JP2019147853A - Resin composition for intermediate layer and packaging film - Google Patents

Abstract

To provide a resin composition for intermediate layer excellent in heat sealability, heat resistance, and productivity, capable of high speed filling a high temperature ingredient in a wide seal temperature range, and excellent in pressure resistance just after hot filling, and a packaging film using the same.SOLUTION: There is provided a resin composition for intermediate layer containing a copolymer (a1) of at least one kind of ethylene having specific MFR and density, and α-olefin having 3 to 20 carbon atoms, a copolymer (a2) of at least one kind of ethylene having specific MFR and density, and α-olefin having 3 to 20 carbon atoms, and high pressure method low density polyethylene having specific MFR and density, at a specific ratio.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition for an intermediate layer and a packaging film. Specifically, it is excellent in heat sealability, heat resistance and productivity, can be filled at high speed with a high temperature content in a wide range of seal temperatures, and has excellent pressure resistance immediately after hot filling, and uses the same It relates to a packaging film.

In recent years, from the viewpoint of food and beverage hygiene, when filling a packaging bag with food or beverage, filling and packaging of a high-temperature food or beverage that has been subjected to heat sterilization while maintaining the high-temperature state has been widely performed. It is coming.
In addition, in order to meet the demands of consumers who want to eat warm foods and drinks at any time, food and drinks are actively developed assuming high temperature boiling when eating.
And the demand for high heat resistance and high rigidity packaging bags used for such applications is growing rapidly, and for mass production in response to the increased demand for food and drink, it supports high-speed filling packaging. There is also a need to develop packaging bags that can be used.

Conventionally, packaging bags used for filling high temperature liquids that have been heat sterilized, filled liquids and other high temperature boiling, etc. have a base layer and a film made of high melting point polyolefin as a sealant layer. A packaging film having a two-layer structure laminated by dry lamination is known.
From the viewpoint of heat resistance and rigidity, it is generally known that a film made of the same polyolefin has a higher melting point than a low melting point. For example, taking polyethylene as an example, high-density polyethylene (HDPE) is superior in the above properties to low-density polyethylene (LDPE).
However, packaging films made of high-melting polyolefins are inferior in heat-sealability (sealing strength, low-temperature heat-sealability, etc.) because of their high melting points, and therefore require higher-speed automatic filling packaging for liquids and liquids. On the other hand, since the amount of heat supplied to the sealant layer becomes insufficient, it is difficult to ensure proper heat sealing, and high-speed automatic filling and packaging is virtually impossible.

On the other hand, a packaging film using a low-melting-point polyolefin for the sealant layer can obtain heat resistance and rigidity by increasing the thickness of the sealant layer.
However, if the thickness of the sealant layer is increased, it becomes difficult to perform proper heat sealing with a small amount of heat supply, and it becomes impossible to cope with high-speed automatic filling packaging, and because of its low melting point, high temperature contents and boiled There was a problem that the inner surfaces of the bags were fused together by heat.

  As described above, the conventional two-layer packaging film in which a film made of polyolefin having a high melting point as a sealant layer is laminated on the base material layer by dry lamination is compatible with high-speed automatic filling packaging, and has high heat resistance, high rigidity, and There has been a problem that it is impossible to provide a packaging bag having both high heat sealability.

  On the other hand, a packaging film having at least three layers of a base material layer, an intermediate layer, and an innermost layer laminated by extrusion lamination or the like is also widely used in automatic filling packaging, particularly at a high-speed packaging process. However, although it has excellent high heat sealability, there is a problem that heat resistance and rigidity are inferior to packaging films in which films made of high melting point polyolefin are laminated by dry lamination.

Packaging film with excellent heat resistance and heat-sealability that is capable of high-speed automatic filling packaging while maintaining heat resistance and high rigidity comparable to those of conventional two-layer packaging films laminated by dry lamination It is proposed that the density of L-LDPE used for the intermediate layer be 0.920-0.940 g / cm ³ (Japanese Patent Laid-Open No. 2008-302977). However, when such high-density L-LDPE is used as an intermediate layer, there is a problem that the bag breaks if pressure is applied immediately after filling the high-temperature contents.

JP 2008-302977 A

  The present invention has been made with the object of solving the above-mentioned problems of the prior art, and its purpose is the same as that of a conventional two-layer packaging film laminated by dry lamination. The resin composition for the intermediate layer is excellent in heat sealability and productivity while ensuring high heat resistance and rigidity, can be filled at high speed with high temperature contents in a wide range of sealing temperatures, and has excellent pressure resistance immediately after hot filling The object is to provide a product and a packaging film using the product.

  As a result of intensive studies to solve the above problems, the present inventor used an intermediate layer resin composition comprising an ethylene / α-olefin copolymer having a specific composition and physical properties and high-pressure low-density polyethylene, The present inventors have found that the above problems can be solved and have completed the present invention.

That is, the gist of the present invention resides in the inventions of the following items.
[1] A copolymer (a1) of at least one ethylene that satisfies the following requirement [1] and an α-olefin having 3 to 20 carbon atoms, and at least one that satisfies the following requirement [2] A resin composition for an intermediate layer, comprising a copolymer (a2) of ethylene and an α-olefin having 3 to 20 carbon atoms and a high-pressure low-density polyethylene that satisfies the following requirement [3].
Requirement [1] The copolymer (a1) is:
The melt flow rate (MFR) at 2.16 kg load at 190 ° C. is 3 to 20 g / 10 min,
The density is from 0.928 to 0.938 g / cm ³ , and
Requirement [2] The copolymer (a2) is contained in the resin composition in an amount of 40 to 80% by weight.
The melt flow rate (MFR) at 190 ° C. with a load of 2.16 kg is 5 to 30 g / 10 minutes,
The density is from 0.890 to 0.920 g / cm ³ ;
In DSC, only one melting peak is observed, and
Requirement [3] The high-pressure low-density polyethylene is contained in the resin composition in an amount of 10 to 25% by weight.
The melt flow rate (MFR) at 190 ° C. with a load of 2.16 kg is 1 to 20 g / 10 minutes,
The density is 0.915-0.930 g / cm ³ , and
[2] At least one of the copolymer (a1) and the copolymer (a2) is a metallocene catalyst-based ethylene / α-olefin copolymer. The resin composition for intermediate layers according to [1], wherein
[3] The laminate includes at least three layers of a sealant layer (A), an intermediate layer (B), and a base material layer (C), and the intermediate layer (B) is any one of [1] to [2]. A packaging film comprising the intermediate layer resin composition described in 1.
[4] The packaging film as described in [3], which is a film for packaging a content containing a liquid.

  According to the present invention, the resin composition for an intermediate layer, which is excellent in heat sealability, heat resistance and productivity, can be filled at high speed with a high temperature content in a wide sealing temperature range, and has excellent pressure resistance immediately after hot filling, and A packaging film using the same can be provided.

The DSC curve of the resin used is shown. The four curves are the DSC curves of PE-B1, PE-B2, PE-B3, and PE-B4 in order from the top. The DSC curve of the resin used is shown. The three curves are the DSC curves of PE-B5, PE-B6, and PE-B7 in order from the top.

1. Intermediate Layer Resin Composition The intermediate layer resin composition of the present invention comprises a copolymer (a1) of at least one ethylene and an α-olefin having 3 to 20 carbon atoms, at least one ethylene and carbon number. A copolymer (a2) with 3 to 20 α-olefin and high-pressure low-density polyethylene;
Hereinafter, a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms may be referred to as an ethylene / α-olefin copolymer, and the composition containing the ethylene / α-olefin copolymer may be referred to as ethylene / α-olefin copolymer. It may be described as an α-olefin copolymer composition or a copolymer composition.

(1) Ethylene / α-olefin copolymer The resin composition for an intermediate layer of the present invention comprises two types of ethylene / α-olefin copolymers (a1) that can be distinguished by characteristics such as MFR range and density range as described later. ) And (a2), these ethylene / α-olefin copolymers are preferably random copolymers. The α-olefin used as a comonomer of these ethylene / α-olefin copolymers is an α-olefin having 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms, and more preferably 3 to 8 carbon atoms. Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4 , 4-dimethylpentene-1 and the like. Specific examples of the ethylene / α-olefin copolymer include an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, and the like. The above α-olefins are preferred from the viewpoint of resin strength.
One type of α-olefin used as a comonomer may be used, or two or more types may be used simultaneously. For example, a multi-component copolymer using two or more α-olefins such as a terpolymer can also be used. Specific examples include an ethylene / propylene / 1-butene terpolymer, an ethylene / propylene / 1-hexene terpolymer, and when two or more types are used, at least one of them has 6 or more carbon atoms. The α-olefin is preferably from the viewpoint of resin strength.

  The method for producing the ethylene / α-olefin copolymer is not particularly limited as long as an ethylene / α-olefin copolymer composition satisfying the physical properties described below can be obtained, and known methods such as a Ziegler catalyst and a metallocene catalyst are known. It can manufacture using the catalyst of. Among these, it is preferable to use an ethylene / α-olefin copolymer produced by a metallocene catalyst and having physical properties unique to the metallocene catalyst, that is, a so-called metallocene catalyst-based ethylene / α-olefin copolymer.

  The metallocene catalyst is (i) a transition metal compound of Group 4 of the periodic table (hereinafter also referred to as “metallocene compound”) containing a ligand having a cyclopentadienyl skeleton, and (ii) a reaction with a metallocene compound. It is a catalyst comprising a cocatalyst that can be activated to a stable ionic state, and (iii) an organoaluminum compound as an optional component, and a known metallocene catalyst can be appropriately selected and used. Hereinafter, the components (i) to (iii) will be described.

(I) Metallocene Compound The metallocene compound is not particularly limited, and known compounds can be used. For example, JP-A-58-19309, JP-A-59-95292, JP-A-59-23011, JP-A-59-23011 Japanese Patent Laid-Open No. 60-35006, Japanese Patent Laid-Open No. 60-35007, Japanese Patent Laid-Open No. 60-35008, Japanese Patent Laid-Open No. 60-35209, Japanese Patent Laid-Open No. 61-130314, Japanese Patent Laid-Open No. 3-163088, etc. , 436, US Pat. No. 5,055,438, International Publication WO91 / 04257, International Publication WO92 / 07123, and the like.
Specifically, bis (cyclopentadienyl) zirconium dichloride, bis (indenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, bis (azurenyl) zirconium dichloride, bis (4,5,6,7-tetrahydroindenyl) Zirconium dichloride, (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) zirconium dichloride, methylenebis (cyclopentadienyl) zirconium dichloride, methylene (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) ) Zirconium dichloride, isopropylidene (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) zirconium dichloride, ethylene (cyclopentadienyl) (3,5-dimethylpenta) Enyl) zirconium dichloride, methylene bis (indenyl) zirconium dichloride, ethylene bis (2-methylindenyl) zirconium dichloride, ethylene 1,2-bis (4-phenylindenyl) zirconium dichloride, ethylene (cyclopentadienyl) (fluorenyl) Zirconium dichloride, dimethylsilylene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (indenyl) zirconium dichloride, dimethylsilylene bis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, Dimethylsilylene (cyclopentadienyl) (fluorenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (octahydro Olenyl) zirconium dichloride, methylphenylsilylenebis [1- (2-methyl-4,5-benzo (indenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4,5-benzoindenyl)] zirconium Dichloride, dimethylsilylenebis [1- (2-methyl-4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylene Bis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] zirconium dichloride, diphenylsilylene Screw [1- (2- Methyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4- (phenylindenyl))] zirconium dichloride, dimethylsilylenebis [1- (2- Ethyl-4- (phenylindenyl))] zirconium dichloride, dimethylsilylene bis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] zirconium dichloride, dimethylgermylenebis (indenyl) zirconium dichloride, dimethylgermylene Zirconium compounds such as (cyclopentadienyl) (fluorenyl) zirconium dichloride can be exemplified. In the above, a compound in which zirconium is replaced with hafnium can be used similarly. In some cases, a mixture of a zirconium compound and a hafnium compound can be used.
The metallocene compound may be used by being supported on an inorganic or organic compound carrier. The support is preferably a porous oxide of an inorganic or organic compound, specifically, an ion-exchange layered silicate, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO. ZnO, BaO, ThO _{2 and the} like, or a mixture thereof.

(Ii) Cocatalyst Examples of the cocatalyst include organoaluminum oxy compounds (aluminoxane compounds), ion-exchangeable layered silicates, Lewis acids, boron compounds, lanthanoid salts such as lanthanum oxide, tin oxide, and the like.

(Iii) Organoaluminum compound Examples of organoaluminum compounds include trialkylaluminum such as triethylaluminum, triisopropylaluminum, triisobutylaluminum; dialkylaluminum halide; alkylaluminum sesquihalide; alkylaluminum dihalide; alkylaluminum hydride, organoaluminum alkoxide. Side etc. are mentioned.

As the polymerization method, any method can be adopted as long as the catalyst component and each monomer come into efficient contact. Specific examples include a slurry method, a gas phase fluidized bed method and a solution method in the presence of these catalysts, or a high-pressure bulk polymerization method in which a pressure is 200 kg / cm ² or more and a polymerization temperature is 100 ° C. or more. . A preferable production method includes high-pressure bulk polymerization.

  The ethylene / α-olefin copolymer may be appropriately selected from commercially available products. Examples of commercially available products include “Affinity” manufactured by DuPont Dow, “Kernel” and “Harmolex” manufactured by Nippon Polyethylene.

  Next, the ethylene / α-olefin copolymers (a1) and (a2) contained in the copolymer composition will be described in detail.

Ethylene / α-olefin copolymer (a1)
The ethylene / α-olefin copolymer (a1) preferably has a melt flow rate (MFR) at 190 ° C. under a load of 2.16 kg of 3 g / 10 min or more, 20 g / 10 min or less, more preferably 4 g / 10 min. More than 15 g / 10 min. When the MFR is in the above range, the hot tack property, the foaming resistance at the time of high temperature sealing, and the heat resistance are excellent. Here, the MFR of the ethylene / α-olefin copolymer (a1) indicates a melt flow rate at a load of 2.16 kg at 190 ° C., and is also described as MFR (190 ° C., 2.16 kg load).
The ethylene / α-olefin copolymer (a1) preferably has a density of 0.928 g / cm ³ or more and 0.938 g / cm ³ or less, more preferably 0.930 g / cm ³ or more and 0.936 g. / Cm ³ or less. When the density is in the above range, the heat resistance and rigidity are excellent. Here, the density of the ethylene / α-olefin copolymer (a1) indicates a density at 23 ° C. and is also described as a density (23 ° C.).
In addition, MFR (190 degreeC, 2.16 kg load) and a density (23 degreeC) are the values measured based on JIS-K6922-2: 1997 appendix.
In addition, one type of ethylene / α-olefin copolymer (a1) may be used alone, or two or more types may be used.
Further, the content of the ethylene / α-olefin copolymer (a1) in the resin composition for an intermediate layer of the present invention is preferably 40 to 80% by weight. When the content of the ethylene / α-olefin copolymer (a1) is at least the lower limit value, it is preferable from the viewpoint of rigidity and heat resistance, and when it is at most the upper limit value, the pressure resistance and workability are excellent, and the high pressure From the viewpoint of blending with low density polyethylene, it is preferable.

Ethylene / α-olefin copolymer (a2)
The ethylene / α-olefin copolymer (a2) has a melt flow rate (MFR) at a load of 2.16 kg at 190 ° C. of preferably 5 g / 10 min or more, 30 g / 10 min or less, more preferably 7 g / 10 min. As mentioned above, it is 30 g / 10 minutes or less. When the MFR is in the above range, the pressure resistance after hot filling is excellent, the load during extrusion is reduced, and the workability is improved. Here, the MFR of the ethylene / α-olefin copolymer (a2) indicates a melt flow rate at a load of 2.16 kg at 190 ° C., and is also described as MFR (190 ° C., 2.16 kg load).
The ethylene · alpha-olefin copolymer (a2) has a density of preferably 0.890 g / cm ³ or more and 0.920 g / cm ³ or less. When the density is in the above range, heat resistance is not impaired, and the balance with pressure resistance after hot filling is excellent. Here, the density of the ethylene / α-olefin copolymer (a2) indicates a density at 23 ° C. and is also described as a density (23 ° C.).
In addition, MFR (190 degreeC, 2.16 kg load) and a density (23 degreeC) are the values measured based on JIS-K6922-2: 1997 appendix.
The ethylene / α-olefin copolymer (a2) preferably has only one melting peak observed in differential scanning calorimetry (DSC). When the number of melting peaks is only one, a high melting point component is not included, and pressure resistance after hot filling is excellent. The melting peak by DSC of the ethylene / α-olefin copolymer (a2) is measured according to JIS-K7121.
Further, the ethylene / α-olefin copolymer (a2) may be used alone or in combination of two or more.
The content of the ethylene / α-olefin copolymer (a2) in the intermediate layer resin composition of the present invention is preferably 10 to 25% by weight. When the content of the ethylene / α-olefin copolymer (a2) is at least the lower limit value, the pressure resistance is excellent, and when it is at most the upper limit value, it is preferable from the viewpoint of securing rigidity and heat resistance.

  As described above, the ethylene / α-olefin copolymers (a1) and (a2) are preferably metallocene catalyst-based ethylene / α-olefin copolymers. When an ethylene / α-olefin copolymer having different physical properties is used in combination, such as the resin composition for an intermediate layer of the present invention, the method may blend the copolymers with each other or perform multistage polymerization. .

(2) High pressure method low density polyethylene The resin composition for intermediate | middle layers of this invention contains a high pressure method low density polyethylene (HPLD). HPLD can be obtained by a high pressure radical polymerization method, and is also referred to as a high pressure radical polymerization method low density polyethylene. HPLD has a high melt elasticity and is often used to improve neck-in particularly during extrusion lamination.
The physical properties of the high-pressure low-density polyethylene (HPLD) are as follows: Melt flow rate (MFR) at 1.16 kg load at 190 ° C. is 1 to 20 g / 10 min, and density is 0.915 to 0.930 g / cm ³ It is more preferable that the MFR is 1 to 10 g / 10 min and the density is 0.915 to 0.920 g / cm ³ . When the MFR and density are within the above ranges, the balance between neck-in and spreadability during processing is improved. Here, the MFR of the high-pressure low-density polyethylene indicates a melt flow rate at a load of 2.16 kg at 190 ° C., and is also described as MFR (190 ° C., 2.16 kg load). Moreover, the density of the high pressure method low density polyethylene refers to the density at 23 ° C., and is also described as density (23 ° C.).
In addition, MFR (190 degreeC, 2.16 kg load) and a density (23 degreeC) are the values measured based on JIS-K6922-2: 1997 appendix.
Moreover, it is preferable that content of HPLD in the resin composition for intermediate | middle layers of this invention is 10 to 35 weight%. When the HPLD content is less than or equal to the upper limit, low temperature sealing properties and hot tack properties are improved, and when the HPLD content is greater than or equal to the lower limit, neck-in is improved and productivity is improved.

  In addition, the resin composition for an intermediate layer of the present invention is an antioxidant, a heat stabilizer, a weather stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, and an antifogging as long as the effects of the present invention are not significantly impaired. Agents, crystal nucleating agents, neutralizing agents, metal deactivators, colorants, dispersants, slip agents, peroxides, organic or inorganic fillers, optical brighteners, pigments and the like. Moreover, the resin composition for intermediate | middle layers of this invention can contain a small amount of resin components other than an ethylene-alpha-olefin copolymer and a high pressure method low density polyethylene in the range which does not impair the effect of this invention remarkably.

2. Packaging Film The packaging film of the present invention comprises a laminate having at least three layers of a sealant layer (A), an intermediate layer (B), and a base material layer (C), and the intermediate layer (B) is the invention described above. The intermediate layer resin composition is used. In this packaging film, the sealant layer (A) and the intermediate layer (B) are preferably laminated on the base material layer (C) by an extrusion lamination method or a coextrusion lamination method.

  Examples of the base material layer (C) include films such as paper, aluminum foil, cellophane, woven fabric, non-woven fabric, and high-molecular polymer. Examples thereof include high-density polyethylene, medium-density polyethylene, low-density polyethylene, and ethylene / vinyl acetate. Copolymer, ethylene / acrylic acid ester copolymer, ionomer, polypropylene, poly-1-butene, olefin polymer such as poly-4-methylpentene-1, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylate, Vinyl copolymers such as polyacrylonitrile, nylon 6, nylon 66, nylon 7, nylon 10, nylon 11, nylon 12, nylon 610, polyamides such as polymethaxylylene adipamide, polyethylene terephthalate, polyethylene terephthalate / isophthalate, polybutyl Polyesters such as terephthalate, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, may be mentioned a film of polycarbonate. One type of film used as the base material layer (C) may be used, or two or more types may be used. Further, the film may be stretched depending on the type of substrate. Examples of the stretched film include a uniaxial or biaxially stretched polypropylene film, a stretched nylon film, a stretched polyethylene terephthalate film, and a stretched polystyrene film. Furthermore, what coated polyvinylidene chloride, polyvinyl alcohol, etc. on the said film, and what vapor-deposited aluminum, an alumina, a silica, or the mixture of an alumina and a silica may be used as a base material layer (C). In the case of a packaging film containing a liquid or a viscous material, the base material layer (C) is a biaxially stretched nylon film, a biaxially stretched polyethylene terephthalate film, or a material in which silica or alumina is vapor-deposited on the base material. be able to.

  The sealant layer (A) is not particularly limited, and a conventionally known ethylene resin composition can be used. For example, an ethylene / α-olefin copolymer, an ethylene / α-olefin copolymer, and HPLD A blend composition or the like can be used. When performing hot filling, it is desirable to have heat resistance commensurate with the liquid temperature.

  Usually, as a method for producing a laminate, for example, a dry lamination method, a wet lamination method, an extrusion method, a sandwich lamination method, a co-extrusion method and the like can be mentioned. For example, the packaging film used for dry lamination and the like includes any method such as a calendar method, an air-cooled inflation method, a water-cooled inflation method, and a T-die molding method. In the case of an extrusion method, an extrusion lamination method, a dry lamination method, a sandwich lamination method, a coextrusion lamination method (coextrusion without an adhesive layer, coextrusion with an adhesive layer, coextrusion with an adhesive resin, etc. are included. ) Etc.

  In the packaging film of the present invention, when the sealant layer (A) and the intermediate layer (B) are laminated on at least one surface of the base material layer (C), an extrusion lamination method or a coextrusion lamination method is preferably used. . By using these methods, the productivity of the film is excellent. For example, a tandem extrusion laminating method is suitably used as a method for producing a packaging material for contents containing liquid, mucilage, etc. from the viewpoint of productivity and quality. The tandem extrusion laminating method is a method of sequentially laminating two types of resin layers. For example, the intermediate layer (B) is laminated as the first layer on the base material layer (C) by the extrusion laminating method, and further two layers are formed. In this method, the sealant layer (A) is laminated as an eye.

  There is no restriction | limiting in particular about the thickness of the whole laminated body, the thickness of each layer, and the thickness ratio of each layer, and the laminated body which comprises the film for packaging can be suitably selected according to a content, a use, etc. The thickness of the entire laminate is, for example, 40 to 120 μm, the thickness of the base material layer is 10 to 40 μm, and the thickness of the sealant layer is about 10 to 40 μm. The thickness of the intermediate layer can be about 20 to 40 μm. Further, in the case of lamination, surface treatment such as corona discharge treatment, ozone treatment, flame treatment or the like can be performed on the substrate layer in advance in order to improve the adhesion of the substrate surface. Furthermore, in order to enhance the adhesion, etc., the anchor coating agent can be applied on the substrate in advance and then laminated. Examples of the anchor coating agent include isocyanate-based, polyethyleneimine-based, and polybutadiene-based agents.

  The packaging film of the present invention can be used as various packaging materials such as food packaging materials, medical packaging materials, and industrial material packaging materials such as engine oil. Especially, it can use suitably as a film for packaging the content containing a liquid. For example, it can be used as a packaging material for accommodating a liquid containing solid insoluble matter such as liquid, fiber and powder, and a fluid such as a viscous body as contents.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The measurement methods, evaluation methods, and resin materials used in the examples and comparative examples are as follows.

[Measuring method]
(1) Performed according to MFR: JIS K6922-2: 1997 appendix (190 ° C., 21.18 N load).
(2) Density: Performed according to JIS K6922-2: 1997 appendix (23 ° C.).
(3) DSC melting peak: Performed according to JIS-K7121: 2010.

[Filling evaluation method]
(1) Filling liquid The liquid was filled under the following conditions using a liquid automatic filling and packaging machine (manufactured by Taisei Lamic).
[Filling conditions]
Sealing temperature: (vertical) 185 ° C, (horizontal) 110 ° C-190 ° C
Packaging form: Three-sided seal Bag dimensions: 75mm width x 100mm pitch Filling: Water 95 ° C (hot filling)
Filling amount: about 40g
Filling speed: 20 m / min (2) Criteria for filling suitability Filling was performed by changing the transverse seal temperature under the above conditions, and the presence or absence of seal retreat or water leakage was evaluated under the following pressure resistance conditions.
[Pressure resistance condition]
A load was applied at 100 kg for 1 minute with a pressure tester.
[Evaluation criteria]
○: Appearance of the lateral seal was good, there was no receding or water leakage in the pressure resistance evaluation, and no foaming was observed.
Δ: Appearance of the lateral seal is good, but seal receding and water leakage were found in the pressure resistance evaluation.
▲: There was no seal receding or water leakage in the pressure resistance evaluation, but wrinkles were seen on the side seal appearance.
X: No seal retreat or water leakage was observed in the pressure resistance evaluation, but wrinkles and foaming were seen in the lateral seal appearance.
In addition, the pressure test was conducted immediately after filling, and when the bag breakage occurred at any temperature level, the pressure test failed (×), and when no bag breakage occurred, the pressure test passed (○). .
[Extrusion lamination processability]
The intermediate layer resin composition was evaluated by workability when extrusion lamination was performed at 300 ° C. with a thickness of 25 μm.
○: Processed with no particular problems such as extrusion load, neck-in, and spreadability.
×: Some sort of malfunction occurred during processing (excessive extrusion load, excessive neck-in, insufficient stretchability, etc.)

[Resin used]
PE-A1: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 5 g / 10 min, density 0.932 g / cm ³ )
PE-A2: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 5 g / 10 min, density 0.935 g / cm ³ )
PE-A3: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 10 g / 10 min, density 0.935 g / cm ³ )
PE-A4: ethylene / 1-hexene copolymer (linear polyethylene (ZN-LL) produced using a Ziegler catalyst, MFR 2 g / 10 min, density 0.936 g / cm ³ )
PE-B1: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 9 g / 10 min, density 0.918 g / cm ³ , melting peak temperature 107 ° C.)
PE-B2: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 17 g / 10 min, density 0.918 g / cm ³ , melting peak temperature 107 ° C.)
PE-B3: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 17 g / 10 min, density 0.898 g / cm ³ , melting peak temperature 87 ° C.)
PE-B4: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 30 g / 10 min, density 0.911 g / cm ³ , melting peak temperature 95 ° C.)
PE-B5: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 8 g / 10 min, density 0.919 g / cm ³ , melting peak temperature 103, 116, 121 ° C.)
PE-B6: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 12 g / 10 min, density 0.911 g / cm ³ , melting peak temperature 98, 113, 117 ° C.)
PE-B7: ethylene / 1-hexene copolymer (linear polyethylene (mLLD) produced using a metallocene catalyst, MFR 30 g / 10 min, density 0.911 g / cm ³ , melting peak temperature 97, 114 ° C.)
PE-C1: High pressure method low density polyethylene (HPLD) (MFR 4 g / 10 min, density 0.918 g / cm ³ )
PE-C2: High pressure method low density polyethylene (HPLD) (MFR 5 g / 10 min, density 0.918 g / cm ³ )

[Example 1]
[Interlayer resin composition: IL1]
PE-A1: 55 wt% and PE-B2: 18 wt% were used as the ethylene / α-olefin copolymer, and PE-C2: 27 wt% was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender, melt extruded and formed into pellets to obtain an intermediate layer resin composition (IL1).
[Production of evaluation film]
Using an extrusion laminating machine, a biaxially stretched nylon film (Harden film N2102 manufactured by Toyobo Co., Ltd.) having a width of 500 mm and a thickness of 15 μm is used as a base layer, and a two-component anchor coating agent (Seikadine solution manufactured by Dainichi Seika Co., Ltd.) is formed thereon. While coating with a bow roll and ozone spraying at the laminating part, the intermediate layer resin composition IL1 is taken out and melt extruded at a coating thickness of 25 μm and laminated, and the intermediate layer is laminated. did. The extrusion laminator is set so that the temperature of the resin extruded from the T-die mounted on an extruder with a diameter of 90 mmφ is 300 ° C, and is taken up at a cooling roll surface temperature of 25 ° C, a die width of 560 mm, and a die lip opening of 0.7 mm. The extrusion amount was adjusted so that the coating thickness was 25 μm when the processing speed was 100 m / min. Extrusion laminating could be easily processed without any particular problems. Furthermore, on this intermediate layer, the same extrusion laminating apparatus was used, and a sealant layer material (Nippon Polyethylene Kernel KC480, Mitsui Chemicals Tuffmer A4085S 15% by weight, Nippon Polyethylene aliphatic amide-based lubricant was used. A master batch L170SMB (2 parts by weight dry blended) was subjected to melt extrusion laminating at an extrusion resin temperature of 280 ° C., a take-off speed of 100 m / min, and a coating thickness of 25 μm, and a sealant layer was laminated. The laminated film after processing was aged for 48 hours in an oven at 40 ° C., and then slitted to a width of 150 mm to obtain a packaging film for evaluation. The evaluation results of the obtained film are shown in Table 2.

[Examples 2 to 9]
An evaluation film was produced in the same manner as in Example 1 except that the intermediate layer resin composition (IL2-9) obtained by the following method was used for the intermediate layer. In both cases, extrusion laminating could be easily performed without any particular problem. Table 2 shows the evaluation results of the film.
[Interlayer resin composition: IL2]
PE-A2: 60% by weight and PE-B2: 13% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was well blended in a blender and melt extruded to form pellets to obtain an intermediate layer resin composition (IL2).
[Interlayer resin composition: IL3]
PE-A2: 55% by weight and PE-B2: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended with a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL3).
[Interlayer resin composition: IL4]
PE-A2: 50% by weight and PE-B2: 23% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was well blended in a blender and melt extruded to form pellets to obtain an intermediate layer resin composition (IL4).
[Interlayer resin composition: IL5]
PE-A3: 55% by weight and PE-B1: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was well blended in a blender, melt extruded and formed into pellets to obtain an intermediate layer resin composition (IL5).
[Interlayer resin composition: IL6]
PE-A3: 55% by weight and PE-B2: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt extruded to form pellets, thereby obtaining an intermediate layer resin composition (IL6).
[Interlayer resin composition: IL7]
PE-A3: 55% by weight and PE-B3: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt extruded to form pellets, thereby obtaining an intermediate layer resin composition (IL7).
[Interlayer resin composition: IL8]
PE-A3: 55% by weight and PE-B4: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender, melt extruded and formed into pellets to obtain an intermediate layer resin composition (IL8).
[Interlayer resin composition: IL9]
PE-A3: 55% by weight and PE-B1: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt extruded to form pellets, thereby obtaining an intermediate layer resin composition (IL9).

[Comparative Examples 1-8]
An evaluation film was produced in the same manner as in Example 1 except that the intermediate layer resin composition (IL10 to 17) obtained by the following method was used for the intermediate layer. Extrusion laminating could be easily processed without any particular problems. The evaluation results of the film are shown in Table 2.
[Interlayer resin composition: IL10]
PE-A1: 73% by weight was used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender, melt extruded and formed into pellets to obtain an intermediate layer resin composition (IL10).
[Interlayer resin composition: IL11]
PE-A2: 73% by weight was used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL11).
[Interlayer resin composition: IL12]
PE-A3: 73% by weight was used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL12).
[Interlayer resin composition: IL13]
PE-A2: 55% by weight and PE-B7: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was well blended in a blender, melt extruded to form pellets, and an intermediate layer resin composition (IL13) was obtained.
[Interlayer resin composition: IL14]
PE-A2: 55% by weight and PE-B6: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender, melt extruded and formed into pellets to obtain an intermediate layer resin composition (IL14).
[Interlayer resin composition: IL15]
PE-A3: 55% by weight and PE-B6: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C2: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL15).
[Interlayer resin composition: IL16]
PE-A3: 55% by weight and PE-B5: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL16).
[Interlayer resin composition: IL17]
PE-A3: 55% by weight and PE-B7: 18% by weight were used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL17).

[Comparative Example 9]
Except that the intermediate layer resin composition (IL18) obtained by the following method was used for the intermediate layer, an attempt was made to produce an evaluation film in the same manner as in Example 1, but the extrusion load during extrusion lamination was high. Also, the film for evaluation could not be produced because the molten resin film was cut at 100 m / min and the coating thickness was 25 μm (insufficiency in spreadability).
[Interlayer resin composition: IL18]
PE-A4: 73% by weight was used as the ethylene / α-olefin copolymer, and PE-C1: 27% by weight was used as the high-pressure low-density polyethylene. The above resin was thoroughly blended in a blender and melt-extruded into pellets to obtain an intermediate layer resin composition (IL18).

[Reference example]
Example 1 except that a biaxially stretched nylon film having a thickness of 15 μm (Harden film N2102 manufactured by Toyobo Co., Ltd.) and an LLDPE film having a thickness of 50 μm (Rix film L4104 manufactured by Toyobo Co., Ltd.) were obtained by dry lamination to obtain a packaging film. A similar filling evaluation was performed. Table 3 shows the evaluation results of the film.

[Evaluation results]
As shown in Table 2, the films of Examples 1 to 9 have a wide sealing temperature range from a low temperature to a high temperature as compared with the dry laminated product of the reference example. And high-speed liquid filling was possible. In the films of Examples 1 to 9, no bag breakage occurred in the pressure resistance test immediately after hot filling.
On the other hand, the films of Comparative Examples 1 to 8 were capable of high-speed filling at a wider temperature than the dry-laminated product of the reference example as in the examples. It is inferior from a practical viewpoint as a film for use.

Claims (4)

Copolymer (a1) of at least one ethylene satisfying the following requirement [1] and an α-olefin having 3 to 20 carbon atoms, and at least one ethylene and carbon satisfying the following requirement [2] The resin composition for intermediate | middle layers characterized by including the copolymer (a2) with the alpha olefin of several 3-20, and the high-pressure-method low density polyethylene which satisfies the following requirements [3].
Requirement [1] The copolymer (a1) is:
The melt flow rate (MFR) at 2.16 kg load at 190 ° C. is 3 to 20 g / 10 min,
The density is from 0.928 to 0.938 g / cm ³ , and
Requirement [2] The copolymer (a2) is contained in the resin composition in an amount of 40 to 80% by weight.
The melt flow rate (MFR) at 190 ° C. with a load of 2.16 kg is 5 to 30 g / 10 minutes,
The density is from 0.890 to 0.920 g / cm ³ ;
In DSC, only one melting peak is observed, and
Requirement [3] The high-pressure low-density polyethylene is contained in the resin composition in an amount of 10 to 25% by weight.
The melt flow rate (MFR) at 190 ° C. with a load of 2.16 kg is 1 to 20 g / 10 minutes,
The density is 0.915-0.930 g / cm ³ , and
The resin composition contains 10 to 35% by weight.   2. The intermediate layer resin composition according to claim 1, wherein at least one of the copolymer (a1) and the copolymer (a2) is a metallocene catalyst-based ethylene / α-olefin copolymer. .   It consists of a laminated body which has at least 3 layers of a sealant layer (A), an intermediate | middle layer (B), and a base material layer (C), and an intermediate | middle layer (B) is an intermediate | middle layer as described in any one of Claims 1-2. A packaging film comprising a resin composition for packaging.   The packaging film according to claim 3, which is a film for packaging a content containing a liquid.

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