JP2003192803A - Heat sealable film and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sealable film having a sufficient heat seal strength, and also excellent in low temperature impact resistance strength without having a melt adhesion of inner surface after its heat treatment. <P>SOLUTION: This heat sealable film is characterized by being equipped with a heat seal layer obtained from (C) an ethylenic polymer composition consisting of (A) an ethylene polymer having 0.960-0.975 g/cm<SP>3</SP>density and (B) an ethylene/α-olefin random copolymer having >0.900 and ≤0.920 g/cm<SP>3</SP>density. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-fusible film having heat seal strength and low temperature impact strength obtained from an ethylene polymer composition. More specifically, the present invention relates to a heat-fusible multilayer film suitable for packaging a retort food and a retort food package using the same.

[0002]

2. Description of the Related Art Due to various social changes such as aging, nuclear family, increasing number of single employees, dual-income generation, aging marriage age, diversification of food culture, reduction of cooking time, convenience Due to the demand for sex, after putting pre-cooked food in a bag and sealing it, purchase so-called retort food that has been sterilized under pressure and heat, and heat the retort food together with the bag in hot water when necessary. It is becoming more common to take things out and use them for meals. Such retort foods are
Not only for general households but also for commercial use as the number of restaurant chain stores increases. Therefore, a packaging material that can package a large amount of food at once is required.

Since retort-packed foods are stored at room temperature for a long period of time or are refrigerated / frozen at times, the film used as a material thereof is required to have high heat-sealing strength and low-temperature impact strength so as not to be damaged by the heat-sealing portion. ing. Moreover, retort pouch foods are filled with food and sealed 10
In order to sterilize the retort in a high-temperature and high-pressure kettle at a temperature of 0 to 140 ° C, it is required from the viewpoint of food quality control to maintain the heat resistance and heat seal strength of the heat seal portion that can withstand it.

Conventionally, for this purpose, a film obtained from a composition of polypropylene and an ethylene / α-olefin copolymer rubber, a film obtained from a polypropylene block copolymer, or the polypropylene block copolymer and ethylene / ethylene Films and the like obtained from a composition with an α-olefin copolymer rubber are used because they are excellent in heat resistance and low temperature impact resistance. However, since all of these films use a propylene-based polymer as a main component, they tend to be inferior in impact resistance, particularly impact strength at low temperatures.

Various films containing an ethylene-based polymer as a main component have been proposed to improve the impact resistance. For example, in Japanese Unexamined Patent Publication No. 9-174776, a mixture of high-density polyethylene and a soft polymer, specifically a density of 0.9
Laminate film for retort foods high density polyethylene and density of 45~0.965g / cm ³ is between the seal layer of a mixture of 0.900 g / cm ³ or less of soft polymer are disclosed. Further, in JP-A-10-87909, a linear low-density polyethylene having a density of 0.935 to 0.945 g / cm ³ and a density of 0.955 to 0.970 are disclosed.
A retort sealant film comprised of a composition with g / cm ³ of high density polyethylene is disclosed.

However, even a film obtained from a composition obtained by mixing an ethylene-based polymer having such a density range,
The impact resistance is still insufficient, and the one having satisfactory thermal fusion resistance has not been obtained yet.

[0007]

Therefore, the present invention has developed a heat-fusible film which has sufficient heat-sealing strength and has excellent low temperature impact resistance without fusion of the inner surface even after heat treatment. As a result of various studies aimed at achieving the above, it was found that a film obtained from a composition with an ethylene polymer having a specific density can achieve such an object.

[0008]

[Means for Solving the Problems]

SUMMARY OF THE INVENTION The present invention has a density of 0.960 to 0.97.
5 g / cm ³ ethylene polymer (A) and density 0.90
0 g / cm ³ a exceeds 0.920 g / cm ³ or less of the ethylene · alpha-olefin random copolymer (B) and the ethylene-based polymer composition (C), preferably a density of 0.940
The heat-fusible film is characterized by comprising a heat-fusion layer obtainable from the ethylene-based polymer composition (C) in the range of 0.950 g / cm ³ .

The present invention relates to a heat fusible film in which a laminate layer made of an ethylene polymer (D) is laminated on one surface of the above heat fusible layer.

In the present invention, the ethylene polymer composition (C) contains 0.5 to 1.5% by weight of an antiblocking agent.
The present invention relates to a heat-fusible film containing the ethylene-based polymer (D) in an amount of 0.05 to 1.0% by weight of an antiblocking agent.

The present invention relates to a heat fusible film in which the ethylene / α-olefin random copolymer (B) can be obtained by a single site catalyst.

The present invention relates to a heat-fusible multilayer film and a film for packaging retort food, which comprises a heat-fusible layer comprising an ethylene polymer composition (C) on at least one side of a substrate.

The present invention relates to a retort food package which is heat-sealed with a film for packaging a retort food product, which comprises a heat-sealing layer made of an ethylene polymer composition (C) on at least one surface of a substrate.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Ethylene Polymer (A) The ethylene polymer (A) according to the present invention has a density of 0.9.
60 to 0.975 g / cm ³ , preferably 0.965 to
0.970 g / cm ³ of a homopolymer of ethylene or a copolymer of ethylene and a small amount of propylene, butene-1, heptene-1, hexene-1, octene-1, 4-methyl-pentene-1. It is a polymer mainly composed of ethylene, which is usually called high density polyethylene.
In addition, melt flow rate (MFR: ASTM D123
8 load 2160 g, temperature 190 ° C.) is not particularly limited as long as film formation is possible, but usually 0.5 to 20.
g / 10 minutes, preferably 1-10 g / 10 minutes, more preferably 1-7 g / 10 minutes.

If the density of the ethylene polymer is less than 0.960 g / cm ³ , the film obtained from the composition with the ethylene / α-olefin random copolymer (B) described below may have low heat resistance. On the other hand, the density is 0.975 g / c
If the ethylene polymer exceeds m ³ , the impact resistance may not be improved.

Ethylene / α-olefin random copolymerization
Body (B) The ethylene / α-olefin random copolymer (B) according to the present invention has a density of more than 0.900 g / cm ³ and a density of 0.
920 g / cm ³ or less, preferably 0.902 to 0.9
Ethylene in the range of 15 g / cm ³ and usually α-olefins having 3 to 10 carbon atoms, such as propylene, butene-1, heptene-1, hexene-1, octene-1, 4,
A random copolymer with -methyl-pentene-1
It is a polymer mainly composed of ethylene, which is also called so-called linear low-density polyethylene. Also, melt flow rate (MFR: ASTM D1238 load 2160g,
The temperature (190 ° C.) is not particularly limited as long as film formation is possible, but is usually 0.5 to 20 g / 10 minutes, preferably 1 to 10 g / 10 minutes, more preferably 1 to 7 g / 10.
It is in the range of minutes.

As for the ethylene / α-olefin random copolymer having a density of 0.900 g / cm ³ or less, the film obtained from the composition with the ethylene polymer (A) may have poor heat resistance. , Density 0.920 g / cm ³
The ethylene / α-olefin random copolymer having a viscosity of more than 100% may not be improved in impact resistance.

The ethylene / α-olefin random copolymer (B) has a molecular weight distribution (weight average molecular weight:
The ratio of Mw and the number average molecular weight: Mn: Mw / Mn) is usually 1.5 to 4.0, preferably 1.8 to 3.5.
Is in the range. This Mw / Mn can be measured by gel permeation chromatography (GPC).

Ethylene Polymer (D) The ethylene polymer (D) according to the present invention has a density of 0.
895 to 0.975 g / cm ³ , preferably 0.900
-0.970 g / cm ³ of ethylene homopolymer or a copolymer of ethylene and a small amount of propylene, butene-1, heptene-1, hexene-1, octene-1, 4-methyl-pentene-1. Yes, it is usually a polymer mainly composed of ethylene, which is also called high-pressure low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, or high-density polyethylene. These ethylene-based polymers (D) are one component. Alternatively, it may be a composition comprising a polymer of two or more components. Among them, the density is 0.920
~ 0.960 g / cm ³ , and further 0.930-0.95
The range of 0 g / cm ³ is preferable because a film excellent in heat resistance and impact resistance can be obtained.

The ethylene polymer (D) forming the laminate layer according to the present invention includes a heat resistance stabilizer, a weather resistance stabilizer, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an antiblocking agent, an antistatic agent and an antistatic agent. Various additives usually used for polyolefins such as a clouding agent, a pigment, a dye, and an inorganic or organic filler may be added within a range not impairing the object of the present invention.

Among them, the antiblocking agent is added in an amount of 0.05 to
By adding 1.0% by weight, preferably 0.1 to 0.7% by weight, a heat-fusible film having excellent transparency and antiblocking properties can be obtained. If the amount of the antiblocking agent is less than 0.05% by weight, the resulting antifusible film has insufficient antiblocking effect,
On the other hand, if it exceeds 1.0% by weight, the transparency of the resulting heat-fusible film tends to deteriorate. As such an anti-blocking agent, various publicly known ones, for example, silica, talc, mica, inorganic compound particles such as metal oxides obtained by firing zeolite or further metal alkoxide, polymethyl methacrylate, melamine formalin resin, Organic compound particles such as melamine urea resin and polyester resin can be used. Among these, silica and zeolite are particularly preferable in terms of antiblocking property and transparency. The anti-blocking agent usually has an average particle size of 4.0 to 10.0 μm.
m, preferably in the range of 5.0 to 7.0 μm.

The ethylene / α-olefin random copolymer (B) according to the present invention is a differential scanning calorimeter (DSC).
There is one or a plurality of sharp peaks determined from the endothermic curve measured at a temperature rising rate of 10 ° C./min.
It is in the range of 0 to 120 ° C.

The ethylene / α-olefin random copolymer as described above can be prepared by a conventionally known production method using a single site catalyst. For example, an ethylene / α-olefin random copolymer can be prepared using a catalyst containing a transition metal metallocene compound. The catalyst containing this metallocene compound is preferably formed from (a) a metallocene compound of a transition metal, (b) an organoaluminum oxy compound, and (c) a carrier, and further, if necessary, with these components. (D) It may be formed from an organic aluminum compound and / or an organic boron compound.

It should be noted that a catalyst for olefin polymerization containing such a metallocene compound, and ethylene using the catalyst
A method for preparing an α-olefin random copolymer is described in, for example, JP-A-8-269270.

Ethylene Polymer Composition (C) The ethylene polymer composition (C) according to the present invention is an ethylene polymer (A) having a density in the range of 0.960 to 0.975 g / cm ³ . The density is preferably 60 to 80% by weight, more preferably 65 to 75% by weight, and the density is 0.900 g / c.
The ethylene / α-olefin random copolymer (B) in the range of more than m ³ and 0.920 g / cm ³ or less, preferably 40 to 20% by weight, more preferably 35 to 25% by weight. If the ethylene polymer (A) is less than 60% by weight, the heat resistance of the obtained film may not be improved, while if it exceeds 80% by weight, the impact resistance of the obtained film may be poor. The ethylene-based polymer composition (C) according to the present invention preferably has a density of 0.940-
0.955 g / cm ³ , more preferably 0.945 to
It is in the range of 0.950 g / cm ³ .

The ethylene polymer composition (C) forming the heat-sealing layer according to the present invention or the ethylene polymer (A) or the ethylene / α-olefin random copolymer constituting the ethylene polymer composition (C) Similarly, various additives may be added to the polymer (B) as long as the object of the present invention is not impaired. Similarly, by adding 0.5 to 3.0% by weight, preferably 0.7 to 2.0% by weight, of an antiblocking agent, heat fusion having excellent transparency and antiblocking property is obtained. It can be a film.

Heat-fusible Film The heat-fusible film of the present invention comprises a heat-fusible layer which can be obtained from the ethylene polymer composition (C). or,
The heat fusible film of the present invention comprises a heat fusible layer obtainable from the ethylene polymer composition (C) and a laminate layer composed of an ethylene polymer (D) layer. Further, the heat-fusible film of the present invention may have an intermediate layer made of an ethylene polymer between the laminate layer and the heat-fusion layer. The ethylene-based polymer forming the intermediate layer is the ethylene polymer (A), the ethylene / α-olefin random copolymer (B), the ethylene-based polymer composition (C) or the ethylene-based polymer (D). There is no particular limitation as long as it is composed of
It is preferable to use the ethylene polymer in the range of 0.960 g / cm ³ because a heat-fusible film excellent in heat resistance and impact resistance can be obtained.

The thickness of the heat-fusible film of the present invention is variously selected according to the application. For example, in the case of a single heat fusion layer, it is usually 40 to 120 μm, preferably 60 to 80 μm.
In addition, when it is composed of two layers of a laminate layer and a heat fusion layer, the thickness of the laminate layer is usually 20 to 60 μm,
It is preferably in the range of 30 to 40 μm, and the thickness of the heat fusible film is 20 to 60 μm, preferably 30 to 4
It is in the range of 0 μm. Furthermore, in the case of being composed of three layers provided with an intermediate layer, the thickness of the laminate layer is usually 10 to 30.
μm, preferably 15 to 20 μm, the thickness of the intermediate layer is 20
-60 μm, preferably 30-40 μm, the thickness of the heat-sealing layer is 10-30 μm, preferably 15-20 μm, and the thickness of the heat-sealing film is 40-120 μm.
m, preferably in the range of 60 to 80 μm.

The heat-fusible film of the present invention may be subjected to surface treatment such as corona treatment or flame treatment on one side or both sides, if necessary. It is preferable to subject the layer in contact with the base material to a surface treatment because the laminate strength is improved when the base material is laminated on the layer.

The heat-fusible multilayer film of the present invention is formed by laminating a base material on one surface of the heat-fusible film. Examples of such a substrate include a film made of polyester typified by polyethylene terephthalate and polyethylene naphthalate, a polycarbonate film, nylon 6,
A thermoplastic resin film such as a polyamide film made of nylon 66, an ethylene / vinyl alcohol copolymer film, a polyvinyl alcohol film, a polyvinyl chloride film, a polyvinylidene chloride film, or a polyolefin film such as polypropylene, or an aluminum film. Composed of foil, paper, etc. The substrate made of such a thermoplastic resin film may be a non-stretched film or a uniaxially or biaxially stretched film. Of course, the base material may be one layer or two or more layers. or,
The thermoplastic resin film may be a film obtained by vapor deposition of an inorganic substance such as aluminum, zinc or silica, or an oxide thereof.

The heat-fusible film of the present invention can be produced by various known methods. For example, each of the ethylene polymer (A) and the ethylene / α-olefin random copolymer (B) constituting the heat-sealing layer is mixed in a predetermined amount, and then directly fed into a film forming machine to obtain T-. A method of forming a film by using a die, a cyclic die, or the like, and previously mixing the ethylene polymer (A) and the ethylene / α-olefin random copolymer (B) in a predetermined amount, and melt-kneading with an extruder or the like. A method of obtaining a heat-fusible film by forming a film using a T-die, a ring die or the like after obtaining the ethylene-based polymer composition (C). In order to produce a heat-sealing film having a laminate layer, the heat-sealing layer previously obtained by the above-mentioned method and the film obtained by the same method using the ethylene polymer (D) constituting the laminate layer are pasted together. A polymer for forming a heat-sealing layer, a laminate layer and, if necessary, an intermediate layer may be coextruded and molded into a heat-fusible film by a method of combining them or using a multi-layer die having two or three layers.

In order to obtain a heat-fusible multi-layer film laminated with a substrate, the previously-obtained substrate and the heat-fusible film may be stuck together by a dry lamination method or the like. The heat-fusible film can be produced by coextrusion and laminating.

When laminating the heat-fusible film and the substrate, the surface of the heat-fusible film or the substrate is coated with an adhesive such as polyethyleneimine or urethane in order to increase the adhesiveness with the substrate. Anchor treatment may be performed, or a maleic anhydride-modified polyolefin may be laminated.

Film for Packaging Retort Foods The film for packaging retort foods of the present invention comprises a heat-fusible film laminated on at least one side of the substrate, the surface of which is obtained from the ethylene polymer composition (C). It is a heat-fusible multi-layer film comprising a heat-fusible layer. As a substrate used for such a retort food packaging film,
There is no particular limitation as long as it is the above-mentioned substrate, but it is usually a polyester layer, a polyamide layer, a polyester layer /
Aluminum foil, polyester layer / polyamide layer / aluminum foil, polyamide layer / polyvinylidene chloride layer / polyester layer, etc. are used.

Retort Food Package The retort food package of the present invention comprises a heat-fusible multi-layer film having a heat-fusible layer obtainable from the ethylene-based polymer composition (C) on the surface of the substrate layer. The retort food packaging film to be constructed is used to package (fill) the food (the material to be packaged), which is the content, with the heat fusion layer inside, and heat seal the heat fusion layer forming the film. As a result, the contents are hermetically packaged. The items to be packaged in the retort food package according to the present invention are not limited to foods, but are not limited to foods in a narrow sense, and include all products such as pharmaceuticals that are subjected to retort sterilization.

[0036]

The heat-fusible film of the present invention has a sufficient heat-sealing strength when used as a packaging material, and particularly when used as a packaging material for retort foods.
Even after retort treatment at high temperature and high pressure for 30 minutes at ℃,
It has excellent impact resistance at a low temperature of −5 ° C., and has an unprecedented property such that it is difficult to cause inner surface fusion. Therefore, by utilizing such characteristics, it is suitable not only as a general food packaging material but also as a retort food packaging material. Further, the retort food package packaged using such a heat-fusible multilayer film has sufficient heat-sealing strength without fusion of the inner surface even after retort treatment and has excellent low-temperature impact resistance, so that it can be distributed. It is possible to reduce bag breaking troubles in the process.

[0037]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

The raw materials used in the examples and comparative examples are as follows. (1) Ethylene polymer-1 (high density polyethylene) manufactured by Mitsui Chemicals, Inc. (trade name: Hi-Zex, brand name: 220)
0J) Density; 0.968 g / cm ³ , MFR; 5.0 g / 10
Minutes. (2) Ethylene polymer-2 (single-site catalytic polymerization linear low-density polyethylene) manufactured by Mitsui Chemicals, Inc. (trade name: Evolue, brand name: SP05
10) Density 0.905 g / cm ³ , MFR; 1.0 g / 10
Minutes. (3) Ethylene polymer-3 (high density polyethylene) manufactured by Mitsui Chemicals, Inc. (trade name: Hi-Zex, brand name: 330)
0F) Density; 0.954 g / cm ³ , MFR; 1.1 g / 10
Minutes. (4) Ethylene polymer-4 (ethylene-propylene copolymer) manufactured by Mitsui Chemicals, Inc. (trade name: Toughmer P, brand name: P028
0) Density 0.870 g / cm ³ , MFR; 2.9 g / 10
Minutes. (5) Ethylene polymer-5 (multi-site catalytic polymerization linear low density polyethylene) manufactured by Mitsui Chemicals, Inc. (trade name: ULTOZEX, brand name: 40)
20 L) Density 0.940 g / cm ³ , MFR; 2.2 g / 10
Minutes.

The evaluation methods of the physical property values in Examples and Comparative Examples are as follows. The physical properties of the heat-fusible film were measured by dry laminating the heat-fusible film obtained in each Example and Comparative Example and a biaxially stretched polyamide film having a thickness of 15 μm using a urethane adhesive. The obtained multilayer film was used. <Evaluation of heat-resistant fusion resistance: Inner surface adhesion strength> The multilayer film was processed into a three-side sealed bag having a length of 240 mm and a width of 190 mm.
The three-sided sealed bag was sealed while being deaerated so that the heat-sealing layers were in close contact with each other, and retort treatment was performed at 120 ° C. and 123 ° C. for 30 minutes. After that, the contact portion of each heat-sealing layer was cut into a width of 15 mm, a T-shaped peeling test was performed at a pulling speed of 300 mm / min, and the inner surface adhesion strength (N / 15 mm) was measured. <Evaluation of low temperature impact resistance> The multilayer film was processed into a three-side sealed bag having a length of 240 mm and a width of 190 mm in the same manner as above.
This three-way seal bag was filled with 600 cc of water containing antifreeze and sealed, and retort treatment was performed at 120 ° C and 123 ° C for 30 minutes. After that, the sample was left to stand in an atmosphere of -5 ° C for 24 hours or more, and a weight of 1 kg was placed in the same atmosphere to give a weight of 0.
The bag was dropped horizontally from a height of 6 m and the number of bag drops until the bag was broken was measured. <Evaluation of heat-sealing property> The heat-sealing layers of the multi-layer film were superposed on each other and heat-sealed at a temperature of 0.2 MPa for 1 second. The heat-sealed portion was cut in a width of 15 mm, a T-shaped peel test was performed at a pulling speed of 300 mm / min to measure the strength, and the seal strength reaching the maximum point was shown as the saturated seal strength (N / 15 mm).

Example 1 As an ethylene polymer composition for a laminate layer, ethylene polymer-1: 65% by weight and ethylene polymer-2:
A composition obtained by adding 0.3% by weight of a synthetic zeolite having an average particle size of 5 μm as an anti-blocking agent to a mixture with 35% by weight is used as an ethylene polymer composition for a heat-sealing layer. : 65% by weight and ethylene polymer-2: 35% by weight, a composition comprising 1.46% by weight of a synthetic zeolite having an average particle diameter of 5 μm as an antiblocking agent, and an ethylene-based polymer for the intermediate layer. As a combined composition, a composition composed of a mixture of ethylene polymer-1: 65% by weight and ethylene polymer-2: 35% by weight was prepared, and the composition had a three-layer structure and a composition ratio of 1: 2: 1.
To obtain a heat-fusible film having a thickness of 60 μm by co-extrusion molding using a multi-type T-die method. The obtained heat-fusible film was subjected to corona discharge treatment on the laminate layer immediately before winding the film, and had a surface tension of about 42 dyn.
/ Cm. Table 1 shows the evaluation results of the obtained heat-fusible film.

Comparative Example 1 Ethylene polymer-3: 84.7% by weight and ethylene polymer-as an ethylene polymer composition for a laminate layer.
The composition obtained by adding 0.3% by weight of a synthetic zeolite having an average particle size of 5 μm as an anti-blocking agent to a mixture with 4: 15.3% by weight is used as an ethylene-based polymer composition for a heat-sealing layer, and ethylene is used. A composition prepared by adding 1.46% by weight of a synthetic zeolite having an average particle size of 5 μm as an antiblocking agent to a mixture of polymer-3: 84.7% by weight and ethylene polymer-4: 15.3% by weight, And an ethylene polymer as an ethylene-based polymer composition for the intermediate layer-
3: 84.7% by weight and ethylene polymer-4: 15.3
Compositions each consisting of wt.% Were prepared, and a film was formed by co-extrusion molding with a multi-type T-die method so as to have a composition ratio of 1: 2: 1 in a three-layer structure, and heat-melted to a thickness of 60 μm. An adhesive film was obtained. In the obtained heat-fusible film, the laminate layer was subjected to corona discharge treatment immediately before winding the film to have a surface tension of about 42 dyn / cm. Table 1 shows the evaluation results of the obtained heat-fusible film.

Comparative Example 2 As an ethylene polymer composition for a laminate layer, ethylene polymer-1: 40% by weight and ethylene polymer-5:
A composition obtained by adding 0.3% by weight of a synthetic zeolite having an average particle size of 5 μm as an antiblocking agent to a mixture with 60% by weight is used as an ethylene-based polymer composition for a heat-sealing layer. : 40% by weight and ethylene polymer-5: 60% by weight, a composition comprising 1.46% by weight of a synthetic zeolite having an average particle diameter of 5 μm as an antiblocking agent, and an ethylene-based polymer for the intermediate layer. As the combined composition, a composition composed of a mixture of ethylene polymer-1: 40% by weight and ethylene polymer-5: 60% by weight was prepared, and the composition had a three-layer structure and a composition ratio of 1: 2: 1.
To obtain a heat-fusible film having a thickness of 60 μm by co-extrusion molding using a multi-type T-die method. The obtained heat-fusible film was subjected to corona discharge treatment on the laminate layer immediately before winding the film, and had a surface tension of about 42 dyn.
/ Cm. Table 1 shows the evaluation results of the obtained heat-fusible film.

[0043]

[Table 1]

From the evaluation results shown in Table 1, the heat-fusible films obtained in the examples are significantly improved in low-temperature impact strength after retort treatment as compared with the heat-fusible films obtained in the comparative examples. It is also clear that the adhesion strength of the heat-sealing layer is low and it is difficult to cause the inner surface adhesion.

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Claims (8)

[Claims] 1. A density of 0.960 to 0.975 g / cm ^3.
Of ethylene polymer (A) having a density of 0.900 g / cm ³
And a heat-sealing layer obtainable from an ethylene-based polymer composition (C) with an ethylene / α-olefin random copolymer (B) of more than 0.920 g / cm ³ or less. Heat-fusible film. 2. A heat-fusible film comprising a laminate layer comprising an ethylene polymer (D) laminated on one surface of the heat-fusion layer according to claim 1. 3. The heat fusible film according to claim 1, wherein the ethylene polymer composition (C) has a density in the range of 0.940 to 0.950 g / cm ³ . 4. The ethylene-based polymer composition (C) contains 0.5 to 3.0% by weight of an anti-blocking agent, and the ethylene-based polymer (D) contains 0.05 to 3.0% of an anti-blocking agent.
The heat-fusible film according to any one of claims 1 to 3, which comprises 1.0% by weight. 5. The heat fusible film according to claim 1, wherein the ethylene / α-olefin random copolymer (B) can be obtained by a single site catalyst. 6. A heat-fusible multi-layer film comprising the heat-fusible layer according to claim 1 on at least one side of a substrate. 7. A retort food packaging film comprising the heat-fusible multilayer film according to claim 6. 8. A retort food packaging body, which is heat-sealed with the retort food packaging film according to claim 7.