JP2022039843A - Polyethylene resin composition for stretched base material film and stretched base material film made of the same - Google Patents

Abstract

To provide a polyethylene resin composition for a stretched base material which is excellent in stretchability and rigidity, and is suitable as a stretched base material, and a resin laminate and a packaging material using the same.SOLUTION: A polyethylene resin composition for a stretched base material film that is used as a base material of a resin laminate satisfies the following physical properties (a-1) to (a-4): (a-1) a density of 0.935-0.970 g/cm3; (a-2) a melt flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg of 0.1-7 g/10 min; (a-3) a value of a melt tension (MT) at 190°C of 8.0 g or less; and (a-4) molecular weight distribution by gel permeation chromatography (GPC) [ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)] of 1.5 to 10.0.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polyethylene resin composition for a stretched base film, a stretched base film obtained by stretching a film made of the polyethylene resin composition, a laminate containing the stretched base film, and a packaging material composed of the laminate. ..

Conventionally, one of the basic configurations of a packaging material is to bond a heat seal layer and a base material layer with an adhesive. Of these, a film made of a polyethylene resin composition having appropriate flexibility, transparency, and heat-sealing properties is widely used as the heat-sealing layer. On the other hand, as the base material layer, a film obtained by stretching a film made of a polyester resin composition or a polyamide resin composition is used from the viewpoint of rigidity, impact resistance, and heat resistance (see Patent Document 1).

In recent years, with the growing demand for the construction of a sound material-cycle society, packaging materials with high recyclability are required. However, the conventional packaging material is composed of different kinds of resin materials as described above, and it is difficult to separate each resin material, so that the conventional packaging material is not recycled at present.

As a method of providing high recyclability, there is an example of forming a packaging material (monomaterial packaging material) made of the same resin material. Since polyethylene resin compositions are widely used as raw materials for packaging materials, monomaterial packaging materials composed of a film consisting of a polyethylene resin composition for both the heat seal layer and the base material layer are recyclable to realize a recycling-oriented society. It is expected as a high-quality packaging material.

However, when a film made of a polyethylene resin composition is used as a base material layer, if the film obtained by the inflation molding method or the T-die molding method is used as it is, not only the strength of the packaging material is insufficient, but also the film when printed. Is stretched and the image is out of alignment. To compensate for this, a film obtained by stretching a film obtained by molding a polyethylene resin composition by an inflation molding method or a T-die molding method is used.
As a polyethylene resin composition for a stretched film, for example, a resin composition in which LLDPE and HDPE are blended (see Patent Document 2) and LLDPE having a specific crystal component (see Patent Document 3) have been proposed, but both are base materials. However, since it is a polyethylene resin composition intended for shrink film applications, it has been desired to develop a polyethylene resin composition intended for a stretched base material.

Japanese Unexamined Patent Publication No. 2009-20251 Japanese Unexamined Patent Publication No. 2005-89693 Japanese Unexamined Patent Publication No. 2004-238543

An object of the present invention is to provide a polyethylene resin composition for a stretched base material, which is excellent in stretchability and rigidity and is suitable as a stretched base material, and a resin laminate and a packaging material using the same.

As a result of diligent research to solve the above problems, the present inventors formed a film of a polyethylene resin composition satisfying a specific condition by inflation molding, and stretched the obtained film with a thermal roll stretching machine. As a result, they have found that they exhibit characteristics that can solve the above problems, and have completed the invention based on these findings.

That is, according to the present invention [1], there is provided a polyethylene resin composition for a stretched base film, which is characterized by satisfying the following physical properties (a-1) to (a-4).
(A-1) The density is 0.935 to 0.970 g / cm ³ (a-2) The melt flow rate (MFR) at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 7.0 g / 10 min. (A-3) The value of melt tension (MT) at 190 ° C. is 8.0 g or less. (A-4) Molecular weight distribution by gel permeation chromatography (GPC) [Weight average molecular weight (Mw) and number average molecular weight. (Mw / Mn)] is 1.5 to 10.0.

Further, according to the present invention [2], a film obtained by stretching a film obtained by inflating or T-die molding the polyethylene resin composition according to the first invention is stretched 7 times over MD. It exists in the region satisfying the equations (1), (2) and (3) when the tensile elastic modulus in the mechanical direction (MD) of the film is EM and the tensile elastic modulus in the orthogonal direction (TD) is ET. Provided is a polyethylene resin composition characterized by the above.
(1) ET ≧ 1500
(2) EM ≧ ET-400
(3) EM ≤ 3ET

Further, according to the present invention [3], a stretching group obtained by stretching a film obtained by inflation molding or T-die molding using the polyethylene resin composition described in the first or second invention. Material film is provided.

Further, according to the present invention [4], the film obtained by inflation molding or T-die molding is stretched 7 times or more on MD by using the polyethylene resin composition described in the first or second invention. The stretched base film thus obtained is provided.

Further, according to the present invention [5], the film obtained by inflation molding or T-die molding using the polyethylene resin composition described in the first or second invention is more than twice as much as MD and TD. A stretched base film obtained by stretching is provided.

Further, according to the present invention [6], there is provided a resin laminate containing a layer made of the stretched base film according to any one of the third to fifth inventions.

Further, according to the present invention [7], a resin laminate containing a layer made of the stretched base film according to any one of the third to fifth inventions as a base material and a polyethylene-based resin sealant layer as a sealant layer is provided. Will be done.

Further, according to the present invention [8], a monomaterial resin laminate in which the resin laminate according to the sixth or seventh invention is entirely made of a polyethylene-based resin is provided.

Further, according to the present invention [9], a packaging material using the resin laminate according to the sixth to eighth inventions is provided.

The polyethylene resin composition of the present invention can provide a stretched base film having excellent stretchability and rigidity. Since it is possible to print on the surface of such a stretched base film, by using the stretched base film as a base material for a packaging material and using it in combination with a polyethylene sealant film, packaging with high recyclability is possible. It is possible to provide a monomaterial laminate and a packaging material composed of a material, particularly a single material.

It is a figure which shows the relationship between EM and ET of the stretched base film produced using the polyethylene resin composition of this invention.

The present invention relates to a polyethylene resin composition for a stretched base film and a stretched base film comprising the polyethylene resin composition.
Hereinafter, the present invention will be described in detail for each item. The stretched base film of the present invention is a film obtained by stretching a film obtained by inflation molding or T-die molding of a polyethylene resin composition satisfying the requirements of the present invention, and is a resin laminate. It means a stretched film used as a base material of.

1. 1. Polyethylene resin composition The polyethylene resin composition in the present invention is a resin composition used as a raw material for a stretched base film, and means both a polyethylene resin alone or a polyethylene resin mixture thereof, to which necessary additives are added. May be.
-Polyethylene resin composition polymerization catalyst and polymerization method The polyethylene resin for constituting the polyethylene resin composition is made from either ethylene derived from a petroleum raw material, ethylene derived from a biomass raw material, or both. It is manufactured by using a conventionally known catalyst such as a polymerization catalyst such as a Ziegler-Natta catalyst, a phillips catalyst, or a metallocene catalyst. A Ziegler-Natta catalyst or a metallocene catalyst is preferable. Generally, these catalysts are in a state where a complex composed of an organometallic compound is supported on a carrier such as silica or Mg compound.
The polymerization method may be any of a solution method, a slurry method and a gas phase method, but a slurry method and a gas phase method are preferable. Here, the slurry method is a polymerization method in which a hydrocarbon compound such as hexane or isobutane is used as a solvent and the produced polyethylene is present in the solvent as a slurry. Depending on the shape of the reaction vessel, it is roughly divided into two methods, the autoclave method and the loop pipe method. The vapor phase method is a polymerization method in which ethylene and α-olefin as a comonomer and hydrogen as a chain transfer agent are fed in a gas state from the lower part of a vertical reaction vessel, and a polymerization catalyst is charged therein. (Edited by Kazuo Matsuura, Naotaka Mikami / Polyethylene Technology Reader)

-Polymerization method of polyethylene resin composition using slurry method In addition, both the autoclave method and the loop pipe method of the slurry method are capable of single-stage polymerization and multi-stage polymerization. Multistage polymerization is a method of sequentially and continuously polymerizing with a plurality of polymerization reactors connected in series or in parallel, for example, two polymerization reactors. The polymerization can be carried out in an organic solvent or in a liquid monomer.
In this multi-stage polymerization, for example, in the first stage, ethylene or α-olefin is copolymerized to produce polyethylene as a high molecular weight component, and then ethylene and hydrogen are introduced into the polymerization system to produce a second step. At the stage, polyethylene as a low molecular weight component can be produced, and as a result, polyethylene containing a high molecular weight component and a low molecular weight component can be prepared. Further, polyethylene as a low molecular weight component may be produced in the first stage, and polyethylene as a high molecular weight component may be produced in the second stage.
In the case of multi-stage polymerization, the amount of polyethylene produced in the polymerization region from the second stage onward and its properties are determined by determining the amount of polyethylene produced after each polymerization reactor (which can be grasped by unreacted gas analysis, etc.). The physical properties of polyethylene can be obtained by measuring the physical properties of the polymer extracted after each polymerization reactor and converting from the additive nature of the physical properties.
The polyethylene resin compositions obtained by these methods have a wide range of combinations of various densities, melt flow rates (MFRs), melt tensions (MTs), and molecular weight distributions in order to meet various conventionally known applications. Among them, the polyethylene resin composition for a stretched base film of the present invention is characterized in that a polyethylene resin having a specific density, melt flow rate (MFR), melt tension (MT), and molecular weight distribution is selected and used. And.

-Commonomer composition of polyethylene resin composition The polyethylene resin composition according to the present invention is an ethylene homopolymer or a copolymer of ethylene and one or more α-olefins selected from α-olefins having 3 to 18 carbon atoms. Is. The α-olefin having 3 to 18 carbon atoms is preferably one having 3 to 12 carbon atoms, and specifically, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-. Examples include penten. Further, it is desirable that the content of these α-olefins be selected in the range of usually 30 mol% or less, preferably 20 mol% or less in total. Within this range, the flexibility and heat resistance of the film or the like will be good.
Here, the content of α-olefin is a value measured by the 13C-NMR method under the following conditions.
Equipment: JEOL-GSX270 manufactured by JEOL
Concentration: 300 mg / 2 mL
Solvent: Orthodichlorobenzene

-Density The polyethylene resin composition for a stretched film of the present invention is required to have a density in the range of 0.935 to 0.970 g / cm ³ . The preferred density is in the range of 0.940 to 0.965 g / cm ³ , more preferably 0.945 to 0.965 g / cm ³ . Here, the density is a value measured according to JIS K6922-1 and 2.
If the density is less than 0.935 g / cm ³ , the rigidity of the stretched film for a base material becomes small, which is not preferable. On the other hand, if the density exceeds 0.970 g / cm ³ , the formability of the film itself deteriorates, which is not preferable.

・ Melt flow rate (MFR)
The polyethylene resin composition requires that the MFR be in the range of 0.1 to 7 g / 10 min. The preferred MFR is in the range of 0.1 to 6 g / 10 min, more preferably 0.1 to 5 g / 10 min. If the MFR is less than 0.1 g / 10 min, gel or the like may be generated, while if the MFR exceeds 7 g / 10 min, a stretched film for a substrate having high mechanical strength cannot be obtained, which is not preferable. That is, when the MFR is in the range of 0.1 to 7 g / 10 min, a stretched film for a base material can be obtained without generation of gel or the like, which is preferable. The MFR was measured by extruding the molten polymer from a die (length 8 mm, outer diameter 9.5 mm, inner diameter 2.095 mm) at 190 ° C. and a load of 2.16 kg in accordance with JIS K6922-2. Extrusion speed.

・ Melt tension (MT)
The polyethylene resin composition is required to have an MT of 8.0 g or less. If the MT is larger than this, the stretched film will break at a low stretching ratio during the production of the stretched film, which is not preferable. The MT extrudes a resin heated and stabilized at 190 ° C. in a furnace from an orifice having an inner diameter of 2.095 mm and a length of 8 mm at a piston speed of 1 cm / min, and pulls the extruded molten resin at a speed of 4 m / min. It is the resistance generated at that time.

-Molecular weight distribution For polyethylene resin compositions, it is essential that the molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)] is in the range of 1.5 to 10.0. do. The preferred range of Mw / Mn ratio is 2.0 to 9.0. If Mw / Mn exceeds 10.0, the obtained stretched film for a substrate may have low rigidity and may become an opaque film, which is not preferable. It is preferable to use the polyethylene resin composition having Mw / Mn in the range of 1.5 to 10.0 because it is possible to obtain the optimum raw fabric film for the stretched base film.

-Resin Blend In the present invention, the polyethylene resin composition may be a single one, but two or more kinds may be mixed to produce a polyethylene resin that simultaneously satisfies the above requirements, and the polyethylene resin may be used.

-Additives The polyethylene resin or resin composition according to the present invention includes additives generally used for resin compositions, for example, antioxidants, heat stabilizers, etc., as long as the object of the present invention is not impaired. Japanese agents, anti-blocking agents, tackifiers, antistatic agents, slip agents, nucleating agents, foaming agents, cross-linking agents, biomass resources, biodegradation accelerators and the like may be blended.

2. 2. Stretched base film / raw fabric manufacturing method and manufacturing conditions The stretched base film can be obtained by stretching the raw fabric. Examples of the method for manufacturing the raw fabric include inflation molding, T-die molding, and calendar molding, but inflation molding or T-die molding is preferable from the viewpoint of production speed, ease of manufacturing, and the like.
The production conditions of the raw fabric are not particularly limited, but the thickness of the raw fabric film is preferably 20 μm to 200 μm. It is more preferably 30 μm to 200 μm, and even more preferably 50 μm to 200 μm.

-Stretching method The stretched base film may be a uniaxially stretched film or a biaxially stretched film. As the stretching method, any of longitudinal uniaxial stretching, horizontal uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching can be used.

-Vertical stretch ratio The stretch ratio of the stretched base film in the mechanical direction (MD) is preferably 2 times or more and 15 times or less, and preferably 5 times or more and 10 times or less. Further, it is preferable that the value is 7 times or more.
By increasing the draw ratio of the stretched base film in the mechanical direction (MD), the strength and heat resistance of the laminate of the present invention can be improved. Further, the printability on the substrate can be improved. Further, since the transparency of the base material can be improved, the visibility can be improved when an image is formed on the surface of the base material on the heat-sealed layer side. On the other hand, the upper limit of the draw ratio in the mechanical direction (MD) of the stretched base film is not particularly limited, but is 15 times or less, and further 10 times or less from the viewpoint of the breaking limit of the stretched film. Is preferable.

Transverse stretch ratio The stretch ratio of the TD of the stretched base film is preferably 1.5 times or more, and more preferably 2 times or more.
By setting the draw ratio of the TD of the stretched base film to 1.5 times or more, the strength and heat resistance of the laminate of the present invention can be improved. Further, the printability on the substrate can be improved. Further, since the transparency of the base material can be improved, the visibility can be improved when an image is formed on the surface of the base material on the heat-sealed layer side. On the other hand, the upper limit of the draw ratio of the TD of the stretched base film is not particularly limited, but is preferably 10 times or less from the viewpoint of the breaking limit of the stretched film.

-Biaxial stretching ratio When the stretched base film is stretched to MD and TD, it is preferably 1.5 times or more, more preferably 2 times or more, respectively.
By increasing the draw ratios of MD and TD of the stretched base film, the strength and heat resistance of the laminate of the present invention can be improved. Further, the printability on the substrate can be improved. Further, since the transparency of the base material can be improved, the visibility can be improved when an image is formed on the surface of the base material on the heat-sealed layer side. On the other hand, the upper limit of the draw ratios of the MD and TD of the stretched base film is not particularly limited, but the lower limit of the draw ratios of the MD and TD is set from the viewpoint of the breaking point limit of the stretched base film. It is preferably 5 times, preferably 2 times, and the product of the MD stretching ratio and the TD stretching ratio is preferably 50 or less.

-Rigidity The elastic modulus with reference to JIS K7127 is used as an index of the rigidity of the stretched base film. When the tensile elastic modulus in the mechanical direction (MD) is EM and the tensile elastic modulus in the orthogonal direction (TD) is ET, both are preferably present in a specific region. In order to use the stretched film as a base material, it is necessary to have an appropriate hardness when used as a film packaging material and a certain rigidity, that is, an elastic modulus from the viewpoint that the image does not shift during printing. That is, when EM, ET, or both are present outside a specific region, it is not preferable because the film packaging material does not have an appropriate hardness and the image may shift during printing.
That is, the EM and the ET of the stretched film obtained by stretching the polyethylene resin composition for a stretched base film of the present invention by inflation molding or T-die molding 7 times to MD. A polyethylene resin composition for a stretched base film, which is characterized by being present in a region satisfying the following formulas (1), (2) and (3), is preferable.
(1) ET ≧ 1500
(2) EM ≧ ET-400
(3) EM ≤ 3ET
Such a suitable range is the range surrounded by the line shown in FIG.
Considering sufficient rigidity as a stretched base film and a rigidity balance of MD and TD, ET is preferably 1600 MPa or more, more preferably 2000 MPa or more while satisfying the formulas (1), (2) and (3). Further preferably, the EM is also preferably 1500 MPa or more, preferably 1600 MPa or more, still more preferably 2000 MPa or more. The upper limit of ET is not particularly limited, but is preferably 8000 MPa or less, and more preferably 7,000 MPa or less. The upper limit of EM is not particularly limited, but is preferably 8000 MPa or less, and more preferably 7000 MPa or less.

Moisture vapor transmission rate The water vapor transmission rate of the stretched base film is not particularly limited, but 9.0 g / m ² · day is preferable, and 8.0 g is preferable for the stretched film 7-fold stretched from the original fabric of 150 μm to MD. It is more preferably less than / m ² · day.
The water vapor barrier property of polyethylene to various gases tends to increase as the density increases. Further, in the same polyethylene resin composition, a stretched film having the same thickness has better water vapor barrier property than a film before stretching obtained by inflation molding or T-die molding. Therefore, a stretched base film using a high-density polyethylene resin composition is preferable because it has an excellent water vapor barrier property.

-Surface treatment It is preferable that the stretched base film is surface-treated. This makes it possible to improve the adhesion with the adjacent layer.
The surface treatment method is not particularly limited, for example, corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas and / or nitrogen gas, physical treatment such as glow discharge treatment, and oxidation using chemicals. Examples include chemical treatment such as treatment.
Further, an anchor coat layer may be formed on the surface of the base material by using a conventionally known anchor coat agent.

Images such as characters, patterns, and symbols may be formed on at least one surface of the stretched base film. Since deterioration of the image over time can be prevented, it is preferable that the image is formed on the side where the heat-sealing polyethylene layer of the stretched base film is laminated.
The method for forming an image is not particularly limited, and examples thereof include conventionally known printing methods such as a gravure printing method, an offset printing method, and a flexographic printing method. Among these, the flexographic printing method is preferable from the viewpoint of environmental load.

-Evaporation film A vapor deposition film may be provided on at least one surface of the stretched base film. As the vapor deposition film, a vapor deposition film composed of a metal such as aluminum and an inorganic oxide such as aluminum oxide, silicon oxide, magsium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide and barium oxide is used. Can be mentioned.

The thickness of the vapor-film vapor film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and further preferably 10 nm or more and 40 nm or less.
By setting the thickness of the thin-film film to 1 nm or more, the oxygen barrier property and the water vapor barrier property of the laminate of the present invention can be further improved. Further, by setting the thickness of the thin-film vapor film to 150 nm or less, it is possible to prevent the occurrence of cracks in the thin-film film and improve the recyclability of the laminate of the present invention.

When the vapor-deposited film is an aluminum-deposited film, its OD value is preferably 2 or more and 3.5 or less. Thereby, the oxygen barrier property and the water vapor barrier property can be improved while maintaining the productivity of the laminate of the present invention. In the present invention, the OD value can be measured according to JIS-K-7361.

The vapor deposition film can be formed by using a conventionally known method, for example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method and an ion plating method, and plasma chemistry. Examples thereof include chemical vapor deposition methods (CVD methods, CVD methods) such as a vapor phase growth method, a thermochemical vapor phase growth method, and a photochemical vapor deposition method.

Further, for example, both the physical vapor deposition method and the chemical vapor deposition method can be used in combination to form a composite film composed of two or more layers of vapor-filmed films of different kinds of inorganic oxides. The degree of vacuum of the vapor deposition chamber is preferably about ^10-2 to ^10-8 mbar before the introduction of oxygen, and preferably about 10-1 to ^{10-6 mbar} after the introduction of oxygen. The amount of oxygen introduced differs depending on the size of the vapor deposition machine and the like. As the oxygen to be introduced, an inert gas such as argon gas, helium gas, or nitrogen gas may be used as the carrier gas within a range that does not hinder. The transport speed of the film can be about 10 to 800 m / min.

It is preferable that the surface of the thin-film film is subjected to the above surface treatment. This makes it possible to improve the adhesion with the adjacent layer.

The stretched base film of the present invention means a stretched film used as a base material of a resin laminate.
The stretched base film of the present invention may be provided with a heat-resistant coat layer or a barrier coat layer as a coat layer on at least one surface, and contains at least one resin material. Examples of the resin material of the coat layer include polyester, polyolefin, cellulose resin, (meth) acrylic resin, urethane resin and vinyl resin.

The ratio of the resin material contained in the coat layer to the sum of the resin materials contained in the laminate is preferably 3% by mass or less, and more preferably 1% by mass or less. This makes it possible to improve heat resistance and barrier properties while maintaining the recyclability of the laminate of the present invention.

The thickness of the coat layer is preferably 0.1 μm or more and 5 μm or less, and more preferably 0.5 μm or more and 3 μm or less. Thereby, the heat resistance and the barrier property can be improved while maintaining the recyclability of the laminate obtained by using the stretched base film of the present invention.

3. 3. Resin Laminated / Multilayer Stretched Film In addition to the base material made of a stretched base film made of a polyethylene resin composition satisfying the requirements of the present invention, it is made of at least one polyethylene resin composition and is inflation-molded or T. The film obtained by die molding may be a film in which a layer made of a further stretched film is laminated.
Examples of the resin that can be used include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and ultra low density polyethylene (ULDPE). Further, as a laminating method, the co-pressing film obtained by co-pressing may be further stretched, or the films may be bonded to each other using an adhesive.

A resin laminate containing a layer made of a stretched base film as a base material and a polyethylene-based resin sealant as a sealant layer may be used.

The layer constituting the resin laminate may be a resin laminate made entirely of polyethylene-based resin. This resin laminate can be treated as a monomaterial resin laminate. The ratio of the main component in the monomaterial resin laminate is not particularly limited, but is preferably 70% by weight, more preferably 80% by weight.

-Adhesive Since the above resin laminate is laminated, an adhesive can be used. The adhesive used contains at least one resin composition, but is not particularly limited. Adhesives that can be used include, for example, epoxy-based, acrylic-based, and urethane-based adhesives.
The adhesive containing any of the above resin compositions is not particularly limited, but a one-component type, a two-component type, or a hot melt type can be used as needed.
In addition, if a barrier adhesive such as DIC Corporation, product name: PASLIM or Mitsubishi Gas Chemical Company, product name: Maxive is used, the amount of other barrier materials used can be reduced, and the resin laminate can be used. It is preferable because the ratio of polyethylene increases.

4. Packaging Material The laminate of the present invention can be particularly suitably used for packaging material applications. The shape of the packaging material is not particularly limited and may be a packaging bag or a stand pouch. In the stand pouch, even if only the body is formed of the resin laminate or only the bottom is formed of the resin laminate, both the body and the bottom are formed of the resin laminate. May be.

-Packaging bag A bag-shaped packaging material can be manufactured by folding the laminate in half so that the sealant layer (heat seal layer) is on the inside, stacking the layers, and heat-sealing the ends thereof. ..
The bag-shaped packaging material can also be manufactured by stacking two laminated bodies so that the heat-sealing layers face each other and heat-sealing the ends thereof.

-Stand pouch The stand pouch-shaped packaging material is heat-sealed in a tubular shape so that the heat-seal layer of the laminate is on the inside to form the body, and then the heat-seal layer is on the inside. The laminated body can be manufactured by folding it into a V shape, sandwiching it from one end of the body portion, and heat-sealing it to form a bottom portion.

The heat sealing method is not particularly limited, and for example, a known method such as a bar seal, a rotary roll seal, a belt seal, an impulse seal, a high frequency seal, and an ultrasonic seal can be used.

The contents to be filled in the packaging material are not particularly limited, and the contents may be liquid, powder or gel. Further, it may be food or non-food.
After filling the contents, the opening can be heat-sealed to form a package.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The evaluations and resins used in Examples and Comparative Examples are as follows.

<Evaluation method>
(1) Density Measured according to JIS K6922-1 and 2.
(2) MFR
Measurements were made in accordance with JIS K6922-2 under the conditions of 190 ° C. and a 2.16 kg load.
(3) Molecular weight distribution The molecular weight (number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz)) is measured by GPC measurement, and the molecular weight distribution [weight average molecular weight (Mw) and number average molecular weight (Mn)). Ratio (Mw / Mn)] was calculated.
(4) Melt tension Using a capillograph manufactured by Toyo Seiki Seisakusho, a resin heated and stabilized at 190 ° C. in a furnace is extruded from an orifice with an inner diameter of 2.095 mm and a length of 8 mm at a piston speed of 1 cm / min, and the extruded molten resin. Was pulled at a speed of 4 m / min, and the resistance generated at that time was measured and used as the melt tension value.
(5) Tensile elastic modulus Measured with reference to JIS K7127. When a test piece with a length of 200 mm and a width of 10 mm is cut in the machine direction (MD direction) and the direction perpendicular to the film (TD direction), the tensile speed is 2 mm / min, the chuck distance is 100 mm, and the elastic modulus is 1%. The tensile modulus was measured.

<Method of making resin and stretched film>
A stretched base film was prepared using the following resins. Since the preheating temperature and the stretching temperature at the time of stretching are related to the melting point of the resin, they are appropriately adjusted.

[Example 1]
High-density polyethylene (P1) manufactured by Japan Polyethylene Corporation, trade name Novatec HD, high-density polyethylene, grade name: HY444, MFR = 1.1 g / 10 min, density = 0.956 g / cm ³ was prepared.
A film of 150 μm was prepared from this high-density polyethylene (P1) at 190 ° C. with an inflation molding machine and a blow ratio of 2.2.
Next, the obtained film was subjected to a longitudinal stretching device of a high-temperature sequential biaxial stretching device manufactured by Ichikin Kogyo Co., Ltd., with a feeding speed of 1.0 m / min, a preheating temperature of 120 ° C., a stretching temperature of 129 ° C., and a cooling temperature of 30. A stretched base film was obtained by stretching at a temperature of 7 times and a stretching ratio of 7 times.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Example 2]
Instead of the high-density polyethylene (P1) used in Example 1, Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY350, MFR = 2.5 g / 10 min, density = 0.952 g / A film was prepared and stretched in the same manner as in Example 1 except that high-density polyethylene (P2) of cm ³ was prepared to obtain a stretched base film.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Example 3]
Instead of the high-density polyethylene (P1) used in Example 1, Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY430, MFR = 0.8 g / 10 min, density = 0.955 g / A high-density polyethylene (P3) of cm ³ was prepared, and a film was prepared and stretched by the same method as in Example 1 except that the stretching temperature was 131 ° C. to obtain a stretched base film.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Example 4]
Instead of the high-density polyethylene (P3) used in Example 3, Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY531, MFR = 0.5 g / 10 min, density = 0.958 g / A film was prepared and stretched in the same manner as in Example 3 except that high-density polyethylene (P4) of cm ³ was prepared to obtain a stretched base film.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Example 5]
Instead of the high-density polyethylene used in Example 3, Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY540, MFR = 0.9 g / 10 min, density = 0.960 g / cm ³ A film was prepared and stretched in the same manner as in Example 3 except that high-density polyethylene (P5) was prepared to obtain a stretched base film.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Comparative Example 1]
A product manufactured by Japan Polyethylene Corporation, trade name Novatec LD, high-pressure radical method low-density polyethylene (Q1), grade name: LF240, MFR = 0.7 / 10min, density = 0.924 g / cm ³ was prepared.
A film of 150 μm was prepared from this low-density polyethylene at 180 ° C. with an inflation molding machine and a blow ratio of 2.2.
Next, the obtained film was subjected to a longitudinal stretching device of a high-temperature sequential biaxial stretching device manufactured by Ichikin Kogyo Co., Ltd., with a feeding speed of 1.0 m / min, a preheating temperature of 100 ° C., a stretching temperature of 100 ° C., and a cooling temperature of 30. A stretched base film was obtained by stretching at a temperature of 4 times and a stretching ratio of 4 times.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Comparative Example 2]
Made by Japan Polyethylene Corporation, trade name Novatec LL, linear low density polyethylene (Q2), grade name: UF421, MFR = 0.9 g / 10 min, density = 0.926 g / cm ³ were prepared.
A film of 150 μm was prepared from this linear low-density polyethylene at 190 ° C. with an inflation molding machine and a blow ratio of 2.2.
Next, the film was obtained by a longitudinal stretching device of a high-temperature sequential biaxial stretching device manufactured by Ichikin Kogyo Co., Ltd., with a feeding speed of 1.0 m / min, a preheating temperature of 100 ° C, a stretching temperature of 110 ° C, and a cooling temperature of 30 ° C. , Stretched at a stretching ratio of 7 times to obtain a stretched base film.
Table 1 shows other physical characteristics of the resin and the results of each item.
[Comparative Example 3]
Instead of the high-density polyethylene used in Example 1, Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene (Q3), grade name: HF335, MFR = 0.6 g / 10 min, density = 0.949 g / A film was prepared and stretched in the same manner as in Example 1 except that cm ³ was prepared, to obtain a stretched base film.
Table 1 shows other physical characteristics of the resin and the results of each item.

<Evaluation>
-Stretchability The maximum magnification in Table 1 is an evaluation index for stretchability. The maximum magnification is the maximum stretching ratio at which the film can be obtained without breaking by increasing the stretching ratio of the film. The maximum magnification of Examples 1 to 5 was 9 times or more stretchable because the value of MT satisfied the requirements of the present invention, but in Comparative Example 1, MT did not satisfy the requirements of the present invention. It can be said that the polyethylene resin composition of the present invention is excellent in stretchability because it can be stretched only up to 4 times.

-Rigidity EM and ET in Table 1 are evaluation indexes of rigidity. Since the EM and ET of Examples 1 to 5 satisfy the requirements of the present invention, a high-rigidity film is obtained. On the other hand, in Comparative Example 2, the density does not satisfy the requirements of the present invention, and in Comparative Example 3, the rigidity is not high because the molecular weight distribution (Mw / Mn) does not satisfy the requirements of the present invention. Therefore, the polyethylene resin of the present invention is used. It can be said that the composition has excellent rigidity.

Claims (9)

A polyethylene resin composition for a stretched base film used as a base material of a resin laminate, which is characterized by satisfying the following physical properties (a-1) to (a-4). Composition.
(A-1) The density is 0.935 to 0.970 g / cm ³ , (a-2) the melt flow rate (MFR) at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 7 g / 10 min (a-1). a-3) The value of melt tension (MT) at 190 ° C. is 8.0 g or less (a-4) Molecular weight distribution by gel permeation chromatography (GPC) [weight average molecular weight (Mw) and number average molecular weight (Mn) )] Is 1.5 to 10.0. Mechanical direction (MD) tension of the film obtained by stretching the polyethylene resin composition for a stretched base film according to claim 1 by inflation molding or T-die molding 7 times in the MD direction. When the elastic coefficient is EM and the tensile elastic coefficient in the orthogonal direction (TD) is ET, the EM and the ET are present in the region satisfying the following formulas (1), (2) and (3). The polyethylene resin composition for a stretched base film according to claim 1, which is characterized.
(1) ET ≧ 1500
(2) EM ≧ ET-400
(3) EM ≤ 3ET A stretched base film obtained by stretching a film obtained by inflation molding or T-die molding using the polyethylene resin composition for a stretched base film according to claim 1 or 2. A stretched base film obtained by stretching a film obtained by inflation molding or T-die molding using the polyethylene resin composition for a stretched base film according to claim 1 or 2 to MD 7 times or more. A stretched base material obtained by stretching a film obtained by inflation molding or T-die molding using the polyethylene resin composition for a stretched base film according to claim 1 or 2 to MD and TD more than twice. the film. A resin laminate containing a layer made of the stretched base film according to any one of claims 3 to 5. The resin laminate according to claim 6, wherein the layer made of the stretched base film according to any one of claims 3 to 5 is included as a base material, and the polyethylene-based resin sealant layer is included as a sealant layer. The resin laminate according to claim 6 or 7, wherein the layers constituting the resin laminate are all monomaterial resin laminates made of polyethylene-based resin. A packaging material using the resin laminate according to any one of claims 6 to 8.

Images