JP2021001032A - Laminated film for packaging and packaging bag - Google Patents

Abstract

To provide a laminated film for packaging excellent in performance balance among heat sealability, peelability and rigidity.SOLUTION: A laminated film 10 for packaging includes at least: a base material layer 20; an ethylenic resin layer (A) containing at least one ethylenic resin selected from first low density polyethylene and an ionomer of an ethylenic-unsaturated carboxylic copolymer; a polyethylene resin layer (B) containing second low density polyethylene (wherein when the ethylenic resin layer (A) contains the first low density polyethylene, the second low density polyethylene has a density higher than that of the first low density polyethylene); and a polyethylene resin layer (C) containing third low density polyethylene having a density lower than that of the second low density polyethylene. The resin layer (A), the resin layer (B) and the resin layer (C) are laminated in this order or the resin layer (B), the resin layer (A) and the resin layer (C) are laminated in this order on the base material layer 20, and the resin layer (C) is the outermost layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laminated film for packaging and a packaging bag.

As a laminated film for packaging, a laminated film in which a sealant layer made of low-density polyethylene or the like is bonded to a base film such as a nylon biaxially stretched film is known.

Examples of the technique related to such a laminated film for packaging include those described in Patent Document 1.
Patent Document 1 describes a laminated film for packaging including at least a base film layer and a heat-sealable sealant layer, wherein the sealant layer is a first sealant layer on the base film layer side and the first sealant. The second sealant layer bonded to the layer is laminated, the first sealant layer is composed of an ionomer resin, and the second sealant layer is a linear low-density polyethylene resin or a low-density polyethylene resin or. Described is a laminated film for packaging, which is characterized by being composed of a polypropylene resin.

Japanese Unexamined Patent Publication No. 2014-133410

The technical standards required for various characteristics of laminated films for packaging are becoming higher and higher. The present inventors have found the following problems with respect to the laminated film for packaging.
First, the laminated film in which the sealant layer containing low-density polyethylene was provided on the base material layer was weak in stiffness and was easily wrinkled or bent. Therefore, such a laminated film is inferior in handleability.
Further, according to the study by the present inventors, in order to strengthen the stiffness of the laminated film, increasing the density or thickness of the low-density polyethylene layer improves the stiffness and improves the handleability, while improving the stiffness. This time, it became clear that the tearability and heat sealability deteriorated.
In other words, it is clear that there is a trade-off relationship between heat sealability and tearability and stiffness, and that trade-off relationship cannot be improved simply by adjusting the density and layer thickness of the low-density polyethylene layer. did. That is, the present inventors have found that there is room for improvement in the conventional laminated film for packaging from the viewpoint of improving heat sealability, tearability and elasticity in a well-balanced manner.

The present invention has been made in view of the above circumstances, and provides a laminated film for packaging having an excellent balance of heat-sealing property, tearing property and elasticity.

The present inventors have made extensive studies to achieve the above problems. As a result, by forming the ethylene resin layer containing a specific ethylene resin and the two types of polyethylene resin layers into a specific layer structure, the above trade-off relationship can be improved, and heat sealability, tearability and tearability can be improved. We have found that the stiffness can be improved in a well-balanced manner, and have reached the present invention.

That is, according to the present invention, the following laminated film for packaging and packaging bag are provided.

[1]
Base layer and
An ethylene resin layer (A) containing at least one ethylene resin selected from the first low-density polyethylene and the ionomer of the ethylene / unsaturated carboxylic acid copolymer,
The polyethylene resin layer (B) containing the second low-density polyethylene (however, when the ethylene-based resin layer (A) contains the first low-density polyethylene, the second low-density polyethylene is the first low-density polyethylene. Higher density than density polyethylene),
A polyethylene resin layer (C) containing a third low-density polyethylene having a lower density than the second low-density polyethylene,
At least
On the base material layer, the resin layer (A), the resin layer (B), and the resin layer (C) are in this order, or the resin layer (B), the resin layer (A), and the resin layer (C). ) Are stacked in this order,
A laminated film for packaging in which the resin layer (C) is the outermost layer.
[2]
In the laminated film for packaging according to the above [1],
A laminated film for packaging in which the density of the second low-density polyethylene is 930 kg / m ³ or more.
[3]
In the laminated film for packaging according to the above [1] or [2],
Packaging laminate film density of the third low-density polyethylene is less than 900 kg / ^{m 3} or more 930 kg / ^{m 3.}
[4]
In the laminated film for packaging according to any one of the above [1] to [3],
A laminated film for packaging having a heat seal strength of 30 N / 15 mm or more at 140 ° C. measured according to JIS K6854-3.
[5]
In the laminated film for packaging according to any one of the above [1] to [4],
A laminated film for packaging having a tear strength of 2.0 N or less in the MD direction measured according to JIS K7128-1.
[6]
In the laminated film for packaging according to any one of the above [1] to [5],
A laminated film for packaging in which the thickness of the ethylene resin layer (A) is 1 μm or more and 50 μm or less.
[7]
In the laminated film for packaging according to any one of the above [1] to [6],
A laminated film for packaging in which the thickness of the polyethylene resin layer (B) is 1 μm or more and 50 μm or less.
[8]
In the laminated film for packaging according to any one of the above [1] to [7],
A laminated film for packaging in which the thickness of the polyethylene resin layer (C) is 1 μm or more and 50 μm or less.
[9]
In the laminated film for packaging according to any one of the above [1] to [8],
A laminated film for packaging in which the average value of loop stiffness values in the MD and TD directions measured under the conditions of 23 ° C., 50% RH, width 25 mm, circumference 100 mm, and pushing distance 15 mm is 100 mN or more and 1000 mN or less.
[10]
In the laminated film for packaging according to any one of the above [1] to [9],
A laminated film for packaging in which the base material layer is a nylon film or a polypropylene film.
[11]
In the laminated film for packaging according to any one of the above [1] to [10],
A laminated film for packaging having an overall thickness of 100 μm or less.
[12]
A packaging bag using the packaging laminated film according to any one of the above [1] to [11].
[13]
The packaging bag according to the above [12], which is a food packaging bag.

According to the present invention, it is possible to provide a laminated film for packaging having an excellent balance of heat sealability, tearability and elasticity.

It is sectional drawing which shows typically an example of the structure of the laminated film for packaging of embodiment which concerns on this invention. It is sectional drawing which shows typically an example of the structure of the laminated film for packaging of embodiment which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Unless otherwise specified, "X to Y" in the numerical range represents X or more and Y or less.

1. 1. Laminated Films for Packaging FIGS. 1 and 2 are cross-sectional views schematically showing an example of the structure of the laminated film 10 for packaging according to the embodiment of the present invention.
The packaging laminated film 10 according to the present embodiment contains ethylene containing a base material layer 20 and at least one ethylene resin selected from the first low-density polyethylene and the ionomer of an ethylene / unsaturated carboxylic acid-based copolymer. A based resin layer (A) (hereinafter, also referred to as a resin layer (A)) and a polyethylene resin layer (B) containing a second low-density polyethylene (hereinafter, also referred to as a resin layer (B)) (however, ethylene. When the based resin layer (A) contains the first low-density polyethylene, the second low-density polyethylene has a higher density than the first low-density polyethylene), and the second low-density polyethylene has a lower density than the second low-density polyethylene. It includes at least a polyethylene resin layer (C) containing the third low-density polyethylene (hereinafter, also referred to as a resin layer (C)).
Then, on the base material layer 20, the resin layer (A), the resin layer (B), and the resin layer (C) are placed in this order, or the resin layer (B), the resin layer (A), and the resin layer (C) are placed in this order. It is laminated, and the resin layer (C) is the outermost layer. When the resin layer (A) contains the first low-density polyethylene, the resin layer (A), the resin layer (B), and the resin layer (C) are laminated in this order, and the resin layer (C) is the outermost layer. It is more preferable to have.

According to the study by the present inventors, the laminated film in which the sealant layer containing low-density polyethylene is provided on the base material layer has a weak stiffness and is easily wrinkled or bent. Therefore, it has become clear that such a laminated film is inferior in handleability.
Further, according to the study by the present inventors, in order to strengthen the stiffness of the laminated film, increasing the density or thickness of the low-density polyethylene layer improves the stiffness and improves the handleability, while improving the stiffness. This time, it became clear that the tearability and heat sealability deteriorated.
That is, it was clarified that there is a trade-off relationship between heat sealability and tearability and stiffness, and that the trade-off relationship cannot be improved only by adjusting the density of the low-density polyethylene layer. That is, the present inventors have found that there is room for improvement in the conventional laminated film for packaging from the viewpoint of improving heat sealability, tearability and elasticity in a well-balanced manner.
The present inventors have made extensive studies to achieve the above problems. As a result, the ethylene resin layer (A), the polyethylene resin layer (B), and the polyethylene resin layer (C) are laminated on the base material layer 20, and the polyethylene resin layer (C) is further arranged on the outermost layer. Therefore, it was found that the above trade-off relationship can be improved, and the heat sealability, tearability and elasticity can be improved in a well-balanced manner.
That is, the packaging laminated film 10 according to the present embodiment has the above-mentioned layer structure, so that the heat-sealability, tearability, and elasticity performance balance can be improved.

In the present embodiment, the overall thickness of the packaging laminated film 10 is preferably 100 μm or less, more preferably 20 μm or more and 90 μm or less, and further preferably 30 μm or more and 80 μm or less. When the overall thickness of the packaging laminated film 10 is at least the above lower limit value, the elasticity and heat-sealing property can be further improved while maintaining the tearability of the packaging laminated film 10. Further, when the total thickness of the packaging laminated film 10 is not more than the above upper limit value, the tearability can be improved while maintaining the elasticity and heat-sealing property of the packaging laminated film 10.

In the packaging laminated film 10 according to the present embodiment, the average value of the loop stiffness values in the MD direction and the TD direction measured under the conditions of 23 ° C., 50% RH, width 25 mm, circumference 100 mm, and pushing distance 15 mm is 100 mN or more. It is preferably 1000 mN or less, and more preferably 120 mN or more and 750 mN or less.
When the average value of the loop stiffness values satisfies the above range, the elasticity of the laminated film 10 for packaging can be further improved while maintaining the heat-sealing property and the tearing property. In order to achieve such an average loop stiffness value, for example, the densities and thicknesses of the resin layer (A), the resin layer (B), and the resin layer (C) may be appropriately adjusted. It is particularly important to adjust the density and thickness of the resin layer (B).

In the packaging laminated film 10 according to the present embodiment, the tear strength in the MD direction measured according to JIS K7128-1 is preferably 2.0 N or less. As a result, the tearability can be further improved while maintaining the heat-sealing property and elasticity of the packaging laminated film 10.
In the packaging laminated film 10, the lower limit of the tear strength in the MD direction is not particularly limited, but is, for example, 0.01 N or more.
In order to achieve such tear strength, the densities and thicknesses of the resin layer (A), the resin layer (B), and the resin layer (C) may be appropriately adjusted, but the resin layer (A) It is especially important to adjust the density and thickness of the plastic.

In the packaging laminated film 10 according to the present embodiment, the heat seal strength at 140 ° C. measured in accordance with JIS K6854-3 is preferably 30 N / 15 mm or more, and more preferably 50 N / 15 mm or more. preferable. As a result, the heat-sealing property can be further improved while maintaining the tearability and elasticity of the packaging laminated film 10.
In the laminated film 10 for packaging, the upper limit of the heat seal strength is not particularly limited, but is, for example, 100 N / 15 mm or less.
In order to achieve such heat seal strength, the densities and thicknesses of the resin layer (A), the resin layer (B), and the resin layer (C) may be appropriately adjusted, but the resin layer (C) ) Is particularly important to adjust the density and thickness.

Hereinafter, each layer constituting the packaging laminated film 10 according to the present embodiment will be described.

<Base layer>
The base material layer 20 is a layer provided for the purpose of improving the handleability, mechanical properties, conductivity, heat insulating property, heat resistance, and other properties of the packaging laminated film 10. Examples of the base material layer 20 include nylon film, polypropylene film, polyester film, polyamide film, polyimide film, polyvinylidene chloride film, ethylene / vinyl acetate copolymer film, aluminum foil, aluminum vapor deposition film, paper and the like. .. These may be used individually by 1 type, or may be used in combination of 2 or more type. These may be uniaxially or biaxially stretched.
Among these, at least one selected from nylon film and polypropylene film is preferable, and at least one selected from biaxially stretched nylon film and biaxially stretched polypropylene film is preferable because it is excellent in mechanical strength, pinhole resistance, and the like. One type is more preferable, and a biaxially stretched nylon film is particularly preferable.

The thickness of the base material layer 20 is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and further preferably 10 μm or more and 30 μm or less from the viewpoint of obtaining good film characteristics.
The base material layer 20 may be surface-treated in order to improve the adhesiveness with other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coating treatment and the like may be performed.

<Ethylene resin layer (A)>
The ethylene resin layer (A) contains at least one ethylene resin selected from the first low density polyethylene and the ionomer of the ethylene / unsaturated carboxylic acid copolymer. By providing the ethylene-based resin layer (A), it is possible to improve the tearability while maintaining the heat-sealing property and elasticity of the packaging laminated film 10.
The thickness of the resin layer (A) is, for example, 1 μm or more and 50 μm or less, preferably 2 μm or more and 30 μm or less, and particularly preferably 5 μm or more and 20 μm or less.

Examples of the first low-density polyethylene according to the present embodiment include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ethylene / α-olefin copolymer, and the like. First but not limited density of the low density polyethylene is particularly, for example, it is preferably less than 900 kg / ^{m 3} or more ^{940kg / m 3, 910kg / m} 3 or more 930 kg / ^m less than ^3, more preferably, 910 kg / ^{m 3} or more 925 kg / Less than m ³ is particularly preferable. Here, the density of the first low-density polyethylene can be measured according to JIS K7112-1999.
When the density of the first low-density polyethylene is at least the above lower limit value, the tearability can be further improved while maintaining the heat-sealing property and elasticity of the packaging laminated film 10.
When the density of the first low-density polyethylene is less than the above upper limit value, the tearability can be further improved while maintaining the transparency of the packaging laminated film 10.

The melt flow rate of the first low-density polyethylene (JIS K7210-1999, 190 ° C., 2160 g load; hereinafter also referred to as MFR) is preferably 0.1 g / 10 minutes or more and 50 g / 10 minutes or less, and is 0. More preferably, it is 5.5 g / 10 minutes or more and 30 g / 10 minutes or less. When the MFR is at least the above lower limit value, the workability of the resin layer (A) can be further improved. When the MFR is not more than the above upper limit value, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The flexural modulus of the first low-density polyethylene is preferably 10 MPa or more and 1000 MPa or less, and more preferably 50 MPa or more and 500 MPa or less. Here, the flexural modulus of the first low-density polyethylene can be measured according to JIS K7171-2008.
When the flexural modulus is within the above range, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The ionomer of the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment is a resin in which the molecules of a polymer obtained by copolymerizing ethylene and at least one of unsaturated carboxylic acids are crosslinked with metal ions. As the ethylene / unsaturated carboxylic acid-based copolymer, a copolymer containing ethylene and an unsaturated carboxylic acid can be exemplified.

Examples of the unsaturated carboxylic acid constituting the ionomer of the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment include acrylic acid, methacrylic acid, 2-ethylacrylic acid, crotonic acid, maleic acid, fumaric acid, and the like. Examples thereof include itaconic acid, maleic anhydride, fumaric anhydride, itaconic anhydride, monomethyl maleate, and monoethyl maleate.
Among these, the unsaturated carboxylic acid preferably contains at least one selected from acrylic acid and methacrylic acid from the viewpoint of productivity, hygiene and the like of the ethylene / unsaturated carboxylic acid-based copolymer. These unsaturated carboxylic acids may be used alone or in combination of two or more.
In the present embodiment, a particularly preferable ethylene / unsaturated carboxylic acid-based copolymer is an ethylene / (meth) acrylic acid copolymer.

In the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment, the structural unit derived from ethylene is preferably 65% by mass or more and 95% by mass or less, and more preferably 75% by mass or more and 92% by mass or less.
When the structural unit derived from ethylene is at least the above lower limit value, the heat resistance, mechanical strength, etc. of the obtained film can be improved. Further, when the structural unit derived from ethylene is not more than the above upper limit value, the transparency, flexibility, adhesiveness and the like of the obtained laminated film 10 for packaging can be improved.

In the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment, the structural unit derived from the unsaturated carboxylic acid is preferably 5% by mass or more and 25% by mass or less, more preferably 8% by mass or more and 25% by mass or less. Is.
When the structural unit derived from the unsaturated carboxylic acid is at least the above lower limit value, the transparency, flexibility, adhesiveness, etc. of the obtained film can be improved. Further, when the structural unit derived from the unsaturated carboxylic acid is not more than the above upper limit value, the processability of the resin layer (A) can be improved.

The ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment is preferably derived from other copolymerizable monomers of 0% by mass or more and 30% by mass or less, more preferably 0% by mass or more and 25% by mass or less. Constituent units may be included. Other copolymerizable monomers include unsaturated esters such as vinyl acetate, vinyl esters such as vinyl propionate; methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic. Examples thereof include (meth) acrylic acid esters such as n-butyl acid and 2-ethylhexyl (meth) acrylic acid. It is preferable that the structural unit derived from the other copolymer monomer is contained within the above range because the flexibility of the obtained film is improved.

Examples of the metal ion constituting the ionomer of the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment include alkali metal ions such as lithium ion, potassium ion, and sodium ion; calcium ion, magnesium ion, zinc ion, and aluminum ion. , Polyvalent metal ions such as barium ion and the like.
Among these, it is preferable to contain at least one selected from sodium ion and zinc ion. These metal ions may be used alone or in combination of two or more.

The degree of neutralization of the ionomer of the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment is not particularly limited, but is preferably 85% or less, more preferably 80% or less, from the viewpoint of further improving processability and moldability. preferable.
The degree of neutralization of the ionomer of the ethylene / unsaturated carboxylic acid-based copolymer according to the present embodiment is not particularly limited, but from the viewpoint of further improving the processability and the heat resistance of the obtained laminated film 10 for packaging. 5% or more is preferable, 10% or more is more preferable, and 15% or more is particularly preferable.

The method for producing the ethylene / unsaturated carboxylic acid-based copolymer is not particularly limited, and the copolymer can be produced by a known method. For example, it can be obtained by radical copolymerizing each polymerization component under high temperature and high pressure. Further, the ionomer of the ethylene / unsaturated carboxylic acid-based copolymer can be obtained by reacting the ethylene / unsaturated carboxylic acid-based copolymer with a metal compound. Further, as the ionomer of the ethylene / unsaturated carboxylic acid-based copolymer, a commercially available one may be used.

In the present embodiment, the melt flow rate (MFR) of the ethylene / unsaturated carboxylic acid-based copolymer ionomer measured under the conditions of 190 ° C. and 2160 g load according to JIS K7210: 1999 is 0.01 g / g. It is preferably 10 minutes or more and 50 g / 10 minutes or less, more preferably 0.1 g / 10 minutes or more and 30 g / 10 minutes or less, and particularly preferably 0.1 g / 10 minutes or more and 10 g / 10 minutes or less. preferable. When the MFR is at least the above lower limit value, the workability of the resin layer (A) can be further improved. When the MFR is not more than the above upper limit value, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The resin layer (A) can contain components other than the first low-density polyethylene and the ethylene / unsaturated carboxylic acid-based copolymer ionomer as long as the object of the present invention is not impaired. Other components are not particularly limited, but are, for example, plasticizers, antioxidants, ultraviolet absorbers, antistatic agents, surfactants, colorants, light stabilizers, foaming agents, lubricants, crystal nucleating agents, and crystallization. Accelerators, crystallization retardants, catalyst deactivators, thermoplastic resins, thermosetting resins, inorganic fillers, organic fillers, impact resistance improvers, slip agents, cross-linking agents, cross-linking aids, tackifiers, Silane coupling agent, processing aid, mold release agent, hydrolysis inhibitor, heat stabilizer, anti-blocking agent, antifogging agent, flame retardant, flame retardant aid, light diffusing agent, antibacterial agent, anticorrosive agent, dispersion Examples include agents and other resins. Other components may be used alone or in combination of two or more.

<Polyethylene resin layer (B)>
The polyethylene resin layer (B) contains the second low density polyethylene (however, when the ethylene resin layer (A) contains the first low density polyethylene, the second low density polyethylene is more than the first low density polyethylene. Is also dense). By providing the polyethylene resin layer (B), it is possible to improve the elasticity while maintaining the heat sealability and tearability of the packaging laminated film 10.
The thickness of the resin layer (B) is, for example, 1 μm or more and 50 μm or less, preferably 2 μm or more and 40 μm or less, and particularly preferably 5 μm or more and 30 μm or less.

Examples of the second low-density polyethylene according to the present embodiment include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ethylene / α-olefin copolymer, and the like. While the second non density of the low density polyethylene is particularly limited, for example, preferably from 930 kg / ^{m 3} or higher, more preferably less than 930 kg / ^{m 3} or more ^{945kg / m 3, 935kg / m} 3 or more 942kg / ^m less than ³ and more It is preferably 938 kg / m ³ or more and less than 942 kg / m ³ . Here, the density of the second low-density polyethylene can be measured according to JIS K7112-1999.
When the density of the second low-density polyethylene is at least the above lower limit value, the stiffness can be further improved while maintaining the heat-sealing property and the tearing property of the packaging laminated film 10.
When the density of the second low-density polyethylene is less than the above upper limit value, the tearability can be further improved while maintaining the transparency of the packaging laminated film 10.

The melt flow rate (JIS K7210-1999, 190 ° C., 2160 g load) of the second low-density polyethylene is preferably 0.1 g / 10 minutes or more and 50 g / 10 minutes or less, and 0.5 g / 10 minutes or more and 30 g. More preferably, it is 10 minutes or less. When the MFR is at least the above lower limit value, the workability of the resin layer (B) can be further improved. When the MFR is not more than the above upper limit value, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The flexural modulus of the second low-density polyethylene is preferably 10 MPa or more and 1000 MPa or less, and more preferably 50 MPa or more and 500 MPa or less. Here, the flexural modulus of the second low-density polyethylene can be measured according to JIS K7171-2008.
When the flexural modulus is within the above range, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The resin layer (B) can contain components other than the second low-density polyethylene as long as the object of the present invention is not impaired. The other components are not particularly limited, but for example, the same components as those exemplified in the resin layer (A) can be used.

<Polyethylene resin layer (C)>
The polyethylene resin layer (C) is composed of a third low-density polyethylene having a lower density than the second low-density polyethylene. By providing the polyethylene resin layer (C), it is possible to improve the heat sealability while maintaining the elasticity and tearability of the packaging laminated film 10.
The thickness of the resin layer (C) is, for example, 1 μm or more and 50 μm or less, preferably 2 μm or more and 40 μm or less, and particularly preferably 5 μm or more and 30 μm or less.

Examples of the third low-density polyethylene according to the present embodiment include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ethylene / α-olefin copolymer, and the like. The third is the density of the low density polyethylene is not particularly limited, for example, is preferably less than 900 kg / ^{m 3} or more ^{930kg / m 3, 900kg / m} 3 or more 920 kg / ^m less than ^3, more preferably, 910 kg / ^{m 3} or more 920 kg / Less than m ³ is particularly preferable. Here, the density of the third low-density polyethylene can be measured according to JIS K7112-1999.
When the density of the third low-density polyethylene is at least the above lower limit value, the elasticity of the laminated film 10 for packaging can be further improved while maintaining the heat-sealing property and the tearing property.
When the density of the third low-density polyethylene is less than the above upper limit value, the heat-sealing property can be further improved while maintaining the transparency of the packaging laminated film 10.

The melt flow rate (JIS K7210-1999, 190 ° C., 2160 g load) of the third low-density polyethylene is preferably 0.1 g / 10 minutes or more and 50 g / 10 minutes or less, and 0.5 g / 10 minutes or more and 30 g. More preferably, it is 10 minutes or less. When the MFR is at least the above lower limit value, the workability of the resin layer (C) can be further improved. When the MFR is not more than the above upper limit value, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The flexural modulus of the third low-density polyethylene is preferably 10 MPa or more and 1000 MPa or less, and more preferably 50 MPa or more and 500 MPa or less. Here, the flexural modulus of the third low-density polyethylene can be measured according to JIS K7171-2008.
When the flexural modulus is within the above range, the elasticity of the packaging laminated film 10 can be further improved while maintaining the tearability of the packaging laminated film 10.

The resin layer (C) can contain components other than the third low-density polyethylene as long as the object of the present invention is not impaired. The other components are not particularly limited, but for example, the same components as those exemplified in the resin layer (A) can be used.

<Other layers>
The packaging laminated film 10 according to the present embodiment may be composed of only four layers of a base material layer 20, a resin layer (A), a resin layer (B), and a resin layer (C), or may be used for packaging. From the viewpoint of imparting various functions to the laminated film 10, it may have layers other than the above four layers (hereinafter, also referred to as other layers). Examples of other layers include an inorganic layer, a gas barrier layer, an antistatic layer, a hard coat layer, an adhesive layer, an antireflection layer, an antifouling layer, an undercoat layer and the like. The other layers may be used alone or in combination of two or more layers.

<Use>
The packaging laminated film 10 according to the present embodiment can be used for packaging, for example, foods, pharmaceuticals, industrial products, daily necessities, etc., and can be particularly preferably used as a food packaging film.

2. 2. Packaging bag The packaging bag according to the present embodiment includes the packaging laminated film 10 according to the present embodiment. The form is not particularly limited, and examples thereof include a three-sided bag, a four-sided bag, a pillow bag, a gusset bag, and a stick bag. The packaging bag according to the present embodiment can be used as, for example, a food packaging bag, a pharmaceutical packaging bag, an industrial product packaging bag, a daily product packaging bag, or the like. In particular, it can be suitably used as a food packaging bag.

3. 3. Method for Producing Laminated Film for Packaging The method for producing the laminated film 10 for packaging according to the present embodiment is not particularly limited, and a molding method generally used for thermoplastic resins can be applied. For example, it can be carried out by a known method using a T-die extruder, an inflation molding machine or the like.
A method of extrusion laminating the resin layer (A), the resin layer (B), and the resin layer (C) on the base material layer 20 can be used.

Although the embodiments of the present invention have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than the above can be adopted.

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

The details of the materials used for producing the laminated film for packaging are as follows.

<Low density polyethylene>
LDPE1: Linear low density polyethylene (LLDPE, density: 940 kg / m ³ , MFR: 14 g / 10 minutes, flexural modulus: 325 MPa, manufactured by Prime Polymer Co., Ltd.)
LDPE2: Linear low density polyethylene (LLDPE, density: 914 kg / m ³ , MFR: 11 g / 10 minutes, flexural modulus: 130 MPa, manufactured by Prime Polymer Co., Ltd.)
LDPE3: Linear low density polyethylene (LLDPE, density: 910 kg / m ³ , MFR: 10 g / 10 minutes, flexural modulus: 150 MPa, manufactured by Prime Polymer Co., Ltd.)
LDPE4: Low density polyethylene (LDPE, density: 923 kg / m ³ , MFR: 3.7 g / 10 minutes, flexural modulus: 220 MPa, manufactured by Mitsui Chemicals, Inc.)

<Ionomer of ethylene / unsaturated carboxylic acid copolymer>
IO-1: Ionomer of ethylene / methacrylic acid copolymer (ethylene content 85% by mass, methacrylic acid content: 15% by mass, 30% Na neutralization, MFR: 3 g / 10 minutes)

<Base layer>
ONy (biaxially stretched nylon film, manufactured by Unica, thickness: 15 μm)

[Examples 1 to 7, Comparative Examples 1 to 6]
Each layer was extruded and laminated on the base material layer with the layer structure shown in Table 1 to obtain a laminated film. The extrusion laminating conditions are as follows.
Extruder: 65mmφ extruder (L / D = 28, manufactured by Sumitomo Heavy Industries Modern Co., Ltd.)
Extrusion set temperature: 300 ° C, processing speed: 80 m / min
The surface of the base material layer was subjected to ozone treatment and anchor coating treatment with an anchor coating agent.
The following evaluations were performed on the obtained laminated film. The results obtained are shown in Table 1.

<Evaluation>
(1) Adhesiveness of base material layer The base material layer was peeled off under the following conditions, and the peeled state of the base material layer was observed.
23 ° C, 50% RH, T-type peeling (90 degree peeling), peeling speed 300 mm / min

(2) Heat seal strength The heat seal strength at 140 ° C. was measured according to JIS K6854-3.
-Heat seal conditions: temperature 140 ° C, pressure 0.3 MPa (gauge), time 0.5 seconds, seal width 10 mm
-Heat seal strength measurement conditions: 23 ° C, 50% RH, T-type peeling (90 degree peeling), peeling speed 300 mm / min

(3) Loop Stiffness Value Using a loop stiffness tester manufactured by Toyo Seiki Co., Ltd., the loop stiffness values in the MD direction and the TD direction were measured under the conditions of 23 ° C., 50% RH, width 25 mm, circumference 100 mm, and pushing distance 15 mm.
As the measurement sample, a double-layer film was prepared by heat-laminating the polyethylene resin layer (C) as an inner surface.

(4) Tear strength The tear strength in the MD direction was measured according to JIS K7128-1.

The laminated films of Examples 1 to 7 had high heat seal strength and low tear strength. In addition, the average value of the loop stiffness values was an appropriate value, and the handling was excellent. That is, the laminated films of Examples 1 to 7 were excellent in heat sealability, tearability, and elasticity performance balance. On the other hand, the laminated films of Comparative Examples 1 to 6 were inferior in heat-sealing property, tearing property, and elasticity performance balance.

A Ethylene resin layer B Polyethylene resin layer C Polyethylene resin layer 10 Laminated film for packaging 20 Base material layer

Claims (13)

Base layer and
An ethylene resin layer (A) containing at least one ethylene resin selected from the first low-density polyethylene and the ionomer of the ethylene / unsaturated carboxylic acid copolymer,
The polyethylene resin layer (B) containing the second low-density polyethylene (however, when the ethylene-based resin layer (A) contains the first low-density polyethylene, the second low-density polyethylene is the first low-density polyethylene. Higher density than density polyethylene),
A polyethylene resin layer (C) containing a third low-density polyethylene having a lower density than the second low-density polyethylene,
At least
On the base material layer, the resin layer (A), the resin layer (B), and the resin layer (C) are in this order, or the resin layer (B), the resin layer (A), and the resin layer (C). ) Are stacked in this order,
A laminated film for packaging in which the resin layer (C) is the outermost layer. In the laminated film for packaging according to claim 1,
A laminated film for packaging in which the density of the second low-density polyethylene is 930 kg / m ³ or more. In the laminated film for packaging according to claim 1 or 2.
It said third laminated film for packaging density of the low density polyethylene is less than 900 kg / ^{m 3} or more 930 kg / ^{m 3.} In the laminated film for packaging according to any one of claims 1 to 3.
A laminated film for packaging having a heat seal strength of 30 N / 15 mm or more at 140 ° C. measured according to JIS K6854-3. In the laminated film for packaging according to any one of claims 1 to 4.
A laminated film for packaging having a tear strength of 2.0 N or less in the MD direction measured according to JIS K7128-1. In the laminated film for packaging according to any one of claims 1 to 5,
A laminated film for packaging in which the thickness of the ethylene resin layer (A) is 1 μm or more and 50 μm or less. In the laminated film for packaging according to any one of claims 1 to 6.
A laminated film for packaging in which the thickness of the polyethylene resin layer (B) is 1 μm or more and 50 μm or less. In the laminated film for packaging according to any one of claims 1 to 7.
A laminated film for packaging in which the thickness of the polyethylene resin layer (C) is 1 μm or more and 50 μm or less. In the laminated film for packaging according to any one of claims 1 to 8.
A laminated film for packaging in which the average value of the loop stiffness values in the MD and TD directions measured under the conditions of 23 ° C., 50% RH, width 25 mm, circumference 100 mm, and pushing distance 15 mm is 100 mN or more and 1000 mN or less. In the laminated film for packaging according to any one of claims 1 to 9.
A laminated film for packaging in which the base material layer is a nylon film or a polypropylene film. In the laminated film for packaging according to any one of claims 1 to 10.
A laminated film for packaging having an overall thickness of 100 μm or less. A packaging bag using the packaging laminated film according to any one of claims 1 to 11. The packaging bag according to claim 12, which is a packaging bag for food.

Images