Polyethylene resin composition for stretched base film and stretched base film made from the same

Abstract

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

Description

Technical Field

[0001] 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 same, a laminate containing the stretched base film, and a packaging material composed of the laminate.

Background Art

[0002] Conventionally, as one of the basic configurations of a packaging material, there is a structure in which a heat-sealing layer and a base material layer are bonded together with an adhesive. Among these, as the heat-sealing layer, a film made of a polyethylene resin composition having appropriate flexibility, transparency, and excellent heat-sealing properties is widely used. 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 viewpoints of rigidity, impact resistance, and heat resistance (see Patent Document 1).

[0003] In recent years, with the increasing demand for building a recycling-oriented society, there is a need for packaging materials with high recyclability. However, conventional packaging materials are composed of different resin materials as described above, and it is difficult to separate them for each resin material, so they are not recycled at present.

[0004] As a method for providing high recyclability, there is a method of constructing 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 in which both the heat-sealing layer and the base material layer are made of films made of polyethylene resin compositions are expected as highly recyclable packaging materials for realizing a recycling-oriented society.

[0005] However, when using a film made of a polyethylene resin composition 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 is the strength of the packaging material insufficient, but also the film stretches during printing and the image shifts. To compensate for this, a film obtained by stretching a film formed from a polyethylene resin composition by the inflation molding method or the T-die molding method is used. As a polyethylene resin composition for a stretched film, for example, a resin composition obtained by blending LLDPE and HDPE (refer to Patent Document 2) or LLDPE having a specific crystal component (refer to Patent Document 3) has been proposed. However, since both are polyethylene resin compositions for shrink film applications rather than for use as a base material, the development of a polyethylene resin composition for a stretching base material has been desired.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a polyethylene resin composition for a stretching base material that is excellent in stretchability and rigidity and is suitable as a stretching base material, and a resin laminate and a packaging material using the same.

Means for Solving the Problems

[0008] As a result of intensive research to solve the above problems, the inventors of the present invention molded a film by inflation molding using a polyethylene resin composition satisfying specific conditions, and stretched the obtained film with a hot roll stretching machine. As a result, it was found that the film exhibited characteristics capable of solving the above problems, and based on these findings, the inventors completed the present invention.

[0009] 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 is (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 the melt tension (MT) at 190 ° C is 8.0 g or less. (a-4) The molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)] by gel permeation chromatography (GPC) is 1.5 to 10.0.

[0010] Further, according to the present invention [2], when the film obtained by stretching the film obtained by inflation molding or T-die molding of the polyethylene resin composition in the first invention is stretched 7-fold in the machine direction (MD), the tensile elastic modulus in the machine direction (MD) of the film is EM, and the tensile elastic modulus in the orthogonal direction (TD) is ET, a polyethylene resin composition is provided which is characterized by being present within a region satisfying the formulas (1), (2), and (3). (1) ET ≧ 1500 (2) EM ≧ ET - 400 (3) EM ≦ 3ET

[0011] Further, according to the present invention [3], there is provided a stretched base film 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.

[0012] According to the present invention [4], there is provided a stretched base film 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 by 7 times or more in the MD direction.

[0013] According to the present invention [5], there is provided a stretched base film 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 by 2 times or more in both the MD and TD directions.

[0014] According to the present invention [6], there is provided a resin laminate including a layer made of the stretched base film described in any one of the third to fifth inventions.

[0015] According to the present invention [7], there is provided a resin laminate including, as a base material, a layer made of the stretched base film described in any one of the third to fifth inventions and including a polyethylene-based resin sealant layer as a sealant layer.

[0016] According to the present invention [8], there is provided a monomaterial resin laminate in which the resin laminate described in the sixth or seventh invention is entirely composed of a polyethylene-based resin.

[0017] According to the present invention [9], there is provided a packaging material using the resin laminate described in the sixth to eighth inventions.

Advantages of the Invention

[0018] The polyethylene resin composition of the present invention can provide a stretched base film excellent in stretchability and rigidity. Since printing on the surface of such a stretched base film is also possible, by using the stretched base film as a base material for a packaging material and laminating it with a polyethylene sealant film, a highly recyclable packaging material, particularly a monomaterial laminate and packaging material composed of a single material, can be provided.

Brief Description of the Drawings

[0019]

Figure 1

Embodiments for Carrying Out the Invention

[0020] The present invention relates to a polyethylene resin composition for a stretched base film and a stretched base film made therefrom. Hereinafter, the present invention will be described in detail item by item. The stretched base film of the present invention means 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 stretched film used as a base material of a resin laminate.

[0021] 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 single polyethylene resin or a mixture of polyethylene resins thereof, and additives necessary therefor may be added thereto. · Polymerization catalyst and polymerization method of polyethylene resin composition The polyethylene resin constituting the polyethylene resin composition is produced using a conventionally known catalyst such as a Ziegler-Natta catalyst, a Phillips catalyst, a metallocene catalyst, etc., using either ethylene derived from a petroleum raw material or ethylene derived from a biomass raw material, or both as raw materials. Preferably, it is a Ziegler-Natta catalyst or a metallocene catalyst. Generally, these catalysts are in a state where a complex composed of an organometallic compound is supported on a carrier such as silica or an Mg compound. The polymerization method can be any of the solution method, the slurry method, and the gas phase method, preferably the slurry method and the gas phase method. 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 exists as a slurry in the solvent. Depending on the shape of the reaction vessel, it can be roughly classified into two types: the autoclave method and the loop pipe method. The gas phase method is a polymerization method in which ethylene, an α-olefin as a comonomer, and hydrogen as a chain transfer agent are fed in a gaseous state from the lower part of a vertical reaction vessel, and a polymerization catalyst is introduced thereinto. (Compiled by Kazuo Matsuura and Takataka Mikami / From the Polyethylene Technology Reader)

[0022] ·Polymerization method of polyethylene resin composition using the slurry method In addition, both the autoclave method and the loop pipe method of the slurry method can perform single-stage polymerization and multi-stage polymerization. Multi-stage polymerization is a method in which polymerization is sequentially carried out in 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 further α-olefin is copolymerized to produce polyethylene that becomes a high molecular weight component, and then ethylene and hydrogen are introduced into the polymerization system. In the second stage, polyethylene that becomes a low molecular weight component is produced. As a result, polyethylene containing a high molecular weight component and a low molecular weight component can be prepared. Also, in the first stage, polyethylene that becomes a low molecular weight component and in the second stage, polyethylene that becomes a high molecular weight component may be produced. In the case of multi-stage polymerization, regarding the amount and properties of the polyethylene produced in the polymerization region after the second stage and later, the amount of polyethylene produced after each polymerization reactor (which can be grasped by unreacted gas analysis, etc.) is determined, and the physical properties of the polyethylene can be obtained by measuring the physical properties of the polymers withdrawn after each polymerization reactor and converting them from the additivity of the physical properties. The polyethylene resin compositions obtained by these production methods have various combinations of density, melt flow rate (MFR), melt tension (MT), and molecular weight distribution over a wide range in order to meet various conventionally known applications. Among them, the polyethylene resin composition for the stretched base film of the present invention is characterized by selecting and using a polyethylene resin having a specific density, melt flow rate (MFR), melt tension (MT), and molecular weight distribution.

[0023] · Comonomer composition of the polyethylene resin composition The polyethylene resin composition according to the present invention is a homopolymer of ethylene or a copolymer of ethylene and one or more α-olefins selected from α-olefins having 3 to 18 carbon atoms. As the α-olefin having 3 to 18 carbon atoms, those having 3 to 12 carbon atoms are preferable, and specifically, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. can be mentioned. Further, the total content of these α-olefins is usually selected in the range of 30 mol% or less, preferably 20 mol% or less. Within this range, the flexibility and heat resistance of films and the like are improved. Here, the content of the α-olefin is a value measured by the 13C-NMR method under the following conditions. Apparatus: JEOL-GSX270 manufactured by JEOL Concentration: 300 mg / 2 mL Solvent: ortho-dichlorobenzene

[0024] · Density The polyethylene resin composition for the stretched film of the present invention must have a density in the range of 0.935 to 0.970 g / cm 3 Preferably, the density is in the range of 0.940 to 0.965 g / cm 3 More preferably, it is in the range of 0.945 to 0.965 g / cm 3 Here, the density is a value measured in accordance with JIS K6922-1 and 2. When the density is 0.935 g / cm 3If it is less than this value, the rigidity of the stretched film for the substrate 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.

[0025] · Melt Flow Rate (MFR) The polyethylene resin composition must have an MFR 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, there is a risk of generation of gels or the like. On the other hand, if the MFR exceeds 7 g / 10 min, a stretched film for the substrate with 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, it is preferable because a stretched film for the substrate can be obtained without generation of gels or the like. Note that the MFR is the extrusion rate 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.

[0026] · Melt Tension (MT) The polyethylene resin composition must have an MT of 8.0 g or less. If the MT is larger than this value, the stretched film breaks at a low draw ratio during the production of the stretched film, which is not preferable. Note that the MT is the resistance generated when the resin heat-stabilized at 190 °C in the 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 is pulled at a speed of 4 m / min.

[0027] · Molecular Weight Distribution The polyethylene resin composition must have a molecular weight distribution (the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), Mw / Mn) in the range of 1.5 to 10.0. The preferred range of the Mw / Mn ratio is 2.0 to 9.0. When Mw / Mn exceeds 10.0, the resulting drawn film for the base material may have low rigidity and be an opaque film, which is not preferable. By using the polyethylene resin composition having an Mw / Mn in the range of 1.5 to 10.0, it is possible to obtain a base film optimal for the drawn base material film, which is preferable.

[0028] ·Resin blend In the present invention, the polyethylene resin composition may be single, but two or more kinds may be mixed to produce a polyethylene resin that simultaneously satisfies the above requirements, and it may also be used.

[0029] ·Additive In the polyethylene resin or resin composition according to the present invention, additives generally used for resin compositions, such as antioxidants, heat stabilizers, neutralizing agents, antiblocking agents, tackifiers, antistatic agents, slip agents, nucleating agents, foaming agents, crosslinking agents, biomass resources, biodegradation accelerators, etc., may be blended within a range that does not impair the object of the present invention.

[0030] 2. Drawn base material film ·Base film manufacturing method and manufacturing conditions The drawn base material film is obtained by drawing the base film. Examples of the manufacturing method of the base film include inflation molding, T-die molding method, or calendar molding method, but from the viewpoints of production speed and ease of manufacturing, inflation molding or T-die molding method is preferable. Also, the manufacturing conditions of the base film are not particularly limited, but the thickness of the base film is preferably 20 μm to 200 μm. More preferably, it is 30 μm to 200 μm, and even more preferably, it is 50 μm to 200 μm.

[0031] ·Drawing 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, transverse uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching can be used.

[0032] · Longitudinal stretching ratio The stretching ratio in the machine direction (MD) of the stretched base film is preferably 2 times or more and 15 times or less, more preferably 5 times or more and 10 times or less. Further, it is preferably 7 times or more. By increasing the stretching ratio in the machine direction (MD) 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 base material can be improved. In addition, since the transparency of the base material can be improved, when an image is formed on the surface of the base material on the heat seal layer side, the visibility thereof can be improved. On the other hand, the upper limit value of the stretching ratio in the machine direction (MD) of the stretched base film is not particularly limited, but from the viewpoint of the breaking limit of the stretched film, it is preferably 15 times or less, more preferably 10 times or less.

[0033] · Transverse stretching ratio The stretching ratio in the TD of the stretched base film is preferably 1.5 times or more, more preferably 2 times or more. By setting the stretching ratio in 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 base material can be improved. In addition, since the transparency of the base material can be improved, when an image is formed on the surface of the base material on the heat seal layer side, the visibility thereof can be improved. On the other hand, the upper limit value of the stretching ratio in the TD of the stretched base film is not particularly limited, but from the viewpoint of the breaking limit of the stretched film, it is preferably 10 times or less.

[0034] · Biaxial stretching ratio When the stretched base film is stretched in the MD and TD, each is preferably 1.5 times or more, more preferably 2 times or more. By increasing the draw ratios in the machine direction (MD) and the transverse direction (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 base material can be improved. In addition, since the transparency of the base material can be improved, when an image is formed on the surface of the base material on the heat seal layer side, its visibility can be improved. On the other hand, the upper limits of the draw ratios in the MD and TD of the stretched base film are not particularly limited, but from the viewpoint of the breaking point limit of the stretched base film, the lower limit values of the draw ratios in the MD and TD are 1.5 times, preferably 2 times, and it is preferable that the product of the MD draw ratio and the TD draw ratio is 50 or less.

[0035] ·Rigidity As an index of the rigidity of the stretched base film, the elastic modulus referring to JIS K7127 is used. When the tensile elastic modulus in the machine direction (MD) is EM and the tensile elastic modulus in the orthogonal direction (TD) is ET, it is preferable that both are present within a specific region. In order to use the stretched film as a base material, a certain rigidity, that is, an elastic modulus is required from the viewpoints of appropriate hardness when used as a film packaging material and no image shift during printing. That is, when EM or ET, or both are outside the specific region, it is not preferable because there is no appropriate hardness when used as a film packaging material and the image may shift during printing. That is, it is preferable that the polyethylene resin composition for a stretched base film of the present invention satisfies the following formulas (1), (2), and (3) in the region where the EM and the ET of the stretched film obtained by stretching the original film obtained by inflation molding or T-die molding the polyethylene resin composition for a stretched base film 7 times in the MD. (1) ET ≥ 1500 (2) EM ≥ ET - 400 (3) EM ≤ 3ET Such a preferable range is the range surrounded by the line shown in FIG. 1. Considering sufficient rigidity as an extended base material film and the rigidity balance between MD and TD, more preferably, while satisfying formulas (1), (2), and (3), ET is preferably 1600 MPa or more, more preferably 2000 MPa or more, and even more preferably EM is also 1500 MPa or more, preferably 1600 MPa or more, and more preferably 2000 MPa or more. The upper limit of ET is not particularly limited, but 8000 MPa or less is preferable, and 7000 MPa or less is more preferable. The upper limit of EM is not particularly limited either, but 8000 MPa or less is preferable, and 7000 MPa or less is more preferable.

[0036] ·Water vapor permeability The water vapor permeability of the extended base material film is not particularly limited, but in an extended film stretched 7 times in the MD direction from a raw sheet of 150 μm, 9.0 g / m 2 ·day is preferable, and 8.0 g / m 2 ·day or less is more preferable. The water vapor barrier property of various gases in polyethylene tends to increase as the density increases. Furthermore, in the same polyethylene resin composition, the extended film with the same thickness has better water vapor barrier property than the pre-stretched film obtained by inflation molding or T-die molding. Therefore, it is preferable to use an extended base material film made of a polyethylene resin composition with a high density because it has excellent water vapor barrier property.

[0037] ·Surface treatment The extended base material film is preferably subjected to surface treatment. Thereby, the adhesion with an adjacent layer can be improved. The method of surface treatment is not particularly limited, and examples include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemical agents. Also, an anchor coat layer may be formed on the surface of the base material using a conventionally known anchor coat agent.

[0038] The stretched base film may have images such as characters, patterns, symbols, etc. formed on at least one surface thereof. Since it is possible to prevent the deterioration of the images over time, it is preferable that the images are formed on the side where the heat-sealable polyethylene layer of the stretched base film is laminated. The method for forming the image is not particularly limited, and examples thereof include conventionally known printing methods such as the gravure printing method, the offset printing method, and the flexographic printing method. Among these, from the viewpoint of environmental load, the flexographic printing method is preferable.

[0039] ·Vapor deposition film The stretched base film may be provided with a vapor deposition film on at least one surface thereof. Examples of the vapor deposition film include vapor deposition films composed of metals such as aluminum and inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

[0040] Further, the thickness of the vapor deposition film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less. By setting the thickness of the vapor deposition 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 vapor deposition film to 150 nm or less, the generation of cracks in the vapor deposition film can be prevented, and the recyclability of the laminate of the present invention can be improved.

[0041] When the vapor deposition film is an aluminum vapor deposition 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 in accordance with JIS-K-7361.

[0042] The vapor deposition film can be formed by a conventionally known method, for example, physical vapor deposition methods such as vacuum vapor deposition method, sputtering method and ion plating method (Physical Vapor Deposition method, PVD method), and chemical vapor deposition methods such as plasma chemical vapor deposition method, thermal chemical vapor deposition method and photo chemical vapor deposition method (Chemical Vapor Deposition method, CVD method), etc. can be mentioned.

[0043] Also, for example, it is also possible to form and use a composite film composed of two or more layers of vapor deposition films of different inorganic oxides by using both physical vapor deposition method and chemical vapor deposition method in combination. As for the degree of vacuum in the vapor deposition chamber, before introducing oxygen, it is preferably about 10 -2 ~10 -8 mbar, and after introducing oxygen, it is preferably about 10 -1 ~10 -6 mbar. Note that the amount of oxygen introduced etc. varies depending on the size of the vapor deposition machine etc. As the oxygen to be introduced, inert gases such as argon gas, helium gas, nitrogen gas etc. may be used as carrier gas within a non-obstructing range. The conveyance speed of the film can be about 10 to 800 m / min.

[0044] The surface of the vapor deposition film is preferably subjected to the above surface treatment. Thereby, the adhesiveness with the adjacent layer can be improved.

[0045] 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 can 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 kind of resin material. Examples of the resin material of the coat layer include polyester, polyolefin, cellulose resin, (meth)acrylic resin, urethane resin and vinyl resin etc.

[0046] 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, more preferably 1% by mass or less. Thereby, while maintaining the recyclability of the laminate of the present invention, the heat resistance and barrier properties can be improved.

[0047] The thickness of the coat layer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.5 μm or more and 3 μm or less. Thereby, while maintaining the recyclability of the laminate obtained using the stretched base film of the present invention, the heat resistance and barrier properties can be improved.

[0048] 3. Resin laminate · Multilayer stretched film In addition to the base material composed of a stretched base film composed of a polyethylene resin composition that satisfies the requirements of the present invention, a film composed of at least one or more polyethylene resin compositions and further stretched, obtained by inflation molding or T-die molding, may be laminated. Examples of resins 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). Also, as the lamination method, a coextruded film obtained by coextrusion molding may be further stretched, or films may be adhered to each other using an adhesive.

[0049] A resin laminate may be used that includes a layer composed of a stretched base film as a base material and a polyethylene-based resin sealant as a sealant layer.

[0050] The layers constituting the resin laminate may all be made of a polyethylene-based resin, and 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.

[0051] ·Adhesive An adhesive can be used to laminate the above resin laminate. The adhesive to be used contains at least one resin composition, but there is no particular limitation. Examples of the adhesive that can be used include epoxy-based, acrylic-based, and urethane-based adhesives. In addition, the adhesive containing any of the above resin compositions is not particularly limited, but a one-component type, two-component type, or hot melt type can be used as required. Also, when using an adhesive with barrier properties such as PASLIM manufactured by DIC Corporation and Macseal manufactured by Mitsubishi Gas Chemical Company, Inc., the amount of other barrier materials used can be reduced, and the ratio of polyethylene in the resin laminate increases, which is preferable.

[0052] 4. Packaging material The laminate of the present invention can be particularly preferably used for packaging materials. The shape of the packaging material is not particularly limited and may be a packaging bag or a stand-up pouch. In the case of a stand-up pouch, only the body, only the bottom, or both the body and the bottom may be formed of the above resin laminate.

[0053] ·Packaging bag The bag-shaped packaging material can be manufactured by folding the laminate in half so that the sealant layer (heat seal layer) of the laminate is on the inside, overlapping them, and heat-sealing the ends. Also, the bag-shaped packaging material can also be manufactured by overlapping two laminates so that the heat seal layers face each other and heat-sealing the ends.

[0054] ·Stand-up pouch The stand-up pouch-shaped packaging material can be manufactured by heat-sealing the laminate in a tubular shape so that the heat seal layer of the laminate is on the inside to form the body, and then folding the laminate in a V shape so that the heat seal layer is on the inside, sandwiching it from one end of the body, and heat-sealing to form the bottom.

[0055] The heat-sealing method is not particularly limited, and for example, it can be carried out by known methods such as bar-sealing, rotary roll-sealing, belt-sealing, impulse-sealing, high-frequency sealing, ultrasonic sealing, etc.

[0056] The contents filled in the packaging material are not particularly limited, and the contents may be liquids, powders, and gels. Also, they may be foods or non-foods. After filling the contents, the opening can be heat-sealed to form a package.

Examples

[0057] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. The evaluations and resins used in the examples and comparative examples are as follows.

[0058] <Evaluation method> (1) Density It was measured in accordance with JIS K6922-1 and 2. (2) MFR It was measured under the conditions of 190 °C and a load of 2.16 kg in accordance with JIS K6922-2. (3) Molecular weight distribution By GPC measurement, the molecular weights (number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz)) were measured, and the molecular weight distribution [the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn)] was calculated. (4) Melt tension Using a Capillograph manufactured by Toyo Seiki Seisaku-sho, Ltd., a resin heated and stabilized at 190 °C in a furnace was 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 to obtain the melt tension value. (5) Tensile modulus Measured with reference to JIS K7127. Test pieces with a size of 200 mm in length and 10 mm in width were cut in the machine direction (MD direction) and the transverse direction (TD direction) of the film, and the tensile elastic modulus at an elongation rate of 1% was measured with a tensile speed of 2 mm / min and a chuck distance of 100 mm.

[0059] <Method for producing used resin and stretched film> The stretched base film was produced using the following resins. Note that the preheating temperature and the stretching temperature during stretching were appropriately adjusted because they are related to the melting point of the resin. [Example 1] High-density polyethylene (P1) manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY444, MFR = 1.1 g / 10 min, density = 0.956 g / cm 3 was prepared. This high-density polyethylene (P1) was formed into a 150-μm film at 190°C and a blow ratio of 2.2 using an inflation molding machine. Next, the obtained film was stretched in the longitudinal stretching device of a high-temperature type sequential biaxial stretching device manufactured by Ichikin Kogyo Co., Ltd. at a draw-off speed of 1.0 m / min, a preheating temperature of 120°C, a stretching temperature of 129°C, a cooling temperature of 30°C, and a stretching ratio of 7 times to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Example 2] Except that high-density polyethylene (P2) manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY350, MFR = 2.5 g / 10 min, density = 0.952 g / cm 3 was prepared instead of the high-density polyethylene (P1) used in Example 1, the film was produced and stretched in the same manner as in Example 1 to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Example 3] Except that high-density polyethylene (P3) manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade name: HY430, MFR = 0.8 g / 10 min, density = 0.955 g / cm3 High-density polyethylene (P3) was prepared, and a film was formed and stretched in the same manner as in Example 1 except that the stretching temperature was 131°C to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Example 4] Instead of the high-density polyethylene (P3) used in Example 3, high-density polyethylene, grade name: HY531, MFR = 0.5 g / 10 min, density = 0.958 g / cm, trade name Novatec HD, manufactured by Nippon Polyethylene Co., Ltd. 3 A film was formed and stretched in the same manner as in Example 3 except that high-density polyethylene (P4) was prepared to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Example 5] Instead of the high-density polyethylene used in Example 3, high-density polyethylene, grade name: HY540, MFR = 0.9 g / 10 min, density = 0.960 g / cm, trade name Novatec HD, manufactured by Nippon Polyethylene Co., Ltd. 3 A film was formed and stretched in the same manner as in Example 3 except that high-density polyethylene (P5) was prepared to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Comparative Example 1] High-pressure radical method low-density polyethylene (Q1), grade name: LF240, MFR = 0.7 / 10 min, density = 0.924 g / cm, trade name Novatec LD, manufactured by Nippon Polyethylene Co., Ltd. 3 was prepared. This low-density polyethylene was formed into a 150-μm film at 180°C with a blow ratio of 2.2 using an inflation molding machine. Next, the obtained film was stretched with a feeding speed of 1.0 m / min, a preheating temperature of 100°C, a stretching temperature of 100°C, a cooling temperature of 30°C, and a stretching ratio of 4 times using the longitudinal stretching device of a high-temperature type sequential biaxial stretching device manufactured by Ichikin Kogyo Co., Ltd. to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Comparative Example 2] Manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec LL, linear low-density polyethylene (Q2), grade name: UF421, MFR = 0.9 g / 10 min, density = 0.926 g / cm 3 was prepared. This linear low-density polyethylene was used to produce a 150-μm film at 190°C with a blow ratio of 2.2 using an inflation molding machine. Next, the obtained film was stretched using a longitudinal stretching device of a high-temperature type sequential biaxial stretching device manufactured by Ichikin Kogyo Co., Ltd. at a draw-off speed of 1.0 m / min, a preheating temperature of 100°C, a stretching temperature of 110°C, a cooling temperature of 30°C, and a draw ratio of 7 times to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1. [Comparative Example 3] Instead of the high-density polyethylene used in Example 1, Nippon Polyethylene Co., Ltd. manufactured, trade name Novatec HD, high-density polyethylene (Q3), grade name: HF335, MFR = 0.6 g / 10 min, density = 0.949 g / cm 3 A film was prepared and stretched in the same manner as in Example 1 except for the above to obtain a stretched base film. Other physical properties of the resin and the results of each item are shown in Table 1.

[0060]

Table 1

[0061] <Evaluation> ·Drawability The maximum draw ratio in Table 1 is the evaluation index for drawability. The maximum draw ratio is the maximum draw ratio at which the film can be obtained without breaking by increasing the draw ratio of the film. The maximum draw ratios of Examples 1 to 5 were 9 times or more because the MT values satisfied the requirements of the present invention, but in Comparative Example 1, the MT did not satisfy the requirements of the present invention, so the film could only be drawn up to 4 times. It can be said that the polyethylene resin composition of the present invention is excellent in drawability.

[0062] ·Rigidity The EM and ET in Table 1 are the evaluation indices for rigidity. Since the EM and ET of Examples 1 to 5 satisfy the requirements of the present invention, high-rigidity films are 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 molecular weight distribution (Mw / Mn) does not satisfy the requirements of the present invention, resulting in low rigidity. Therefore, it can be said that the polyethylene resin composition of the present invention is excellent in rigidity.

Claims

[Claim 1] A polyethylene resin composition for a stretched substrate film used as a substrate for a resin laminate, the polyethylene resin composition for a stretched substrate film being characterized in that it satisfies the following physical properties (a-1) to (a-4). (a-1) Density is 0.935 to 0.970 g / cm ３ is (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-3) The melt tension (MT) at 190°C is 8.0 g or less. (a-4) The molecular weight distribution [ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)] measured by gel permeation chromatography (GPC) is 1.5 to 10.0.

Images