JP2024020755A - Laminate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film which can be easily opened without causing lid tearing or the like when opened as a lid member when used as a lid material for a container or the like.

SOLUTION: There is provided a laminate film having a heat seal layer and at least one or more support layers, wherein for elongation at break A1 and breaking strength B1 before heat sealing and elongation at break A2 and breaking strength B2 after heat sealing overlap with a polyethylene terephthalate film at a seal temperature of 200°C, a seal pressure of 0.2 MPa and a sealing time of 1 second, followed by peeling off the polyethylene terephthalate film, A1/A2 is 2.5 or less and B1/B2 is 3.0 or less in both a longitudinal direction and a width direction.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a laminated film having excellent unsealability.

The original purpose of a package is to protect the contents, and it is important that the package resists external forces during transportation and display and is not easily opened. On the other hand, it is required to be easy to open so that the lid does not tear during use and can be opened normally and easily.

Particularly in recent years, with the increase in the elderly population and the trend towards individual eating, there has been an increasing demand for convenient and easy-to-open packages. Various types of easy-to-open packaging have been proposed, and a packaging called easy-peel uses a sealant film that makes it easy to open. It is widely used in lids for cup containers for delicatessen dishes, and in packs for processed meat products such as ham and bacon.

In order to improve the ease of opening of a sealant film, a coextruded multilayer film consisting of a heat-sealing layer made of a mixture of polypropylene resin and polyethylene resin in a specific ratio has been proposed. (For example, see Patent Documents 1 and 2)
However, even when the coextruded multilayer film proposed in Patent Documents 1 and 2 is used as a sealant film, if the sealing conditions change, the opening strength becomes strong and the seal cannot be opened with appropriate force. There was a problem with the lid tearing during opening.

JP 2021-95162 Publication JP2019-209541A

An object of the present invention is to provide a laminated film that can be easily punched out as a lid material, does not cause lid tearing, etc., and can be easily opened when used as a lid material for a container.

In order to solve the above problems, the present invention is as follows.

A laminated film having a heat sealing layer and at least one support layer, which has a breaking elongation A1 and a breaking strength B1 before heat sealing, and has a sealing temperature of 200°C and a sealing pressure of 0.2 MPa when stacked with a polyethylene terephthalate film. , after heat sealing with a sealing time of 1 second and peeling off the polyethylene terephthalate film, regarding the breaking elongation A2 and breaking strength B2, A1/A2 is 2.5 or less in both the longitudinal direction and the width direction, B1/ The laminated film has a B2 of 3.0 or less.

The laminated film of the present invention can be used as a lid material and can be opened normally without causing the lid to tear when opened, and can be easily opened with an appropriate amount of force. Furthermore, by laminating at least one layer selected from biaxially oriented polyamide film, biaxially oriented polyester film, printed paper, metal foil, etc. on the support layer side of the laminated film, the lid material will not tear when opened. A package that can be opened normally can be obtained.

The laminated film of the present invention will be specifically explained.

The laminated film of the present invention is a laminated film having a heat-sealable heat-sealable layer and one or more supporting layers, the heat-sealing layer having easy-to-open properties and laminated with at least one or more supporting layers. As a result, the lid can be opened normally without causing the lid to tear when opened.
The laminated film of the present invention has good film formability even when the support layer is one layer, and can be opened normally without causing the lid to tear when opened. It is possible to improve film-forming properties such as increasing the film-forming speed, and to suppress tearing of the lid when the support layer 2 is used as a lid material.

The laminated film of the present invention is a laminated film having a heat-sealing layer and at least one support layer, and the laminated film has a breaking elongation A1 and a breaking strength B1 before heat-sealing, and is heat-sealed at 200°C for 1 second. Regarding the breaking elongation A2 and breaking strength B2 after sealing, A1/A2 is 2.5 or less and B1/B2 is 3.0 or less in both the longitudinal direction and the width direction of the laminated film, preferably A1/A2. is 2.3 or less, and B1/B2 is 2.8 or less, both of which have a lower limit of 1.0.

In the laminated film of the present invention, by setting A1/A2 to 2.5 or less in both the film longitudinal direction and the width direction, the flexibility of the film is increased and lid tearing does not occur when opening the film. By setting B1/B2 to 3.0 or less in both the longitudinal direction and the width direction of the film, wrinkles do not occur during winding during film formation, and film formability is improved.

The laminated film of the present invention preferably has a heat sealing strength of 10 N/15 mm or more, more preferably 12 N/15 mm or more when the heat sealing layer of the laminated film is heat sealed with a polypropylene sheet at 140°C for 1 second. . By heat-sealing strength of 10N/15mm or more when heat-sealing with a polypropylene sheet at 140°C for 1 second, the heat-sealing property is better over a wide temperature range from the low heat-sealing temperature of 140°C, and packaging This is preferable because it improves workability during production of the material and filling of the packaging material.

The heat sealing strength of the heat sealing layer of the laminated film of the present invention when heat sealing with a polypropylene sheet at 180°C for 4 seconds and when heat sealing for 1 second is both in the range of 20 N/15 mm or more and 28 N/15 mm or less. , the difference therebetween is preferably 3.5N/15mm or less.

The above heat sealing strength at 140℃ for 1 second is 10N/15mm or more, and the heat sealing strength at 180℃ for 4 seconds and 1 second is both within the range of 20N/15mm or more and 28N/15mm or less, and the difference between them By setting it to 3.5N/15mm or less, the sealing temperature dependence is small, the heat sealability is better in a wide temperature range, and the workability when manufacturing packaging materials and filling contents into packaging materials is higher. Become.

The heat-sealing layer of the laminated film of the present invention is preferably made of a resin composition that is a mixture of polyethylene resin and polypropylene resin, and further contains 51% to 80% by mass of polyethylene resin and 20% by mass of polypropylene resin. % to 49% by mass is preferable because the sealing temperature dependence is small and the heat sealability is good over a wide temperature range.

Examples of the polyethylene resin include at least one of high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and ethylene/α-olefin random copolymer elastomer. Among these, a mixed resin composition of linear low density polyethylene and an ethylene/α-olefin random copolymer elastomer is preferred.

The above linear low density polyethylene has a density of 0.910 to 0.940 g/cm ³ and a melt flow rate (hereinafter sometimes abbreviated as MFR) of 1.0 to 40.0 g/10 minutes at 190°C. Preferably, the ethylene/α-olefin random copolymer elastomer has a density of 0.865 to 0.895 g/cm ³ and an MFR of 0.5 to 10.0 g/10 min at 190°C. However, each of them has good miscibility and is preferable.

The polypropylene resin of the heat-sealing layer is preferably an ethylene/propylene random copolymer of propylene and a comonomer, and the comonomers include ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-octene. -decene, etc., and those containing less than 5% by mass of comonomers are preferred.

The above polypropylene resin contains a polypropylene resin polymerized using a single site catalyst (metallocene catalyst), etc., so that it has good miscibility with the above polyethylene resin, has low sealing temperature dependence, and can be sealed from low temperatures. It is preferable because it has good heat sealability over a wide temperature range.

Polypropylene resins polymerized using single-site catalysts may have narrower molecular weight distributions, narrower composition distributions, and fewer low-order components than those polymerized using multi-site catalysts (Ziegler-Natta catalysts). Therefore, it may have excellent low-temperature sealing properties, high rigidity, high tensile strength, and high impact resistance.

The type of single-site catalyst is not particularly limited, but a typical example is a metallocene catalyst. The production of metallocene polypropylene generally requires (i) a transition metal compound of Group 4 of the periodic table (so-called metallocene compound) containing a ligand having a cyclopentadienyl skeleton, and (ii) a metallocene compound and a metallocene compound. An example is the use of a co-catalyst that can be activated into a stable ionic state. This co-catalyst may be subjected to a reaction treatment with an organic aluminum compound or the like, if necessary. The metallocene compound is preferably a crosslinked metallocene compound that enables polymerization with stereoregularity of propylene, and more preferably a crosslinked metallocene compound that enables polymerization with isotactic regularity of propylene.

The method for producing polypropylene resin produced using a single-site catalyst is not particularly limited, and known slurry polymerization methods, bulk polymerization methods, gas phase polymerization methods, etc. can be used. It is also possible to manufacture using a multi-stage polymerization method.

The melting point of the polypropylene resin produced using a single-site catalyst is preferably 120 to 160°C, more preferably 140°C or lower, and more preferably the Vicat softening temperature is 100 to 135°C. can be heat-sealed, resulting in a better film.

The density of the polypropylene resin is preferably 0.87 to 0.93 g/cm ³ and the MFR is preferably in the range of 1 to 30 g/min at 230°C. In this case, the film forming property is good and the heat sealing strength is also suitable. .

As mentioned above, the resin composition of the heat-sealing layer is preferably composed of a mixture of 51 to 80% by mass of polyethylene resin and 20% to 49% by mass of polypropylene resin, and is suitable for use as a container lid material. When used, the heat-sealing layer undergoes cohesive failure, and the heat-sealing strength is in the range of 10-28N/15mm at a heat-sealing temperature range of 140°C to 180°C, and there is no stringiness when opening, making it easier to open. A good film is obtained.

The support layer of the laminated film of the present invention preferably contains 50% by mass or more of linear low-density polyethylene. If the above-mentioned linear low-density polyethylene is less than 50% by mass, the flexibility of the laminated film may decrease, the film may tear when opened, and the seal may not be opened properly when used as a container lid. . When there are two or more supporting layers, it is preferable that each supporting layer contains 50% by mass or more of linear low-density polyethylene.

The above-mentioned linear low density polyethylene may be obtained using a single site catalyst method or a multisite catalyst method, and the comonomers include 1-butene, 1-hexene, 4-methyl-1-pentene. , 1-octene. Linear low-density polyethylene may have a higher melting point (Tm) than high-pressure low-density polyethylene, improve the heat resistance of the film, and have excellent cold resistance, so it may have stronger lid tear resistance. The density is preferably in the range of 0.905 to 0.95 g/cm ³ , more preferably in the range of 0.910 to 0.940 g/cm ³ . The MFR at 190° C. is preferably in the range of 0.5 to 100 g/10 minutes, more preferably in the range of 1 to 20 g/10 minutes.

Resins other than linear low-density polyethylene for the support layer include high-pressure low-density polyethylene, high-density polyethylene, ethylene/propylene random copolymer, ethylene/propylene block copolymer, and ethylene-α-olefin random copolymer. It is preferable to use at least one kind selected from coalesced elastomers because it has good dispersibility in linear low-density polyethylene.

In order to ensure slipperiness and lamination suitability suitable for film processing, specific additives such as erucic acid amide are added to the support layer and heat seal layer in the present invention, within a range that does not impair the purpose of the present invention. Organic lubricants, antioxidants with a molecular weight of 500 or more, inorganic particles such as silica, zeolite, and calcium carbonate, and organic particles such as crosslinked polymethyl methacrylate particles may be selected and used. Further, it may contain an antioxidant, a heat stabilizer, an antistatic agent, etc., which improve film forming properties. If necessary, selvage and slit waste generated during production of the laminated film of the present invention may be mixed into the support layer as long as it does not impede the effects of the present invention.

For the support layer and heat-sealing layer in the present invention, a plant-derived polyethylene resin or a plant-derived polypropylene resin (hereinafter also referred to as biomass resin) may be selected and used for the purpose of reducing environmental impact. good. At this time, the index expressing the proportion (mass%) of plant-derived raw materials in the total composition is called biomass degree, which is contained in a certain concentration in plant-derived raw materials, and is almost absent in petroleum-derived raw materials. By measuring the concentration of radioactive carbon (C ¹⁴ ) by accelerator mass spectrometry, the degree of biomass (%) can be calculated. However, in recent years, raw material manufacturers have provided minimum biomass values for each plant-derived raw material without accelerator mass spectrometry of the actual product. Based on the minimum biomass degree and the blending amount of each plant-derived raw material, the biomass degree, which is the ratio (%) of the plant-derived raw materials in the entire composition, can be calculated almost accurately.

Examples of plant-derived resins include polyterpene resins. Examples of polyterpene resins include α-pinene, β-pinene, dipentene, styrene-modified terpenes, and hydrogenated products thereof.

The degree of biomass when a plant-derived resin is added to the laminated film of the present invention is preferably 1% by mass or more and 45% by mass or less, more preferably 3% by mass or more and 40% by mass or less. If the biomass content is less than 1% by mass, the contribution to reducing the environmental load is low, and the higher the biomass content, the higher the contribution to reducing the environmental burden, but if it exceeds 45% by mass, the film formability may deteriorate. , the film may become brittle and processability may deteriorate.

The thickness of the laminated film of the present invention is preferably 15 to 100 μm. The thickness of the support layer is preferably in the range of 10 to 70 μm, more preferably in the range of 13 to 60 μm, which is suitable for good punchability and handling when used as a container lid material.

The thickness of the heat seal layer is suitably in the range of 1 to 30 μm, preferably 1.5 to 20 μm. If the thickness of the heat-sealing layer exceeds 30 μm, poor appearance of peeling such as stringing, feathering, or film residue may occur when peeling. If the thickness of the heat-sealing layer is less than 1 μm, stable heating may occur. Seal strength may not be obtained.

Here, stringing refers to a condition in which the film stretches like a thread and peels off when the package is opened, and feathering or film residue refers to a condition in which the film remains in the adherend container and peels off when the package is opened. To tell.

The laminated film of the present invention is used by laminating at least one other base material layer selected from polyamide film, polyester film, printing paper, and metal foil on the support layer side, either singly or in combination, as necessary. is preferable.

Examples of the polyamide film include nylon 6, nylon 11, and nylon 66, with biaxially stretched nylon 66 film being more preferred in terms of heat resistance and moisture resistance.

Examples of polyester films include biaxially oriented polyethylene terephthalate film (hereinafter sometimes abbreviated as PET), biaxially oriented polyethylene naphthalate film, and biaxially oriented polybutylene terephthalate film, among which biaxially oriented polyethylene terephthalate film Film is more preferable overall in terms of heat resistance, film cost, etc.

The thickness of the polyamide film or polyester film is preferably in the range of 5 to 100 μm, and in particular, the thickness in the range of 12 to 50 μm has good suitability for printing, and when used as a lid material, it has good lid tear resistance and punching properties. preferred.

Examples of the metal foil include aluminum foil and copper foil, and among them, aluminum foil is more preferable. The thickness of the metal foil is preferably in the range of 5 to 30 μm when used as a lid material from the viewpoint of punchability, handleability, and economy.

Examples of the printing paper include synthetic paper, high-quality paper, medium-quality paper, art paper, coated paper, and varnished paper, and art paper is preferred from the viewpoint of printing quality.

Methods for laminating other base material layers on the support layer side include, but are not particularly limited to, methods of laminating via adhesives, hot melt agents, and low melting point extrusion laminating resins.

Next, an example of the method for manufacturing the laminated film of the present invention will be explained.

Using three extruders, one extruder produces support layer 1 with a density of 0.90 to 0.97 g/cm ³ and an MFR (190°C) of 1.0 to 40.0 g/10. Extrude polyethylene resin in the range of 180 to 250°C,
From another extruder, a polyethylene resin with a density of 0.90 to 0.97 g/cm ³ and an MFR (190°C) of 1.0 to 40.0 g/10 minutes was produced as the support layer 2. Extrusion at 180-250℃,
From another extruder, a linear low density layer with a density of 0.90 to 0.94 g/cm ³ and an MFR (190°C) of 1.0 to 40.0 g/10 minutes is produced as a heat seal layer. A resin composition prepared by mixing polyethylene with an ethylene/propylene random copolymer having a density of 0.87 to 0.93 g/cm ³ and an MFR (230°C) of 1 to 40 g/min is extruded at 200 to 250°C. , and laminated with a coextrusion multilayer T-die. Here, the thickness of the support layer 1/support layer 2/heat seal layer is extruded into a film shape such that the thickness becomes 5 μm/45 μm/5 μm, and the film is cast and solidified using a cooling roll at 25 to 50°C to form a laminated film. . Subsequently, the surface of the support layer 1 is subjected to a corona discharge treatment, if necessary.

The present invention will be explained based on Examples, but the present invention is not limited thereto. The method of measuring the characteristics and the method of evaluating the effect in the present invention are as follows.

(1) Resin Density Density was measured according to the density gradient tube method specified in JIS K 7112 (1980).

(2) Thickness of the film Using a dial gauge type thickness meter (JIS B 7509 (1992), measuring point 5 mm Φ flat type), measure 10 points at 10 cm intervals in the longitudinal and width directions of the film, and calculate the average. value.

(3) Thickness of each layer A cross section of the film was cut out using a microtome, and the cross section was observed at 1000 times magnification using a digital microscope model VHX-5000 (manufactured by Keyence Corporation). The distance in the thickness direction of each layer was measured, and the thickness of each layer was calculated back from the magnification. In determining the thickness of each layer, a total of five cross-sectional photographs of five locations arbitrarily selected from different measurement fields were used, and the average value thereof was calculated.

(4) Melt flow rate (MFR)
According to JIS K 7210 (1999), polyethylene resin was measured at 190°C, and polypropylene resin was measured at 230°C.

(5) Composite film for sealing A composite film for sealing was prepared by dry laminating PET with a thickness of 12 μm at a coating amount of 2 g/m ² using a polyurethane adhesive on the support layer side of the laminated film and aging it at 40°C for 72 hours. It was made into a film.

(6) Polypropylene sheet for evaluation (adherent)
Homopolypropylene (PP-3 described below) resin is melted from an extruder at a temperature of 220 to 230°C, extruded from a die into a film, and cast with a cooling roll at 25 to 50°C to cool and solidify, producing polypropylene with a thickness of 300 μm for evaluation. I created a sheet.

(7) Film breaking elongation and breaking strength before heat sealing and after sealing at 200°C The breaking elongation and breaking strength of the laminated film before heat sealing were measured at room temperature at 23°C using Tensilon (RTC-1210A manufactured by Orientech Co., Ltd.). ) at a tensile speed of 1000 mm/min, and other measurements were made in accordance with JIS K 7127.

The breaking elongation and breaking strength of the film after sealing at 200°C were determined by laminating 12 μm thick PET (“Lumirror (registered trademark)” P60 manufactured by Toray Industries, Ltd.) on both sides of the laminated film, and using a flat plate heat treatment manufactured by Tester Sangyo Co., Ltd. Using a seal tester (TP-701B), heat treatment was performed by heating one side from the support layer side under the conditions of a sealing temperature of 200°C, a sealing pressure of 0.2 MPa, and a sealing time of 1 second. After that, the stacked PET with a thickness of 12 μm was heat-treated. For the parts that were peeled off at room temperature of 23°C and heat treated, the tensile speed was 1000 mm/min using Tensilon (RTC-1210A) manufactured by Orientec Co., Ltd. at room temperature of 23°C, and other parts were in accordance with JIS K 7127. and measured.

(8) Method for creating a composite film for sealing A sample of PET with a thickness of 12 μm was dry laminated on the support layer side of the laminated film with a polyurethane adhesive at a coating amount of 2 g/m ² and aged at 40°C for 72 hours. It was made into a film.

(9) Heat sealing strength The composite film for sealing made in (8) was cut out to 100 mm x 15 mm, and the heat sealing layer and the 300 μm evaluation polypropylene sheet made in (6) were stacked on top of each other, and a flat plate made by Tester Sangyo Co., Ltd. Using a seal tester (TP-701B), heat-seal the sample by heating one side from the PET side at a sealing temperature of 140°C, a sealing pressure of 0.2 MPa, and a sealing time of 1 second. The heat seal strength was measured when peeled at 180° at a tensile speed of 300 mm/min using Tensilon (RTC-1210A) manufactured by Co., Ltd. At that time, take the average value of 10 measured values for each sample, and those with a value of 10N/15mm or more are marked as ○ for good low-temperature sealing properties, sealing properties, and peelability, and those with less than 10N/15mm are marked as ○. It was set as ×.

(10) Dependence of heat seal strength on seconds Using a flat plate seal tester (TP-701B) manufactured by Co., Ltd., heat-seal the sample by heating one side from the PET side at a sealing temperature of 180°C, a sealing pressure of 0.2 MPa, and a sealing time of 1 second and 4 seconds at 23°C at room temperature. Below, the heat seal strength was measured when peeled at 180° using Tensilon (RTC-1210A) manufactured by Orientech Co., Ltd. at a tensile speed of 300 mm/min. At that time, take the average value of 10 measured values for one sample, and determine the sealing performance if the difference between the sealing time of 1 second and 4 seconds is 3.5N/15mm or less in the range of 20 to 28N/15mm. Good peelability and high workability during production of the packaging material and filling of contents into the packaging material were rated as ○, and those outside of this range were rated as ×.

(11) Peeled Appearance When the heat seal strength measurement sample prepared in (9) was peeled off by hand, the peeled appearance was visually evaluated, and stringiness and film residue were determined as follows.
○: No stringiness or film residue observed. ×: Long strings of 1.5 mm or more and film residue are observed.

(12) Lid tearing property A sample of the sealing composite film prepared in (8) was cut out to 100 mm x 100 mm, and the heat seal layer and polypropylene container (95Φ x 61.9H, manufactured by Tokan Kogyo Co., Ltd.) were stacked on top of each other. A sample was heat-sealed using a hand sealer manufactured by Eishin Pack Industries Co., Ltd. at a heat-sealing temperature of 200°C, a sealing pressure of 0.3 MPa, and a sealing time of 1 second. When peeled off by hand, the composite film was A case where the composite film did not tear was marked as ○, and a case where the composite film was torn was marked as ×.

The raw materials used in this example are as follows.
(1) 1-Butene copolymerized linear low density polyethylene (LL-1)
MFR=7.0g/10min, density=0.920g/cm ³ , Tm=123°C
(2) 1-octene copolymerized linear low density polyethylene (LL-2)
MFR=2.2g/10min, density=0.921g/cm ³ , Tm=120°C
(3) High pressure low density polyethylene (LD-1)
MFR=7.0g/10min, density=0.919g/cm ³ , Tm=106°C
(4) High density polyethylene (HD-1)
MFR=8.0g/10min, density=0.961g/cm ³ , Tm=130°C
(5) Single-site catalytic ethylene/propylene random copolymer (PP-1)
MFR=7.0g/10min, density=0.900g/cm ³ , Tm=120°C
(6) Ethylene-propylene random copolymer (PP-2) using multi-site catalyst method
MFR=6.0g/10min, density=0.900g/cm ³ , Tm=145°C
(7) Ethylene-α-olefin random copolymer elastomer (E-1)
MFR=3.6g/10min, density 0.885g/ ^cm3
(8) Plant-derived polyterpene resin (PT-1)
Softening point = 115℃, biomass degree = 90%
(9) Homopolypropylene (PP-3)
MFR=8.0 g/10 min, density=0.900 g/cm ³ .

Example 1
100% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) was used as support layers 1 and 2, and ethylene-propylene random copolymer (PP-1) produced using a single-site catalyst method was used as the heat-sealing layer. Using a resin composition in which 30% by mass and 70% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) were mixed, each was charged into three extruders of three types of three-layer non-stretched film forming machines. , the support layers 1 and 2, and the heat-sealing layer were melt-kneaded at an extrusion temperature of 230°C, extruded through a 3-layer T die at 230°C, and rapidly cooled with a casting roll at 40°C to form a laminated film. Corona discharge treatment was applied to the surface. The total thickness of the obtained laminated film was 50 μm, the thickness of support layer 1 was 5 μm, the thickness of support layer 2 was 40 μm, and the thickness of the heat seal layer was 5 μm. All the properties required for the laminated film of the present invention were satisfied.

Example 2
Example 1 except that the 1-butene copolymerized linear low-density polyethylene (LL-1) in the heat seal layer of Example 1 was replaced with 1-octene copolymerized linear low-density polyethylene (LL-2). A laminated film was obtained in the same manner. All the properties required for the laminated film of the present invention were satisfied.

Example 3
35% by mass of ethylene-propylene random copolymer (PP-1), 60% by mass of 1-octene copolymerized linear low-density polyethylene (LL-2), and ethylene-α in the heat-sealing layer of Example 1. - A laminated film was obtained in the same manner as in Example 1, except that a resin composition containing 5% by mass of olefin random copolymer elastomer (E-1) was used. All the properties required for the laminated film of the present invention were satisfied.

Example 4
In the heat sealing layer of Example 1, 25% by mass of the ethylene/propylene random copolymer (PP-1) produced by the single-site catalyst method, 5% by mass of the ethylene-propylene random copolymer (PP-2) produced by the single-site catalyst method, and 1- A laminated film was obtained in the same manner as in Example 1, except that a resin composition containing 70% by mass of butene copolymerized linear low-density polyethylene (LL-1) was used. All the properties required for the laminated film of the present invention were satisfied.

Example 5
As the support layer 1, 100% by mass of 1-octene copolymerized linear low-density polyethylene (LL-2) was used, and as the support layer 2, 100% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) was used. A laminated film was obtained in the same manner as in Example 1 except that the ratio was set to %. All the properties required for the laminated film of the present invention were satisfied.

Example 6
A laminated film was obtained in the same manner as in Example 1, except that the same resin composition as in Example 5 was used and the thickness of the heat seal layer was 3 μm. All the properties required for the laminated film of the present invention were satisfied.

Example 7
The same resin composition as in Example 5 was used, and the same as in Example 1 except that the thickness of the support layer was one layer of 35 μm and the thickness of the heat seal layer was 15 μm using a two-layer T-die at 230 ° C. A laminated film was obtained. All the properties required for the laminated film of the present invention were satisfied.

Example 8
Example 5 except that a resin composition containing 70% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) and 30% by mass of high-density polyethylene (HD-1) was used as support layer 1. A laminated film was obtained in the same manner. The properties required for the laminated film of the present invention were satisfied.

Example 9
Except that a resin composition containing 70% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) and 30% by mass of high-density polyethylene (HD-1) was used as support layers 1 and 2. A laminated film was obtained in the same manner as in Example 1. The properties required for the laminated film of the present invention were satisfied.

Example 10
Except that a resin composition containing 90% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) and 10% by mass of plant-derived polyterpene resin (PT-1) was used as support layers 1 and 2. A laminated film was obtained in the same manner as in Example 1. The properties required for the laminated film of the present invention were satisfied.

Example 11
As support layers 1 and 2, a resin composition containing 90% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) and 10% by mass of ethylene-α-olefin random copolymer elastomer (E-1). A laminated film was obtained in the same manner as in Example 1, except that . The properties required for the laminated film of the present invention were satisfied.

Example 12
Except that a resin composition containing 70% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) and 30% by mass of high-pressure low-density polyethylene (LD-1) was used as support layers 1 and 2. A laminated film was obtained in the same manner as in Example 1. The properties required for the laminated film of the present invention were satisfied.

Comparative example 1
Except that a resin composition containing 30% by mass of 1-butene copolymerized linear low-density polyethylene (LL-1) and 70% by mass of high-density polyethylene (HD-1) was used as support layers 1 and 2. A laminated film was obtained in the same manner as in Example 1. The obtained film was evaluated in the same manner as in Example 1. Due to the addition of a large amount of high-density polyethylene to the support layer 1 and the increased crystallinity, both the elongation at break and the strength at break after sealing decreased significantly, and the characteristics required by the present invention were not satisfied.

Comparative example 2
The support layers 1 and 2 had the same composition as Comparative Example 1, and the heat seal layer was made of 70% by mass of a single-site catalyzed ethylene-propylene random copolymer (PP-1) and 1-butene copolymerized linear low-density polyethylene ( A laminated film was obtained in the same manner as in Comparative Example 1, except that a resin composition containing 30% by mass of LL-1) was used. The obtained film was evaluated in the same manner as in Example 1. This film has high breaking elongation and breaking strength before and after sealing, has a large amount of ethylene-propylene random copolymer added to the heat sealing layer, and has a heat sealing strength that is dependent on the number of seconds at a heat sealing temperature of 180°C. Therefore, the characteristics required by the present invention were not satisfied.

Comparative example 3
Support layers 1 and 2 had the same composition as Comparative Example 1, and the heat seal layer was made of 70% by mass of ethylene-propylene random copolymer (PP-2) produced using a single-site catalyst method. A laminated film was obtained. The obtained film was evaluated in the same manner as in Example 1. This film has high breaking elongation and breaking strength before and after sealing, and the high melting point of the ethylene-propylene random copolymer (PP-2) in the heat-sealing layer impairs low-temperature sealability. The heat sealing strength of the second seal was weak, and there was a large difference in the heat sealing strength depending on the number of seconds at a heat sealing temperature of 180° C., and the characteristics required by the present invention were not satisfied.

Comparative example 4
Support layers 1 and 2 had the same composition as in Comparative Example 1, and a laminated film was obtained in the same manner as in Comparative Example 3, except that the heat seal layer had a thickness of 25 μm and the support layer 2 had a thickness of 20 μm. The obtained film was evaluated in the same manner as in Example 1. This film has high breaking elongation and breaking strength before and after sealing, has a thick heat-sealed layer, and has poor peeling appearance.Also, the ethylene-propylene random copolymer (PP-2) has a high melting point. Low-temperature sealability is impaired, heat-sealing strength is weak when sealed at 140°C for 1 second, and there is a large strength difference in second-dependent heat-sealing strength at a heat-sealing temperature of 180°C, which satisfies the characteristics required by the present invention. It wasn't.

Claims (6)

A laminated film having a heat-sealing layer and at least one support layer,
The elongation at break before heat sealing was A1, the strength at break was B1, and the polyethylene terephthalate film was heat sealed at a sealing temperature of 200° C., a sealing pressure of 0.2 MPa, and a sealing time of 1 second, and the polyethylene terephthalate film was peeled off. Regarding the subsequent breaking elongation A2 and breaking strength B2,
A laminated film having A1/A2 of 2.5 or less and B1/B2 of 3.0 or less in both the longitudinal direction and the width direction. The laminated film according to claim 1, wherein the heat sealing degree when the heat sealing layer is heat sealed with a polypropylene sheet at 140° C. for 1 second is 10 N/15 mm or more. The heat seal strength when the heat seal layer is heat sealed with a polypropylene sheet at 180°C for 4 seconds and the peel strength when heat sealed at the same temperature for 1 second are both in the range of 20 N/15 mm or more and 28 N/15 mm or less. The laminated film according to claim 1, wherein the difference therebetween is 3.5 N/15 mm or less. The heat sealing layer is made of a resin composition that is a mixture of polyethylene resin and polypropylene resin, and the polyethylene resin is 51% to 80% by mass and the polypropylene resin is 20% to 49% by mass. 1. The laminated film according to 1. The laminated film according to claim 1, wherein the support layer contains 50% by mass or more of linear low-density polyethylene. 6. The polyethylene resin of the heat-sealing layer contains 50% by mass or more of linear low density polyethylene, and the polypropylene resin contains 20% by mass or more of a single-site catalytic polypropylene resin. Laminated film.