthalate film were prepared in this order. ,
The layers were laminated using the same adhesive used in Example 1, and a bag was obtained in the same manner as in Example 1.

Filled with eel bread park "eel hamburger" 1
Retort sterilization treatment was performed at 35° C. for 10 minutes. The eel's texture and texture were maintained extremely well, and it was extremely delicious. This item is transported during winter,
There are no pinholes or bag tears caused by cargo handling.
It had sufficient strength for practical use.

Example 5 A 15μ thick biaxially oriented nylon-6 film and a 60μ thick propylene ethylene block copolymer film as used in Example 2 were prepared using the same adhesive as used in Example 1. Laminated.

Hot sealing was performed at 250°C for 0.5 seconds under a pressure of 3 kg/(7ii) to obtain a bag of 130 mm x 170 bags.

The seal strength was 5.0 kg/2 cIn width. This was filled with Panpaque and retort sterilized at 120°C for 30 minutes. When 100 bags containing Panpark were dropped 10 times from a height of 1.2 m onto a concrete floor, 31% of the bags were broken. This is winter transportation,
It withstood the load.

[Brief explanation of drawings]

The drawing is a sectional view schematically showing the structure of the food packaging bag of the present invention. Fig. 1 shows an example of a bag comprising a layer of ethylene-propylene block copolymer resin and a layer of polyester resin or polyamide resin; The figure shows layers of aluminum foil, 4th to 6th
The figure shows an example of a bag having a layer of shock-absorbing thermoplastic resin and a layer of aluminum foil in between. The symbols in the drawings indicate the following parts. 1... Ethylene-propylene block copolymer resin layer, 2... Polyester resin or polyamide resin layer, 3... Heat seal portion, 4...・Shock absorbing resin layer, 5
...Aluminum foil layer.

Claims (1)

[Scope of Claims] 1. A food packaging bag formed of a laminated sheet having at least two layers: an inner layer of an ethylene-propylene block copolymer resin film and an outer layer of a polyester resin or polyamide resin film. The ethylene-propylene block copolymer resin film comprises (A) a component insoluble in p-xylene at room temperature, which is an ethylene-propylene copolymer in which the copolymer molecules are substantially block copolymerized; (B), the copolymer molecule consists of a block copolymerized part and a random copolymerized part, has an ethylene content of 10 to 50% by weight, has a random index of 1.9 or less, and is soluble in p-xylene at room temperature. A food packaging bag characterized by comprising the following ingredients: 2 A food packaging bag formed of a laminated sheet having at least two layers, an inner layer of an ethylene-propylene block copolymer resin film and an outer layer of a polyester resin or polyamide resin film, wherein the ethylene-propylene block copolymer resin film is The polymer resin film comprises (A) a component insoluble in p-xylene at room temperature, the copolymer molecules of which are substantially block copolymerized ethylene-propylene copolymer molecules; and (B) a copolymer. Food packaging consisting of a block copolymerized part and a random copolymerized part of the combined molecules, an ethylene content of 10 to 50% by weight, a random index of 1.9 or less, and a component soluble in p-xylene at room temperature. K is provided between the inner layer of the ethylene-propylene block copolymer resin film and the outer layer of the polyester resin or polyamide resin film.
_ I = S/E [Here, K_ I is the impact absorption coefficient, S is the tensile strength (kg) at 30% elongation of the resin film after retort treatment, and E is the tensile elasticity of the resin film after retort treatment. 1. A food packaging bag characterized by having a layer of a thermoplastic resin film having an impact absorption coefficient of 1.0 x 10^-^4 cm^2 or more, expressed as 1.0 x 10^-^4 cm^2. 3 A food packaging bag formed of a laminated sheet having at least two layers, an inner layer of an ethylene-propylene block copolymer resin film and an outer layer of a polyester resin or polyamide resin film, wherein the ethylene-propylene block copolymer resin film is The polymer resin film comprises (A) a component insoluble in p-xylene at room temperature, the copolymer molecules of which are substantially block copolymerized ethylene-propylene copolymer molecules; and (B) a copolymer. Food packaging consisting of a block copolymerized part and a random copolymerized part of the combined molecules, an ethylene content of 10 to 50% by weight, a random index of 1.9 or less, and a component soluble in p-xylene at room temperature. 1. A food packaging bag comprising an aluminum foil layer between the inner layer of an ethylene-propylene block copolymer resin film and the outer layer of a polyester resin or polyamide resin film. 4. A food packaging bag formed of a laminated sheet having at least three layers: an inner layer of ethylene-propylene block copolymer resin film, an intermediate layer of aluminum foil, and an outer layer of polyester resin or polyamide resin film, The ethylene-propylene block copolymer resin film comprises (A) a component insoluble in p-xylene at room temperature, in which the copolymer molecules are substantially block-copolymerized ethylene-propylene copolymer molecules; (B), the copolymer molecule consists of a block copolymerized part and a random copolymerized part, has an ethylene content of 10 to 50% by weight, has a random index of 1.9 or less, and is soluble in p-xylene at room temperature. A food packaging bag consisting of ingredients,
K_ I = S/E between the ethylene-propylene block copolymer resin film layer and the aluminum foil layer, or between the aluminum foil layer and the polyester resin or polyamide resin layer, or both. [K here
_ I is the impact absorption coefficient, S is the tensile strength (kg) at 30% elongation of the resin film after retort treatment,
E is the tensile elastic modulus (k
1. A food packaging bag characterized by having a layer of a thermoplastic resin film having an impact absorption coefficient expressed as g/(cm^2) of 1.0 x 10^-^4 cm^2 or more.