JP2001310430A - Easily openable composite film and easily openable container made of polyethylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily openable composite film with good release appearance and heat resistance and with excellent opening properties and hermetic properties and an easily openable container made of polyethylene. SOLUTION: The easily openable composite film of the present invention is a composite film in which a seal layer (a layer A) and a base material layer (a layer B) are laminated and the layer A is a layer comprising 30-75 wt.% low density polyethylene a with a melt flow rate in a range of 2-20 g/10 min, 10-40 wt.% low density polyethylene b with a melt flow rate in a range of 50-300 g/10 min and the layer B is constituted of a layer comprising a polyethylene resin. In addition, the easily openable container made of polyethylene of the present invention consists of a lid material using the layer A face of such the easily openable composite film as this as a sealant layer and a container part made of polyethylene and the layer A face of the lid material and the layer A face of the lid material is constituted to be sealed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention has good heat resistance,
The present invention relates to an easily-openable composite film and an easily-openable polyethylene container having excellent appearance after peeling. More specifically, the present invention relates to an easily-openable composite film that can be suitably used as an easily-openable lid material for a polyethylene container, and an easily-openable polyethylene container using the easily-openable composite film as a lid material.

[0002]

2. Description of the Related Art In recent years, paper containers have increased as containers for dairy products such as yogurt, natto, instant noodles, etc. in response to the demand for clarity of printing accompanying diversification of designs and environmental problems at the time of disposal. I have. Usually, the inner surface of the paper container is coated with a polyethylene resin, and a lid member using a hot melt resin as a sealant is heat-sealed.

[0003]

However, a conventional paper container using a lid material made of a hot-melt resin as a sealant has an excessively strong opening force and is difficult to open, and often covers the surface of the paper container at the time of opening. Destruction occurs between the paper and the polyethylene covering the surface without destruction between the polyethylene and the hot melt resin of the lid material, and the peeling appearance is poor. Even when breakage occurred between them, the peeled surface became stringy and the appearance was poor. In addition, since the heat resistance is insufficient, the lid may be opened during the transportation of summer noodles, particularly in the use of instant noodles. As a solution to these problems, the present inventors have already disclosed in Japanese Patent Application Laid-Open No. 10-337829.
Japanese Patent Application Laid-Open No. 11-58642 and Japanese Patent Application Laid-Open No. H11-58642, it has been found that users are demanding further improvements in peeling appearance and heat resistance.

[0004] That is, Japanese Patent Application Laid-Open No. 10-337829 discloses a low-density polyethylene with polybutene-1 added thereto.
In some cases, the sealing layer containing No. 1 was cohesively broken, and at this time, the low-density polyethylene was stretched to cause stringing, which was sometimes pointed out as poor appearance. Also, Japanese Patent Application Laid-Open No. 11-58642
Japanese Patent Application Publication No. JP-A-2003-133873 discloses a low-density polyethylene and polybutene-1 to which ethylene-α-olefin copolymer rubber is added to improve stringing at the time of opening. In some cases, it was pointed out that heat resistance was insufficient due to the use of α-olefin copolymer rubber.

The present invention has been made in view of the background of the prior art.
It is an object of the present invention to provide an easily-openable composite film and an easily-openable polyethylene container which are hardly softened by heat, have good peeling appearance and heat resistance, and are excellent in openability and sealability.

[0006]

The present invention employs the following means in order to solve the above-mentioned problems. That is, the easy-opening composite film of the present invention is a composite film in which a seal layer (layer A) and a base material layer (layer B) are laminated, and the layer A has a melt flow rate of 2 to 2.
30 g of low density polyethylene a in the range of 0 g / 10 min.
5wt% and melt flow rate 50-300g / 1
10% to 40% by weight of low density polyethylene b in the range of 0 minutes
And polybutene-1 in a layer composed of 10 to 40 wt%, and the layer B is constituted of a layer composed of a polyethylene resin.

Further, the easy-open polyethylene container of the present invention comprises a lid member using the A layer surface of the easy-open composite film as a sealant layer, and a polyethylene container, and the A layer surface of the lid member. Are sealed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is based on the above-mentioned subject matter, that is, an easy-opening composite film having good peeling appearance and heat resistance and excellent in opening property and sealing property. As the A layer of the composite film in which the and the base layer (B layer) are laminated, a specific resin composition comprising a specific low-density polyethylene a, a specific low-density polyethylene b, and polybutene-1 is used. As a result, it was determined that such a problem could be solved at once.

That is, the present invention is a laminated composite film in which the thickness of the seal layer and the base material layer is in a specific range, wherein the base material layer is a layer made of a polyethylene resin, and the seal layer is formed of a film. By adding polybutene-1 for controlling the sealing strength to low-density polyethylene having a viscosity in the range of possible, and further mixing extremely low-viscosity crystalline low-density polyethylene at the above specific ratio,
The low-density polyethylene in the seal layer, which cohesively breaks when opened, is easy to cut without extending, so that stringing does not occur.Since all resins used in the composite film are made of crystalline resin, softening due to heat is less likely to occur. The point that an easily openable composite film having a good peel appearance and a good heat resistance was provided by an industrially easy method, and the composite film was used for a lid material of a polyethylene container, and the peel appearance was good. The present invention is characterized in that an easy-open polyethylene container having good heat resistance and good openability can be provided.

First, the layer A, which is the seal layer of the easy-open composite film of the present invention, has a melt flow rate of 2 to 20 g.
30 to 75 watts of low density polyethylene a in the range of / 10 min
%, The low-density polyethylene b having a melt flow rate in the range of 50 to 300 g / 10 minutes needs to be 10 to 40 wt%, and the polybutene-1 needs to be 10 to 40 wt%.

The low-density polyethylene a used for the sealing layer (layer A) is a high-pressure low-density polyethylene, a linear low-density polyethylene using a single-site catalyst, or a mixture of both. It is necessary that the flow rate be in the range of 2 to 20 g / 10 minutes. If it is less than 2 g / 10 minutes, the fluidity at the time of melting is poor, and it is not possible to fill the step of the overlapping portion of the flange portion of the polyethylene container, and if it exceeds 20 g / 10 minutes, stable film formation becomes difficult.

The linear low-density polyethylene using a single-site catalyst is obtained by copolymerizing ethylene monomer as a main component with butene-1, hexene-1, octene-1, and the like.

The low-density polyethylene may have some other components copolymerized within a range not to impair the object of the present invention.

It is necessary that the mixing ratio of the low-density polyethylene a to the layer A is 30% by weight to 75% by weight.
If the ratio of the polyethylene is less than 30% by weight, the sealing strength with the paper container is low and the sealing property cannot be satisfied. If it exceeds 75% by weight, the sealing strength becomes too strong and the opening property is satisfied. Can not.

The low-density polyethylene a has a melting point of 80.degree.
115 ° C. is preferable, and 90 to 110 ° C. is particularly preferable.
If the melting point is less than 80 ° C., the film may cause difficulty in handling due to blocking, and when the polyethylene container having the film as a cover material is left in a high temperature place such as in a car in summer, In some cases, there may be a distribution problem such as a risk that the lid may come off. on the other hand,
If the melting point exceeds 115 ° C., it is not possible to fill the step of the overlapping portion of the flange portion of the polyethylene container at the time of sealing, resulting in poor sealing performance. Further, the polyethylene container of the present invention includes a paper container in which the surface of the container is coated with a polyethylene resin. In such a container, when the melting point of the low-density polyethylene a exceeds 115 ° C., In this case, there is a problem that moisture contained in the paper of the container foams, resulting in a poor appearance.

The low-density polyethylene b used for the sealing layer (layer A) has a melt flow rate of 50 to 300 g / 10
Min, preferably in the range of 150 to 250 g / 10 min. If the melt flow rate of the polyethylene is 50 g / 10 minutes or less, the effect of improving stringiness at the time of opening is low, and if it exceeds 300 g / 10 minutes, stable film formation becomes difficult.

The compounding ratio of the low-density polyethylene b is 10
It must be in the range of wt% to 40 wt%. When the ratio of the polyethylene is less than 10% by weight, the effect of improving stringing at the time of opening is low, and when it exceeds 30% by weight, it is difficult to form a film stably.

Polybutene which is another component used in the layer A is
Reference numeral 1 denotes a polymer of butene-1 and a polymer obtained by copolymerizing ethylene or propylene with butene-1 as a main component, and the blending ratio is required to be in the range of 10 wt% to 40 wt%. If the compounding ratio is less than 10 wt%, the sealing strength becomes too strong, and the opening property cannot be satisfied. If it exceeds 40% by weight, the sealing strength is low and the sealing property cannot be satisfied.

The polybutene-1 has a melting point of 70 ° C. to 125 ° C.
C., the melt flow rate is preferably 1 to 30 g / 10 min. If the melting point is lower than 70 ° C., the film may be blocked and handling may be difficult. On the other hand, if the melting point is higher than 125 ° C., it is necessary to seal at a high temperature, and the moisture contained in the paper of the container foams and the appearance is poor. May occur. The melt flow rate is 1 g / 10 m
If it is less than 30%, mixing with polyethylene becomes difficult,
If it exceeds g / 10 min, it may be difficult to form a stable film.

The layer B needs to be made of a polyethylene resin. The reason is that when heat-sealed to the container, it melts together with the layer A and fills in the steps of the overlapping portion of the flange portion of the paper container, and has sufficient adhesive strength with the layer A as a base material layer (the This is because the adhesive strength must be larger than the cohesive failure force), and a role to withstand handling during film formation and processing steps.

Here, the polyethylene-based resin is a resin selected from high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, modified products thereof, and mixtures thereof. It is preferable to select a polyethylene resin having a melting point higher than that of the low-density polyethylene used for the A layer. If the melting point of the polyethylene resin as the main component of the layer B is lower than the melting point of the low-density polyethylene used for the layer A, the step of the overlapping portion of the flange portion of the paper container may not be filled. A particularly preferred example of the B layer resin is a mixed composition of low density polyethylene and high density polyethylene. In this case, the film has appropriate rigidity and is excellent in handleability.

In the layer B, specific additives, specifically erucamide or behenic amide, are added to the layer B so as to ensure slipperiness and lamination suitability suitable for film processing within a range not to impair the object of the present invention. Organic lubricant such as 500, molecular weight 500
The above antioxidants and organic particles such as silica, zeolite, calcium carbonate and polymethyl methacrylate crosslinked particles may be selected and used. Further, as long as the effect of the present invention is not impaired, ears and slit dust generated when producing the film of the present invention can be mixed and used with the B layer polymer as needed.

The thickness of the layer A is preferably 3 μm or more, more preferably 5 μm or more. 3 μm thick
If the ratio is less than the above, it is difficult to fill the step in the overlapping portion of the flange portion of the paper container at the time of sealing, and there is a possibility that the sealing performance may be poor. The thickness ratio of the layer A in the composite film is preferably from 10 to 50%, and particularly preferably from 20 to 40%. A layer thickness ratio is 1
If it is less than 0%, if the sealing pressure is too strong, the base layer may partially adhere to the polyethylene of the polyethylene container, resulting in poor openability, while the thickness ratio exceeds 50%. In this case, the sealing layer made of the incompatible component has poorer flow stability at the time of melting than the base layer, so that the film forming stability is deteriorated.

The thickness of the composite film may be determined according to the size of the step at the overlapping portion of the polyethylene container, but is preferably in the range of 25 to 100 μm. If it is less than 25 μm, the step may not be filled, and if it exceeds 100 μm, the cost increases and the economy is poor.

The composite film of the present invention has two layers, A layer and B layer.
Although it is a composite film composed of layers, the third and fourth layers may be laminated on the layer B side, which is a base material layer, if necessary, to form a laminated film of three or more layers.

The method for producing the easy-opening composite film of the present invention is not particularly limited, but the polymers of the A and B layers are melted and extruded using two extruders, respectively, and the pipe is formed by a pinol or feed block method. A method of laminating in a molten state by a method such as a composite or coextrusion multilayer die method is efficient.
The film thus formed can be subjected to a surface treatment, if necessary, to improve the adhesiveness during lamination. This surface treatment method is corona discharge treatment,
Plasma treatment, flame treatment and the like are employed.

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of an easily-openable composite film of the present invention, in which one side is an A layer 1 and the back side is a B layer. This easy-opening composite film is punched to form a lid material. The polyethylene container referred to in the present invention includes not only a container formed of polyethylene resin alone, but also a laminated product of polyethylene resin and paper, particularly a paper container whose surface is coated with polyethylene resin. It is. That is, the cover material 5 is composed of the lid material 5 using the layer A surface of the above-mentioned easy-opening composite film as a sealant layer, and the polyethylene container 6, and the layer A surface of the lid material 5 is sealed. is there. That is, the lower container portion of the container is made of polyethylene resin, or is made of paper having a polyethylene resin layer on at least one surface. The layer A of the above-mentioned easy-opening composite film of the present invention has the above-mentioned effects, that is, excellent easy-opening properties and excellent appearance after peeling, with respect to the polyethylene resin.

The polyethylene container of the present invention will be described with reference to a paper container in which a polyethylene resin is laminated on one side. As shown in FIG. 2, the container portion 6 of the container is made of paper 4 'whose inner surface is coated with a polyethylene resin 4, and the flange portion 3 of the container (a portion that seals with the lid member 5). ) Have a step (not shown) at the overlapping portion of the paper.

As the polyethylene resin 4, a resin selected from high-pressure low-density polyethylene, linear low-density polyethylene, modified products thereof, and mixtures thereof can be used. Is preferably used. The method of coating the paper 4 'with the polyethylene resin 4 is not particularly limited, such as an extrusion laminating method, a dry laminating method, and a coating method. Preferably, an extrusion laminating method having good productivity is employed.

The cover material 5 used here is provided on the B layer 2 side of the easily-openable composite film shown in FIG. 1 on a reinforcing substrate such as an aluminum foil, a stretched polyethylene terephthalate film, a stretched nylon film, a stretched polypropylene film, or paper. Laminates 2 'may be used alone or in combination as needed, but there is no particular limitation on the reinforcing substrate 2' laminated on the B layer 2 side.

The lid 5 formed of the composite film of the present invention is heat-sealed to the paper container at the flange portion 3 by a conventional method to produce an easily-openable paper container. The cross section is shown in FIG. The container 6 in this figure is made of a paper material 4 ′ obtained by laminating a polyethylene resin 4 on the inner surface.
The lid member 5 is composed of an easily openable composite film in which one surface is an A layer 1 and a stretched polyethylene film 2 'as a reinforcing base material is laminated on the A layer 1 surface. The container is formed by heat-sealing the A layer 1 of the lid member 5 and the polyethylene resin layer 4 of the container part 6 with the flange part 3.

Next, an example of the method for producing the easily-openable composite film of the present invention will be described. Using two extruders, 50 wt% of low density polyethylene a, 30 wt% of low density polyethylene b, and 2 wt% of polybutene-1 were obtained from one extruder.
0 wt% mixed resin is melted at 180-250 ° C and extruded (layer A). Another extruder melts low-density polyethylene 50wt% and high-density polyethylene 50wt% mixed resin at 180-250 ° C. And extrude (B
Layer), laminated with a pipe composite or a co-extruded multilayer die, extruded from the die into a film so that the thickness of layer A is 5 μm or more, cast and cooled with a cooling roll at 25 to 60 ° C., and solidified to form a composite film. Subsequently, if necessary, the surface of the layer B is subjected to a corona discharge treatment, wound up, and further, a predetermined width,
By slitting to the length, the easily openable composite film of the present invention can be obtained.

Such an easy-opening composite film is particularly preferably used as a sealant film (A layer 1) for a lid member 5 of a paper container in which the surface of the container is coated with a polyethylene resin 4, and for a polyethylene container. It can also be suitably used as an easily-openable sealant film described above, as well as a bag-made product (a product in which the layer A and the layer A are sealed as the inner surface of the bag) using the easily-openable composite film as a sealant film.

The easily openable polyethylene container of the present invention can be suitably used as a container for dairy products such as yogurt, natto, instant noodles and the like.

[0036]

EXAMPLES The present invention will be described based on examples, but the present invention is not limited to these examples.

The method for measuring the characteristics and the method for evaluating the effects in the examples are as follows.

(1) Crystal melting point (Tm) Using a scanning finger calorimeter (abbreviation: DSC), set a 3 mg sample, measure at a heating rate of 10 ° C./min from room temperature, and melt the crystal. Is measured, and the peak temperature (° C.) is taken as the crystal melting point. At this time, when a plurality of melting peaks are observed, the maximum peak temperature is defined as Tm.

(2) Melt flow rate (MFR) JIS K-7210 Sample conditions were (190 ° C., 2.16
Kgf).

(3) Heat seal strength, openability Laminated 80 μm low-density polyethylene on one side of a 250 μm thick paper laminated on the polyethylene side of a 330 μm total thickness paper base with a 12 μm thick stretched polyethylene terephthalate film The A layer side of the test composite film was placed on top, and the lower plate (paper substrate side) of the seal bar of the flat plate heat sealer was set to 80 ° C, and the upper plate (test composite film side) was set to 150 ° C and heat-sealed. Create a sample for Next, the peel strength was measured using an Instron to determine the heat seal strength.

In the case where the heat sealing strength was too strong and breakage occurred between the paper and the coated polyethylene, it was judged as poor sealing (x). On the other hand, those having a size of less than 5 N / 15 mm did not reach the sealing strength required for the lid material, and thus were judged to be defective in sealing (x).

The openability is such that the heat seal strength is 10 to 19
Those with N / 15 mm were evaluated as good (○), and others were evaluated as poor (x).

(4) Evaluation of sealing performance (Evaluation of the degree of burying of the step in the overlapping portion of the paper container) A 12 μm-thick portion was superimposed on the step portion where the paper substrate having a total thickness of 330 μm in the above item (3) was overlapped. The layer A side of the test composite film laminated with the stretched polyethylene terephthalate film is overlapped and heat-sealed under the same conditions as in (3) to prepare a sample for measurement.
Next, a drop of a saturated solution of the dye Eosin Y in ethanol was dropped on the sealed step, and the liquid that passed through the step was poor in sealing performance (x). The sealability was judged to be good (（).

(5) Evaluation of heat resistance A heat-sealed paper container was placed in an oven at 80 ° C., and a cover opened due to an increase in internal pressure was judged as (X), and a cover not opened was judged as (O). did.

(6) Evaluation of Appearance of Peeling When a paper container heat-sealed was peeled off, when no stringing was visually observed (◎), small threading was seen during peeling but no trace was left. Those with a string remaining about 1 mm were judged as (○), and those with a string longer than 1 mm remained as (X). Examples 1, 2, 3 Using two extruders, MFR7.
0, low density polyethylene (LDPE) a having a density of 0.918 and a melting point of 106 ° C. and MFR200, low density polyethylene (LDPE) b having a density of 0.919 and a melting point of 106 ° C. and MFR20 and polybutene-1 (PB-) having a melting point of 123 ° C.
1) were mixed in the ratio shown in Table 1, melted at a temperature of 220 ° C. and extruded (layer A), and MFR was extruded from another extruder.
7.0 wt% of low density polyethylene (LDPE) having a density of 0.920 and a melting point of 109 ° C. and 50 wt% of MFR 8.0, density of 0.960 and high density polyethylene having a melting point of 132 ° C.
t%, melt at a temperature of 240 ° C. and extrude (B
Layer), laminated with a co-extrusion die and extruded into a film.
Cooled and solidified with a cooling roll at 5 ° C, and the thickness of layer A was 10μ.
A composite film having a total thickness of 40 μm, in which the thickness of the m and B layers was 30 μm, was obtained.

As shown in Table 1, the obtained composite film had good peeling appearance, excellent heat resistance, adequate sealing strength, and good openability and sealability. Comparative Examples 1 and 2 As shown in Table 1, a composite film was obtained under exactly the same conditions as in Example 1 except that the mixing ratio of low-density polyethylene (LDPE) b in the sealing layer was out of the range of the present invention. Was.

In Comparative Example 1, low-density polyethylene (LDP)
E) Since the amount of b is too small, small stringing occurs at the time of opening, and the peeling appearance is at a usable level, but Comparative Example 2 in which low density polyethylene (LDPE) b is not added.
Had a noticeable stringiness and a poor appearance. Examples 4 and 5 In Examples 4 and 5, composite films were obtained under exactly the same conditions as in Example 1 except that the polybutene-1 of the sealing layer was mixed at the ratio shown in Table 1.

As shown in Table 1, the obtained composite film had good peeling appearance, excellent heat resistance, suitable sealing strength, and good openability and sealability. Comparative Examples 3 and 4 In Comparative Examples 3 and 4, composite films were obtained under the same conditions as in Example 1 except that the concentration of polybutene-1 in the sealing layer was changed as shown in Table 1.

In Comparative Example 3, since the amount of polybutene-1 was too small, the sealing strength was too strong, and peeled between the paper container and the polyethylene covering the surface upon opening, and the appearance was poor. In Comparative Example 4, since the polybutene-1 was too large and the sealing strength was low, the sealing property was poor, and in a heat resistance test in an oven at 80 ° C., it was not able to withstand an increase in the internal pressure, and the seal was missing. Comparative Example 5 In Comparative Example 5, low-density polyethylene (LDP)
E) Ethylene propylene pyrene rubber (EPR) instead of b
Was obtained under the same conditions as in Example 1 except that was added as a release appearance improving agent.

The film of Comparative Example 5 had good peeling appearance and good sealing performance at room temperature, but had poor heat resistance.
In an oven at a temperature of ° C., it was not able to withstand the rise of the internal pressure, and the seals came off. Examples 6 and 7 In Example 6, a low-density polyethylene (L) having a MFR of 7.0, a density of 0.920, and a melting point of 109 ° C.
A composite film was obtained under the same conditions as in Example 1 except that DPE was 100%.

In the seventh embodiment, the B layer is formed by the MF shown in the first embodiment.
Example 1 except that R8.0, density 0.960, and melting point 132 ° C. were 100% of high-density polyethylene (HDPE).
Under the same conditions as above, a composite film was obtained.

As shown in Table 1, all of Examples 6 and 7 had good peeling appearance, excellent heat resistance, proper sealing strength, and good openability and sealability. Example 8 In Example 8, the thickness of the layer A was 5 μm, and the thickness of the layer b was 3 μm.
A composite film was obtained under the same conditions as in Example 2 except that the thickness was changed to 5 μm. As shown in Table 1, this composite film had good peeling appearance and heat resistance, had an appropriate seal strength, and had good openability and sealability. Example 9 In Example 9, the thickness of the layer A was 3 μm, and the thickness of the layer B was 3 μm.
A composite film was obtained under the same conditions as in Example 2 except that the thickness was changed to 7 μm. This composite film had good peeling appearance and heat resistance, and good openability and sealability, although there was some variation in seal strength.

[0053]

[Table 1]

[0054]

According to the present invention, it is possible to provide an easily-openable polyethylene container which is excellent in peeling appearance and heat resistance, has good openability, and has no problem of hermeticity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an easily-openable composite film of the present invention.

FIG. 2 is a cross-sectional view showing an example of an easily-openable polyethylene container according to the present invention.

[Description of Signs] 1: Layer A (seal layer) 2: Layer B (base layer) 2 ′: Reinforcement base 3: Flange 4: Polyethylene resin (base part base) 4 ′: Paper material 5: Lid 6: Container

 ──────────────────────────────────────────────────の Continuing on the front page F term (reference) 3E067 AB01 AC01 BA07A BA15A BB15A BB25A BC03A BC07A CA17 EA06 EA12 EA29 FA01 FC01 GD08 3E084 AA06 AA24 BA01 CA01 CC04 FD13 GB08 LA07 LB02 4F100 AK04A AK05A05A05A06A05B05 BA10B BA16 DA01 EH20 GB15 GB16 GB18 JA06B JA20B JJ03 JL12B JL14 YY00B

Claims (5)

[Claims] 1. A composite film in which a seal layer (A layer) and a base material layer (B layer) are laminated, wherein the A layer has a low density having a melt flow rate of 2 to 20 g / 10 minutes. Low density polyethylene b having a polyethylene a content of 30 to 75 wt% and a melt flow rate of 50 to 300 g / 10 min.
Is 10 to 40 wt%, and polybutene-1 is 10 to 40 w
%, wherein the layer B is composed of a layer made of a polyethylene resin. 2. The easy-opening composite film according to claim 1, wherein the thickness of the layer A is 3 μm or more. 3. The easy-opening composite film according to claim 1, wherein the thickness of the layer A is 5 μm or more. 4. The easy-open composite film according to claim 1, wherein the low-density polyethylene b has a melt flow rate in a range of 150 to 250 g / 10 minutes. 5. A lid material using the A layer surface of the easily-openable composite film according to any one of claims 1 to 4 as a sealant layer, and a polyethylene container, and the A layer surface of the lid material is An easily-openable polyethylene container, which is configured to be sealed.