Heat-sealable laminated film

Abstract

To provide a polyethylene-based laminated film suitably used for a packaging bag or the like, which has further improved mechanical strength such as Young's modulus while maintaining excellent properties such as blocking resistance.SOLUTION: There is provided a laminated film having (A) a heat fusion layer, (B) an intermediate layer and (C) a laminate layer, each of which contains a linear low density polyethylene derived from petroleum, wherein the intermediate layer (B) contains a plant-derived biomass polyethylene.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyethylene-based laminated film, and more specifically, to a laminated film that is suitably used as a packaging film, particularly excellent in strength (Young's modulus), and has a reduced environmental load by using a plant-derived resin.

Background Art

[0002] A packaging bag formed by heat-sealing a plastic multilayer film is widely used for storing various contents such as food, beverages, detergents, shampoos, and cosmetics. As a film constituting the inner layer side that becomes the heat-sealing part of such a plastic multilayer film, a three-layer structure polyethylene-based laminated film composed of a laminate layer in which a heat-sealing layer, an intermediate layer, and a base film (base material layer) are laminated from the inner layer side has been variously proposed (see, for example, Patent Document 1). These laminated films were designed to have suitable characteristics from the viewpoints of seal strength, impact resistance, blocking resistance, etc., but when used for standing pouches etc., a laminated film having higher mechanical strength has been strongly demanded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In view of the above technical background, an object of the present invention is to provide a polyethylene-based laminated film suitably used for packaging bags etc., which has further improved mechanical strength such as Young's modulus while maintaining excellent properties such as blocking resistance.

Means for Solving the Problems

[0005] As a result of intensive studies, the inventors of the present invention have found that in a laminated film having a heat-sealing layer, an intermediate layer, and a laminate layer each containing petroleum-derived linear low-density polyethylene, the Young's modulus is significantly improved by adding biomass-derived low-density polyethylene to the intermediate layer, and thus the present invention has been completed. That is, the present invention relates to [1] A laminated film having (A) a heat-sealing layer, (B) an intermediate layer, and (C) a laminate layer each containing petroleum-derived linear low-density polyethylene, wherein the (B) intermediate layer contains plant-derived biomass polyethylene. Regarding

[0006] Hereinafter, [2] to [7] are all preferred embodiments or implementations of the present invention. [2] The laminated film according to [1], wherein the heat of fusion ΔH at 0°C to 130°C calculated from the melting curve obtained by DSC measurement is 135 to 164 J / g. [3] The laminated film according to [1] or [2], wherein the molecular weight distribution Mw / Mn of the plant-derived biomass polyethylene is 3.5 or more. [4] The laminated film according to any one of [1] to [3], wherein (A) the heat-sealing layer, (B) the intermediate layer, and (C) the laminate layer all contain plant-derived biomass polyethylene. [5] The laminated film according to any one of [1] to [4], having (D) a base material layer on the side of the (C) laminate layer, either directly or via an adhesive layer. [6] A packaging bag comprising the laminated film according to any one of [1] to [5]. [7] A standing pouch comprising the laminated film according to any one of [1] to [5]. [Advantages of the Invention]

[0007] While maintaining the excellent properties of conventional polyethylene-based laminated films such as blocking resistance, the laminated film of the present invention has a significantly improved Young's modulus and also has properties with high practical value such as reduced environmental impact in its production, etc., and combines these properties at a high level beyond the limits of the prior art. It can be suitably used in various applications including packaging bags such as standing pouches.

Embodiments for Carrying Out the Invention

[0008] The present invention is a laminated film having (A) a heat-sealing layer, (B) an intermediate layer, and (C) a laminate layer each containing linear low-density polyethylene derived from petroleum, wherein the (B) intermediate layer contains biomass polyethylene derived from plants. That is, the laminated film of the present invention contains linear low-density polyethylene derived from petroleum in each of (A) the heat-sealing layer, (B) the intermediate layer, and (C) the laminate layer. In addition, the laminated film of the present invention contains a predetermined amount of biomass polyethylene derived from plants, at least in the (B) intermediate layer.

[0009] Petroleum-derived linear low-density polyethylene The linear low-density polyethylene derived from petroleum used in the present invention is a homopolymer of ethylene produced using petroleum as a raw material, or a copolymer of ethylene produced using petroleum as a raw material and an α-olefin, and may be synthesized by a known production method.

[0010] As the α-olefin, a compound having 3 to 20 carbon atoms can be used. For example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, etc. can be mentioned, and a mixture of these may also be used. The α-olefin is preferably a compound having 4, 6 or 8 carbon atoms or a mixture thereof, and is 1-butene, 1-hexene, 1-octene or a mixture thereof.

[0011] The linear low-density polyethylene derived from petroleum may be a commercially available product. For example, 2040F (C6-LLDPE, MFR: 4.0, density: 0.918 g / cm 3 ) manufactured by Ube-Marubeni Polyethylene Co., Ltd. can be used.

[0012] The linear low-density polyethylene derived from petroleum preferably has a density of 0.905 to 0.935 g / cm 3 , more preferably 0.915 to 0.930 g / cm 3 , and preferably has an MFR of 0.5 to 6.0 g / 10 min, more preferably 2.0 to 4.0 g / 10 min.

[0013] The linear low-density polyethylene derived from petroleum preferably has a molecular weight distribution (expressed as the ratio of weight-average molecular weight: Mw, to number-average molecular weight: Mn, Mw / Mn) of 1.5 to 4.0, more preferably in the range of 1.8 to 3.5. This Mw / Mn can be measured by gel permeation chromatography (GPC).

[0014] The linear low-density polyethylene derived from petroleum has one or more sharp peaks determined from the endothermic curve measured at a heating rate of 10 °C / min with a differential scanning calorimeter (DSC), and the highest temperature of the peak, i.e., the melting point, is preferably 95 to 140 °C, more preferably in the range of 105 to 130 °C.

[0015] The linear low-density polyethylene derived from petroleum can be produced by a conventionally known production method using a conventionally known catalyst such as a multi-site catalyst like a Ziegler catalyst or a single-site catalyst like a metallocene catalyst. From the viewpoint of obtaining a linear low-density polyethylene with a narrow molecular weight distribution and capable of forming a high-strength film, it is preferable to use a single-site catalyst.

[0016] The above-mentioned single-site catalyst is a catalyst capable of forming a uniform active species, and is usually adjusted by bringing a metallocene-based transition metal compound or a non-metallocene-based transition metal compound into contact with an activating cocatalyst. The single-site catalyst is preferred because, compared with a multi-site catalyst, the active site structure is uniform, so that a polymer having a high molecular weight and a high degree of uniformity can be polymerized. As the single-site catalyst, it is particularly preferable to use a metallocene-based catalyst. The metallocene-based catalyst is a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a cocatalyst, an organometallic compound if necessary, and each catalyst component of a carrier.

[0017] In the transition metal compound of Group IV of the periodic table containing a ligand having the above-mentioned cyclopentadienyl skeleton, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, etc. Examples of the substituted cyclopentadienyl group include those having at least one substituent selected from hydrocarbon groups having 1 to 30 carbon atoms, silyl groups, silyl-substituted alkyl groups, silyl-substituted aryl groups, cyano groups, cyanoalkyl groups, cyanoaryl groups, halogen groups, haloalkyl groups, halosilyl groups, etc. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may be bonded to each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulene ring, or a hydrogenated product thereof. The rings formed by bonding the substituents to each other may further have substituents.

[0018] In a Group IV transition metal compound of the periodic table containing a ligand having a cyclopentadienyl skeleton, examples of the transition metal include zirconium, titanium, hafnium, etc., and zirconium and hafnium are particularly preferred. The transition metal compound usually has two ligands having a cyclopentadienyl skeleton, and it is preferred that the ligands having a cyclopentadienyl skeleton are bonded to each other by a bridging group. Examples of the bridging group include an alkylene group having 1 to 4 carbon atoms, a silylene group, a dialkylsilylene group, a substituted silylene group such as a diarylsilylene group, a dialkylgermylene group, a substituted germylene group such as a diarylgermylene group, etc. Preferably, it is a substituted silylene group.

[0019] In a Group IV transition metal compound of the periodic table, typical ligands other than the ligand having a cyclopentadienyl skeleton include hydrogen, a hydrocarbon group having 1 to 20 carbon atoms (alkyl group, alkenyl group, aryl group, alkylaryl group, aralkyl group, polyenyl group, etc.), halogen, a metaalkyl group, a metaaryl group, etc.

[0020] The Group IV transition metal compound of the periodic table containing the ligand having a cyclopentadienyl skeleton as described above can be a catalyst component in the form of one kind or a mixture of two or more kinds.

[0021] The cocatalyst refers to one that can effectively deactivate the above Group IV transition metal compound of the periodic table as a polymerization catalyst or can balance the ionic charges in a catalytically activated state. Examples of the cocatalyst include a benzene-soluble aluminoxane or a benzene-insoluble organoaluminum oxy compound of an organoaluminum oxy compound, an ion-exchangeable layered silicate, a boron compound, an ionic compound composed of a cation containing or not containing an active hydrogen group and a non-coordinating anion, a lanthanoid salt such as lanthanum oxide, tin oxide, a phenoxy compound containing a fluoro group, etc.

[0022] Transition metal compounds of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton may be used by being supported on a carrier of an inorganic or organic compound. As the carrier, a porous oxide of an inorganic or organic compound is preferable. Specifically, ion-exchangeable layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, etc. or mixtures thereof may be mentioned.

[0023] Furthermore, examples of the organometallic compounds that may be used as necessary include organoaluminum compounds, organomagnesium compounds, organozinc compounds, etc. Among these, organoaluminum is preferably used.

[0024] The linear low-density polyethylene derived from petroleum may be used alone or in combination of two or more. Also, it may be used together with other polymers including other ethylene-based polymers.

[0025] The linear low-density polyethylene derived from petroleum can be blended as necessary with various known additives usually added to olefin polymers, such as antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, slip agents (lubricants), etc., within a range not impairing the object of the present invention.

[0026] Plant-derived biomass polyethylene The biomass polyethylene derived from plants used in the present invention is polyethylene obtained by polymerizing ethylene produced using plants as a raw material. In the present invention, the biomass polyethylene derived from plants may be any of high-density polyethylene, low-density polyethylene, and linear low-density polyethylene, but is preferably low-density polyethylene or linear low-density polyethylene, and particularly preferably low-density polyethylene.

[0027] Plant-derived polyethylene may be a commercially available product. For example, those manufactured and sold by Braskem can be used. Specifically, SLH218 and SPB681 can be preferably used. The plant-derived biomass polyethylene used in the present invention is formed by polymerizing a monomer containing ethylene derived from biomass. It is preferable to use, but not limited to, ethylene derived from biomass obtained by the following production methods. Since ethylene derived from biomass is used as the monomer as the raw material, the resulting polyethylene is derived from biomass. Note that the raw material monomer of polyethylene does not have to contain 100% by mass of ethylene derived from biomass, and may contain ethylene not derived from biomass or raw material monomers other than ethylene.

[0028] The production method of biomass ethylene used as the raw material of plant-derived biomass polyethylene is not particularly limited, and can be obtained by a conventionally known method. Hereinafter, an example of the production method of biomass ethylene will be described.

[0029] Biomass ethylene can be produced using ethanol derived from biomass as a raw material. In particular, it is preferable to use fermented ethanol derived from biomass obtained from plant raw materials. The plant raw materials are not particularly limited, and conventionally known plants can be used. For example, corn, sugarcane, beet, and cassava can be mentioned.

[0030] In the present invention, fermented ethanol derived from biomass refers to ethanol produced by contacting a culture solution containing a carbon source obtained from plant raw materials with a microorganism that produces ethanol or a product derived from the disruption of the microorganism, and then purified ethanol. Conventional known methods such as distillation, membrane separation, and extraction can be applied to purify ethanol from the culture solution. For example, methods such as adding benzene, cyclohexane, etc. and azeotroping, or removing water by membrane separation, etc. can be mentioned. To obtain biomass ethylene, at this stage, further advanced purification such as reducing the total amount of impurities in ethanol to 1 ppm or less may be carried out.

[0031] When ethylene is obtained by the dehydration reaction of ethanol, a catalyst is usually used. This catalyst is not particularly limited, and a conventionally known catalyst can be used. Advantageous in the process is a fixed-bed flow reaction in which the separation of the catalyst and the product is easy. For example, γ-alumina or the like is preferable. Since this dehydration reaction is an endothermic reaction, it is usually carried out under heating conditions. At a commercially useful reaction rate As the reaction proceeds, the heating temperature is not limited, but preferably 100 °C or higher, more preferably 250 °C or higher, and even more preferably 300 °C or higher. The upper limit is also not particularly limited, but from the viewpoints of energy balance and equipment, it is preferably 500 °C or lower, more preferably 400 °C or lower. The reaction pressure is not particularly limited, but a pressure equal to or higher than atmospheric pressure is preferable in order to facilitate subsequent gas-liquid separation. Industrially, a fixed-bed flow reaction in which the separation of the catalyst is easy is suitable, but a liquid-phase suspension bed, a fluidized bed, etc. may also be used.

[0032] In the dehydration reaction of ethanol, the reaction yield depends on the water content contained in the ethanol supplied as a raw material. Generally, when carrying out the dehydration reaction, it is preferable that there is no water in consideration of the water removal efficiency. However, in the case of the dehydration reaction of ethanol using a solid catalyst, it has been found that the production amount of other olefins, particularly butene, tends to increase when there is no water. Presumably, it is because the dimerization of ethylene after dehydration cannot be suppressed without the presence of a small amount of water. The lower limit of the allowable water content needs to be 0.1 mass% or more, preferably 0.5 mass% or more. The upper limit is not particularly limited, but from the viewpoints of material balance and heat balance, it is preferably 50 mass% or lower, more preferably 30 mass% or lower, and even more preferably 20 mass% or lower.

[0033] By performing the dehydration reaction of ethanol in this way, a mixture of ethylene, water, and a small amount of unreacted ethanol can be obtained. Since ethylene is a gas at normal temperature and below about 5 MPa, water and ethanol can be removed from this mixture by gas-liquid separation to obtain ethylene. This method may be carried out by a known method. The ethylene obtained by gas-liquid separation is further distilled. The distillation method, operating temperature, residence time, etc. are not particularly restricted, except that the operating pressure at this time is equal to or higher than atmospheric pressure.

[0034] When the raw material is fermentation ethanol derived from biomass, the obtained ethylene contains extremely small amounts of carbonyl compounds such as ketones, aldehydes, and esters, which are impurities mixed in the ethanol fermentation process, as well as carbon dioxide gas, which is a decomposition product thereof, and nitrogen-containing compounds such as amines and amino acids, which are decomposition products and contaminants of enzymes, and ammonia, which is a decomposition product thereof. In the production and use of polyethylene, these extremely small amounts of impurities may cause problems, so they may be removed by purification. The purification method is not particularly limited and can be carried out by a conventionally known method. As a suitable purification operation, for example, an adsorption purification method can be mentioned. The adsorbent used is not particularly limited, and a conventionally known adsorbent can be used. For example, a material with a high surface area is preferred, and the type of adsorbent is selected according to the type and amount of impurities in the ethylene obtained by the dehydration reaction of fermentation ethanol derived from biomass.

[0035] Note that caustic water treatment may be used in combination as a method for purifying impurities in ethylene. When performing caustic water treatment, it is desirable to carry it out before adsorption purification. In that case, it is necessary to perform a moisture removal treatment after the caustic treatment and before the adsorption purification.

[0036] The monomer, which is a raw material for plant-derived biomass polyethylene, may further contain ethylene and / or α-olefin derived from fossil fuels, or may further contain α-olefin derived from biomass.

[0037] The above α-olefin is not particularly limited in terms of the number of carbon atoms, but usually those having 3 to 20 carbon atoms can be used, and it is preferably butylene, hexene, or octene. This is because if it is butylene, hexene, or octene, it can be produced by the polymerization of ethylene which is a raw material derived from biomass. Further, by including such an α-olefin, the resulting polyolefin has an alkyl group as a branched structure, so that it can be made more flexible than a simple linear one.

[0038] It is preferable that the above polyethylene is a homopolymer of ethylene. This is because by using ethylene which is a raw material derived from biomass, it is theoretically possible to produce it with components derived from biomass at 100%.

[0039] The concentration of ethylene derived from biomass in the above polyethylene (hereinafter sometimes referred to as "biomass degree") is a value obtained by measuring the content of carbon derived from biomass by radioactive carbon ( 14 C) measurement. Since carbon dioxide in the atmosphere contains 14 C at a certain ratio (105.5 pMC), it is known that the 14 C content in plants that take in carbon dioxide in the atmosphere and grow, such as corn, is also about 105.5 pMC. It is also known that fossil fuels contain almost no 14 C. Therefore, by measuring the ratio of 14 C contained in all carbon atoms in polyethylene, the ratio of carbon derived from biomass can be calculated. In the present invention, when the content of 14 C in polyethylene is P 14C , the content P bio of carbon derived from biomass can be obtained as follows. P bio (%) = P 14C / 105.5 × 100

[0040] In the case of biomass polyethylene used in the present invention, theoretically, if all ethylene derived from biomass is used as a raw material for polyethylene, the concentration of ethylene derived from biomass is 100%, and the biomass content of polyethylene derived from biomass is 100%. Further, the concentration of ethylene derived from biomass in polyethylene derived from fossil fuels produced only from raw materials derived from fossil fuels is 0%, and the biomass content of polyethylene derived from fossil fuels is 0%.

[0041] In the present invention, biomass polyethylene does not necessarily have a biomass content of 100%. This is because even if a raw material derived from biomass is used in part of the biomass polyethylene, the amount of fossil fuel used can be reduced compared to the conventional case.

[0042] In the biomass polyethylene used in the present invention, the polymerization method of the monomer containing ethylene derived from biomass is not particularly limited, and it can be carried out by a conventionally known method. The polymerization temperature and polymerization pressure may be appropriately adjusted according to the polymerization method and polymerization apparatus. The polymerization apparatus is also not particularly limited, and a conventionally known apparatus can be used. For example, the polymerization method of the monomer containing ethylene described below can be applied.

[0043] The polymerization method of biomass polyethylene can be appropriately selected according to the type of polyethylene targeted, for example, the differences in density and branching such as high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). For example, as a polymerization catalyst, a multi-site catalyst such as a Ziegler catalyst or a Phillips catalyst, or a single-site catalyst such as a metallocene-based catalyst is used, and it is preferably carried out in one stage or in multiple stages of two or more stages by any of gas-phase polymerization, slurry polymerization, solution polymerization, and high-pressure ionic polymerization.

[0044] From the viewpoint of obtaining biomass polyethylene having a wide molecular weight distribution and excellent flexibility and moldability, it is preferable to use a multi-site catalyst such as a Ziegler catalyst or a Phillips catalyst. Preferred Ziegler catalysts may be those generally known as Ziegler catalysts for the coordination polymerization of ethylene and α-olefins. For example, they may be catalysts containing a titanium compound and an organoaluminum compound, such as catalysts composed of a titanium halide compound and an organoaluminum compound, or catalysts composed of a solid catalyst component consisting of titanium, magnesium, chlorine, etc. and an organoaluminum compound. More specifically, examples of such catalysts include catalysts composed of catalyst component (a) obtained by reacting a titanium compound with the reaction product of an alcohol pretreatment product of anhydrous magnesium dihalide and an organometallic compound and an organometallic compound (b), catalysts composed of catalyst component (A) obtained by reacting magnesium metal with an organic hydroxide compound or an oxygen-containing organic compound such as magnesium, an oxygen-containing organic compound of a transition metal, and an aluminum halide and a catalyst component (B) of an organometallic compound, and catalysts composed of solid catalyst component (A) obtained by reacting (i) at least one member selected from metallic magnesium, an organic hydroxide compound, an oxygen-containing organic compound of magnesium, and a halogen-containing compound, (ii) at least one member selected from an oxygen-containing organic compound and a halogen-containing compound of a transition metal, (iii) a reaction product obtained by reacting a silicon compound, and (iv) an aluminum halide compound and a catalyst component (B) of an organometallic compound.

[0045] Also, Phillips catalysts may be those generally known as Phillips catalysts for the coordination polymerization of ethylene and α-olefins. For example, they may be catalyst systems containing a chromium compound such as chromium oxide. Specifically, examples include catalysts in which a chromium compound such as chromium trioxide or a chromium acid ester is supported on a solid oxide such as silica, alumina, silica-alumina, or silica-titania.

[0046] There is no particular limitation on the density of plant-derived biomass polyethylene, but preferably it is 0.905 to 0.935 g / cm 3 , more preferably 0.915 to 0.930 g / cm 3That is, the plant-derived biomass polyethylene is preferably low-density polyethylene or linear low-density polyethylene. There is no particular limitation on the MFR of the plant-derived biomass polyethylene, but from the viewpoint of moldability and the like, it is preferably 0.3 to 15.0 g / 10 min, more preferably 1.0 to 12.0 g / 10 min, still more preferably 1.5 to 10.0 g / 10 min, and particularly preferably 2.0 to 9.0 g / 10 min.

[0047] There is no particular limitation on the molecular weight distribution of the plant-derived biomass polyethylene, but from the viewpoints of flexibility, moldability, etc., the molecular weight distribution (expressed as the ratio of weight-average molecular weight: Mw, to number-average molecular weight: Mn, Mw / Mn) is preferably 3.5 or more, more preferably 3.8 to 9.0, and still more preferably 4.0 to 8.6. This Mw / Mn can be measured by gel permeation chromatography (GPC), and more specifically, for example, it can be measured by the method described in the examples of the present application.

[0048] In addition, the plant-derived biomass polyethylene has one or more sharp peaks obtained from the endothermic curve measured at a heating rate of 10 °C / min by a differential scanning calorimeter (DSC), and the highest temperature of the peak, that is, the melting point is preferably 95 to 140 °C, and more preferably in the range of 100 to 135 °C.

[0049] The plant-derived biomass polyethylene may be used alone or in combination of two or more. It may also be used together with other polymers, including other ethylene-based polymers.

[0050] The plant-derived biomass polyethylene can be blended with various known additives usually added to olefin polymers, such as antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, slip agents (lubricants), etc., as necessary, within a range that does not impair the object of the present invention.

[0051] The laminated film of the present invention has the following (A) heat-sealing layer, (B) intermediate layer, and (C) laminate layer. (A) The heat-sealing layer, (B) the intermediate layer, and (C) the laminate layer all contain the above-mentioned petroleum-derived linear low-density polyethylene. By (A) the heat-sealing layer, (B) the intermediate layer, and (C) the laminate layer all containing the above-mentioned petroleum-derived linear low-density polyethylene, the lamination strength between the layers can be made sufficient. Also, it is advantageous in terms of the productivity and cost of the laminated film.

[0052] (A) Heat-sealing layer The (A) heat-sealing layer constituting the laminated film of the present invention is often used as the innermost layer and fused with other films when forming a packaging bag using the laminated film of the present invention. For this reason, it is preferable to use a resin with a low melting point so as to obtain high seal strength. For example, by setting the ethylene content of the petroleum-derived linear low-density polyethylene low, the melting point of the (A) heat-sealing layer can be lowered. More specifically, it is preferable that the ethylene content of the petroleum-derived linear low-density polyethylene is 10% by mass or less, more preferably 7% by mass or less, and still more preferably 5% by mass or less.

[0053] When it is necessary to increase the ethylene content of the petroleum-derived linear low-density polyethylene due to the strength of the film and the need to use the same material as other layers, a resin with a low melting point may be added to the (A) heat-sealing layer. Also, when adding plant-derived biomass polyethylene to the (A) heat-sealing layer, plant-derived biomass polyethylene with a low melting point may be added. Examples of the above-mentioned other low-melting-point resins include relatively low-density ethylene-based polymers such as high-pressure method low-density polyethylene and ethylene·α-olefin random copolymers; tackifying resins such as aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins, polyterpene resins, rosins, styrene resins, and coumarone-indene resins, and the like.

[0054] From the viewpoint of heat sealability and the like, the content of petroleum-derived linear low-density polyethylene in the (A) heat-sealing layer is preferably 50% by mass or more, more preferably 55 to 99% by mass, and particularly preferably 65 to 95% by mass. From the viewpoint of rigidity and the like, the content of plant-derived biomass polyethylene in the (A) heat-sealing layer is preferably 1% by mass or more, more preferably 5 to 40% by mass, and particularly preferably 7 to 30% by mass.

[0055] (A) The thickness of the heat-sealing layer is not particularly limited, but from the viewpoint of heat sealability and the like, it is preferably 5 μm or more, and more preferably 10 μm or more. On the other hand, from the viewpoint of film strength and the like, it is preferably 30 μm or less, and more preferably 20 μm or less.

[0056] In the heat-sealing layer, various known additives usually added to polyolefins, such as antiblocking agents, slip agents (lubricants), antioxidants, weather stabilizers, antistatic agents, antifogging agents, etc., can be blended as necessary within a range not impairing the object of the present invention. Examples of the antiblocking agent include silica, talc, silica, clay, calcium carbonate, synthetic zeolite, starch, aluminum oxide, acrylic resin, methacrylic resin, silicone resin, polytetrafluoroethylene resin, etc. Examples of the slip agent include various amides such as palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, oleyl palmitamide, stearyl palmitamide, methylene bis stearyl amide, methylene bis oleyl amide, ethylene bis oleyl amide, ethylene bis erucic acid amide, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and hydrogenated castor oil.

[0057] (B) Intermediate layer Among the respective layers constituting the laminated film of the present invention, it is preferable to design the (A) heat-sealing layer so as to obtain an appropriate seal strength. In contrast, for the (C) laminate layer, it is preferable to design it in consideration of the laminate strength and the like with the (D) base material layer and the like. On the other hand, since there are relatively few such restrictions for the (B) intermediate layer, it is possible to preferentially design it to impart desired physical properties and performance to the entire laminated film of the present invention, such as mechanical properties. In this case, it is preferable that the thickness of the (B) intermediate layer is larger than the thickness of the (A) heat-sealing layer and the thickness of the (C) laminate layer, and it is particularly preferable that the thickness of the (B) intermediate layer is larger than the sum of the thickness of the (A) heat-sealing layer and the thickness of the (C) laminate layer. More specifically, the thickness of the (B) intermediate layer is preferably 10 μm or more, more preferably 15 μm or more, and particularly preferably 30 μm or more. On the other hand, from the viewpoint of heat-sealability and the like, the thickness of the (B) intermediate layer is preferably 150 μm or less, more preferably 130 μm or less, still more preferably 100 μm or less, and particularly preferably 90 μm or less.

[0058] For example, from the viewpoint of realizing high mechanical strength for the entire laminate, it is preferable to use a resin having high mechanical strength at a high ratio in the (B) intermediate layer. For example, as the linear low-density polyethylene derived from petroleum, it is preferable to select one having a high molecular weight and a narrow molecular weight distribution, and further to set its content high. From this viewpoint, the content of the linear low-density polyethylene derived from petroleum in the (A) heat-sealing layer is preferably 50% by mass or more, more preferably 75 to 100% by mass, still more preferably 85 to 100% by mass, and particularly preferably 90 to 100% by mass. Also, the molecular weight distribution of the linear low-density polyethylene derived from petroleum is preferably 4.0 or less, and particularly preferably 3.0 or less. Similarly, the molecular weight of the linear low-density polyethylene derived from petroleum is preferably 20,000 or more, more preferably 25,000 or more, still more preferably 50,000 or more, and particularly preferably 70,000 or more.

[0059] From the viewpoint of improving the flexibility and impact resistance of the entire laminate, it is preferable to use a resin having high flexibility and impact resistance at a high ratio in the (B) intermediate layer. For example, as a linear low-density polyethylene derived from petroleum, a resin having high flexibility and impact resistance can be selected, and its content can be set higher. Also, by adding an elastomer or a rubber component to the (B) intermediate layer, the flexibility and impact resistance of the (B) intermediate layer can be improved, and the flexibility and impact resistance of the entire laminate can be improved. Examples of the elastomer or rubber component at this time include ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-propylene-butene copolymer, etc., and the addition amount can be 1 to 30% by mass, preferably 5 to 10% by mass.

[0060] (C) Laminated layer The (C) laminate layer constituting the laminated film of the present invention can be laminated with other layers including the (D) base material layer described later as necessary or desired. Therefore, it is preferable to design the (C) laminate layer in consideration of the laminate strength and the like between it and other layers. From this viewpoint, it is preferable to appropriately select linear low-density polyethylene derived from petroleum in the (C) laminate layer that has excellent affinity with other layers including the (D) base material layer, and its content is preferably 40 to 99% by mass, particularly preferably 70 to 95% by mass. Also, in order to further improve the laminate strength between it and other layers, a treatment such as corona treatment or roughening treatment may be performed on the surface of the (C) laminate layer (the surface opposite to the surface laminated with the (B) intermediate layer).

[0061] On the other hand, from the viewpoint of preventing blocking when storing the laminated film of the present invention, etc., the (C) laminate layer may contain an anti-blocking agent. As the anti-blocking agent, powdery silica, preferably synthetic silica, etc. can be suitably used. From the viewpoint of uniformly dispersing the powdery silica in the (C) laminate layer, the powdery silica is dispersed in a resin having excellent miscibility with the petroleum-derived linear low-density polyethylene constituting the (C) laminate layer, for example, in low-density polyethylene, to form a masterbatch, and then the masterbatch may be added to the petroleum-derived linear low-density polyethylene. Further, a slip agent (lubricant) can be blended in the laminate layer as needed within a range not impairing the object of the present invention. Examples of the slip agent include various amides such as palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, oleyl palmitamide amide, stearyl palmitamide amide, methylene bis stearyl amide, methylene bis oleyl amide, ethylene bis oleyl amide, ethylene bis erucic acid amide, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and hydrogenated castor oil.

[0062] The thickness of the (C) laminate layer is not particularly limited, but from the viewpoints of laminate processability and the like, it is preferably 5 μm or more, and particularly preferably 10 μm or more. On the other hand, from the viewpoints of film strength and the like, it is preferably 30 μm or less, and particularly preferably 20 μm or less.

[0063] Any of the (A) heat-sealing layer, (B) intermediate layer, and (C) laminate layer may be added with various additives and fillers other than petroleum-derived linear low-density polyethylene (and, if present, plant-derived biomass polyethylene) as long as it does not contravene the object of the present invention, for example, heat stabilizers, antioxidants, light stabilizers, antistatic agents, anti-blocking agents, lubricants, nucleating agents, flame retardants, pigments, dyes, calcium carbonate, barium sulfate, magnesium hydroxide, mica, talc, clay, antibacterial agents, antifogging agents, etc. Furthermore, other thermoplastic resins, thermoplastic elastomers, rubbers, hydrocarbon resins, petroleum resins, etc. may be blended within a range not contravening the object of the present invention.

[0064] Laminated film The laminated film of the present invention has a (A) heat-sealing layer, a (B) intermediate layer, and a (C) laminate layer each containing a linear low-density polyethylene derived from petroleum. In the laminated film of the present invention, preferably, the (C) laminate layer and the (A) heat-sealing layer are laminated via the (B) intermediate layer, but other layers may be present.

[0065] The laminated film of the present invention can adopt various known film forming methods, for example, a method of forming films to be the (C) laminate layer, the (B) intermediate layer, and the (A) heat-sealing layer in advance and then laminating the films to form a laminated film, a method of obtaining a multilayer film composed of the (B) intermediate layer and the (A) heat-sealing layer using a multilayer die and then extruding the (C) laminate layer onto the surface of the (B) intermediate layer to form a laminated film, a method of obtaining a multilayer film composed of the (C) laminate layer and the (B) intermediate layer using a multilayer die and then extruding the (A) heat-sealing layer onto the surface of the (B) intermediate layer to form a laminated film, or a method of obtaining a laminated film composed of the (C) laminate layer, the (B) intermediate layer, and the (A) heat-sealing layer using a multilayer die, etc.

[0066] Also, as the film forming method, various known film forming methods can be adopted, specifically, a T-die casting film forming method and an inflation film forming method can be adopted. The laminated film of the present invention and each layer constituting the same may be an unstretched film (non-stretched film) or a stretched film.

[0067] There is no particular limitation on the thickness of each layer of the laminated film of the present invention, but it is usually in the range of 3 μm or more, preferably 5 to 150 μm, more preferably 5 to 90 μm. Although the thickness of the laminated film of the present invention is not particularly limited, from the viewpoint of ensuring practical strength, etc., it is usually 20 μm or more, preferably 25 μm or more, more preferably 30 μm or more. On the other hand, from the viewpoint of having practical flexibility even after being laminated with, for example, the (D) base material layer, it is usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less.

[0068] The laminated film of the present invention contains biomass polyethylene derived from plants in the (B) intermediate layer. By containing biomass polyethylene derived from plants in the (B) intermediate layer, the laminated film of the present invention realizes a remarkable technical effect that the Young's modulus is significantly improved while maintaining excellent properties of conventional polyethylene-based laminated films such as blocking resistance. Since the Young's modulus of the laminated film of the present invention is significantly improved, it is particularly advantageous for applications such as standing pouches that require high mechanical strength.

[0069] The content of biomass polyethylene derived from plants in the (B) intermediate layer is preferably 3% by mass or more, more preferably 4.4% by mass or more, still more preferably 10% by mass or more, and particularly preferably 15% by mass or more. There is no particular upper limit to the content of biomass polyethylene derived from plants in the (B) intermediate layer, but from the viewpoint of bag breakage resistance, etc., it is preferably usually 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less.

[0070] The laminated film of the present invention only needs to contain biomass polyethylene derived from plants in the (B) intermediate layer, but from the viewpoint of further improving the Young's modulus and further reducing the environmental load, it is also preferable to contain biomass polyethylene derived from plants in the (A) heat-sealing layer and / or the (C) laminate layer. It is particularly preferable to contain biomass polyethylene derived from plants in all of the (A) heat-sealing layer, the (B) intermediate layer, and the (C) laminate layer. The content of plant-derived biomass polyethylene in the (A) heat-sealing layer and / or the (C) laminate layer is preferably 10% by mass or more, and particularly preferably 20% by mass or more. There is no particular upper limit for the content of plant-derived biomass polyethylene in the (A) heat-sealing layer and / or the (C) laminate layer. However, from the viewpoints of bag bursting resistance and the like, it is usually 50% by mass or less, preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0071] The content of plant-derived biomass polyethylene in the laminated film of the present invention is preferably 6% by mass or more, and particularly preferably 12% by mass or more. There is no particular upper limit for the content of plant-derived biomass polyethylene in the laminated film of the present invention. However, from the viewpoints of tearability and film strength, etc., it is preferably usually 30% by mass or less. The content of plant-derived biomass polyethylene can be appropriately increased or decreased, for example, by adjusting the formulation of the resin composition when manufacturing each layer. The content of plant-derived biomass polyethylene in each layer of the film after production can be calculated, for example, by measuring the content of biomass-derived carbon in the film by measuring radioactive carbon ( 14 C) and from this measurement result and the content of biomass-derived carbon in the plant-derived biomass polyethylene.

[0072] By containing plant-derived biomass polyethylene in the (B) intermediate layer (and preferably also in the (A) heat-sealing layer and / or the (C) laminate layer), the laminated film of the present invention can reduce the amount of fossil fuel used in production and reduce the environmental load. The biomass degree of the laminated film can be calculated by weighted-averaging the biomass degrees of each layer by the weight of each layer. The biomass degree of the laminated film can be appropriately increased or decreased by adjusting the biomass degrees of each layer, and the biomass degree of each layer can be appropriately increased or decreased by adjusting the biomass degree and the amount of use of the resin used in each layer. The biomass content of the laminated film of the present invention is more preferably 5% by mass or more, and particularly preferably 10% by mass or more. The higher the biomass content of the laminated film of the present invention, the more preferable it is. Although there is no particular upper limit, from the viewpoint of the physical properties of the film, cost, etc., it is usually 60% by mass or less, and in many cases 30% by mass or less.

[0073] The heat of fusion ΔH from 0 °C to 130 °C calculated from the melting curve obtained by DSC measurement of the laminated film of the present invention is preferably 135 to 164 J / g. When the heat of fusion ΔH from 0 °C to 130 °C is within the above range, the Young's modulus of the laminated film can be more effectively improved. The measurement of the melting curve by DSC and the calculation of the heat of fusion ΔH from 0 °C to 130 °C from the melting curve can be carried out by a conventionally known method, and more specifically, for example, by the method described in the examples of the present application. The heat of fusion ΔH from 0 °C to 130 °C is more preferably 135 to 164 J / g, and particularly preferably 140 to 164 J / g. The heat of fusion ΔH from 0 °C to 130 °C can be decreased by reducing the crystallinity of the film, for example, by adding components other than petroleum-derived linear low-density polyethylene. As components other than petroleum-derived linear low-density polyethylene, it is preferable to add plant-derived biomass polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-propylene-butene copolymer, etc.

[0074] The laminated film of the present invention may be a stretched film or an unstretched film. From the viewpoint of improving mechanical properties, it is preferably a stretched film, and particularly preferably a biaxially stretched film. For biaxial stretching, methods such as sequential biaxial stretching, simultaneous biaxial stretching, and multi-stage stretching are appropriately adopted. As the conditions for biaxial stretching, the manufacturing conditions of known biaxially stretched films can be cited. For example, in the sequential biaxial stretching method, the longitudinal stretching temperature is in the range of 100°C to 145°C, the stretching ratio is in the range of 4 to 7 times, the transverse stretching temperature is 150 to 190°C, and the stretching ratio is in the range of 8 to 11 times.

[0075] (D) Substrate layer If desired, the laminated film of the present invention can be laminated with the (D) base material layer in its (C) laminate layer. There are no particular restrictions on the (D) base material layer, and for example, films usually used for plastic packaging bags can be preferably used. Preferred materials for the (D) base material layer include, for example, polyolefins such as crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly-4-methylpentene-1, low-, medium-, or high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ion-crosslinked olefin copolymer (ionomer); aromatic vinyl copolymers such as polystyrene, styrene-butadiene copolymer; vinyl halide polymers such as polyvinyl chloride, vinylidene chloride resin; nitrile polymers such as acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer; polyamides such as nylon 6, nylon 66, para or metaxylylene adipamide; polyesters such as polyethylene terephthalate (PET), polytetramethylene terephthalate; various polycarbonates; plastic films composed of thermoplastic resins such as polyacetals such as polyoxymethylene. Also, when the content to be packaged is sensitive to oxygen, a film obtained by vapor-depositing a metal oxide or the like on the above film, or a film coated with an organic compound, or a layer made of ethylene-vinyl alcohol copolymer (EVOH) resin may be provided. Plastic films made of these materials are used in an unstretched, uniaxially stretched, or biaxially stretched state.

[0076] (D) As the base material layer, these plastic films can be used singly or in the form of a laminate of two or more kinds. Further, it is also possible to form a structure by laminating one kind or two or more kinds of these plastic films with a metal foil such as aluminum, paper, cellophane, etc. Preferred (D) base material layers include, for example, single-layer films made of stretched nylon film and stretched polyester film, two-layer films formed by laminating a polyolefin film such as low-density polyethylene and polypropylene with PET, three-layer films formed by laminating PET / nylon / polyethylene, etc. When manufacturing these laminated films, an adhesive or an anchor agent can be interposed between each layer as necessary. Also, an ink layer for expressing a design may be provided.

[0077] (D) There is no particular limitation on the method of laminating the base material layer to the (C) laminate layer. For example, the (D) base material layer can be directly laminated to the (C) laminate layer by extrusion lamination or the like. Also, the (D) base material layer may be laminated to the (C) laminate layer via an adhesive by dry lamination or the like. As the adhesive, ordinary ones such as urethane-based adhesives, acid-modified polyolefin-based adhesives, polyester-based adhesives, polyether-based adhesives, polyamide-based adhesives, etc. can be used. (D) The thickness of the base material layer can be arbitrarily set, but usually, it is selected from the range of 5 to 50 μm, preferably 10 to 30 μm.

[0078] The laminated film of the present invention and the laminated film obtained by laminating the (D) base material layer to the (C) laminate layer of the laminated film of the present invention are preferably used in various applications, and are particularly suitable for use as a packaging material. When used as a packaging material, in the (A) heat-sealing layer, the laminated films or the laminated film and another film can be heat-sealed to form a packaging bag. Since the laminated film of the present invention has an improved Young's modulus, such a packaging bag is easy to stand on its own and can be preferably used, for example, as a standing pouch. There are no particular restrictions on the contents to be stored in the packaging bag using the laminated film of the present invention, preferably a standing pouch. For example, it is particularly suitable for storing liquids such as liquid medicines, toiletry products such as liquid detergents and fabric softeners, or liquid foods such as concentrated coffee, as well as powders such as powder detergents, sugar, pepper, and salt.

Examples

[0079] Hereinafter, the present invention will be specifically described with reference to Examples / Comparative Examples. It should be noted that the present invention is not limited by the following examples in any sense.

[0080] The physical properties and characteristics in the Examples / Comparative Examples were evaluated by the following methods. (1) Molecular weight distribution (Mw / Mn) Under the following conditions, after pre-treating the polymer sample, the molecular weight was measured by GPC, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) was taken as the molecular weight distribution. i) Pretreatment To 30 mg of the sample, 20 mL of the mobile phase for GPC measurement (o-dichlorobenzene) was added, and the mixture was shaken and dissolved at 145°C. The resulting solution was heat-filtered through a sintered filter with a pore size of 1.0 μm and used for GPC measurement. ii) GPC Apparatus: Gel permeation chromatograph HLC-8321 manufactured by Tosoh Corporation Column: Four columns with an inner diameter of 7.5 mm × 30 cm manufactured by Tosoh Corporation (TSKgel GMH6-HT: 2 columns, and TSKgel GMH6-HTL: 2 columns) ) Column temperature: 140°C Detector: Differential refractometer Flow rate: 1 mL / min Sampling interval: 0.5 seconds (2) Heat of fusion Using a Q100 manufactured by TA Instruments as a differential scanning calorimeter (DSC), approximately 5 mg of the sample was precisely weighed, and in accordance with JIS K7121, under the conditions of a nitrogen gas flow rate of 50 ml / min, the temperature was raised from 25°C to 200°C at a heating rate of 10°C / min to measure the heat melting curve, and the crystal melting heat of the sample was determined from the obtained heat melting curve.

[0081] (3) Young's modulus As test specimens, strip-shaped film pieces (length: 150 mm, width: 15 mm) were cut out from the film in the longitudinal direction (MD) and the transverse direction (TD), and using a tensile testing machine (manufactured by A&D Company, Ltd., RTG1210), a tensile test was conducted under the conditions of a chuck distance of 100 mm and a crosshead speed of 5 mm / min to obtain the Young's modulus (MPa). The measured values are the average of 5 measurements.

[0082] (Comparative Example 1) The components constituting each layer were in the formulations shown in Table 1, and were respectively supplied to separate extruders, and a laminated film having an (A) heat-sealing layer, a (B) intermediate layer, and a (C) laminate layer of the resin composition shown in Table 1 with the layer structure also shown in Table 1 was produced by the T-die method. Since plant-derived biomass polyethylene was not used, the biomass content was 0 mass%. For the produced film, evaluation of the heat of fusion and Young's modulus was performed. The results are shown in Table 1.

[0083] (Comparative Examples 2 to 5, and Examples 1 to 8) Except for changing the resin composition as shown in Table 1, such as using plant-derived biomass polyethylene, a laminated film was produced in the same manner as Comparative Example 1, and evaluation of the heat of fusion and Young's modulus was performed. The results are shown in Table 1.

[0084] The details of each constituent component described by abbreviations in the resin composition column in Table 1 are as follows. ·LLDPE Petroleum-derived linear low-density polyethylene MFR (2.16 kg, 190°C): 2.3 g / 10 min Density: 918 kg / m 3 Molecular weight distribution (Mw / Mn): 2.52 · Bio-PE Plant-derived biomass low-density polyethylene MFR (2.16 kg, 190 °C): 3.8 g / 10 min Density: 922 kg / m 3 Molecular weight distribution (Mw / Mn): 5.88

[0085]

Table 1

Industrial Applicability

[0086] While maintaining the excellent properties of conventional polyethylene-based laminated films, the laminated film of the present invention significantly improves mechanical properties such as Young's modulus, which are particularly important when used in packaging bags such as standing pouches, and also reduces the environmental load in its production, etc. It has high practical value and combines high-level properties, is particularly suitable for use in packaging bags such as standing pouches, and has high applicability in various fields of industries such as agriculture, food processing, distribution, and eating out.

Claims

1. A standing pouch comprising the following laminated film (I): The laminated film (I) has a (A) heat-sealing layer, a (B) intermediate layer, and a (C) laminate layer, each containing a linear low-density polyethylene derived from petroleum, and the (A) heat-sealing layer, the (B) intermediate layer, and the (C) laminate layer all contain a biomass low-density polyethylene derived from plants. The molecular weight distribution Mw / Mn of the linear low-density polyethylene derived from petroleum is 4.0 or less, and the MFR of the linear low-density polyethylene derived from petroleum is 0.5 to 6.0 g / 10 min. The heat of fusion ΔH from 0°C to 130°C calculated from the melting curve obtained by DSC measurement of the laminated film (I) is 135 to 164 J / g, and The biomass content of the laminated film composed of the (A) heat-sealing layer, the (B) intermediate layer, and the (C) laminate layer is 5 to 10.3% by mass.

2. The standing pouch according to Claim 1, wherein the molecular weight distribution Mw / Mn of the biomass polyethylene derived from plants is 3.5 or more.

3. The standing pouch according to Claim 1 or 2, having a (D) base material layer on the side of the (C) laminate layer of the laminated film (I), either directly or via an adhesive layer.

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