Heat-fusible laminated film

Abstract

To provide a polyolefin-based laminated film that contains polypropylene, achieves reduction in environmental load through the use of biomass-derived resin, and also has low tear strength and can be heat-sealed at lower temperatures.SOLUTION: A laminated film includes (A) a seal layer, (B) a core layer, and (C) a laminate layer. The (A) seal layer and the (C) laminate layer both contain polypropylene. The (B) core layer contains linear low-density polyethylene and biomass-derived linear low-density polyethylene. The crystal melting enthalpy ΔH observed within the temperature range of 110 to 140°C during the second heating stage of the DSC curve is 28-38 J / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyolefin-based laminated film containing polypropylene, and more specifically to a laminated film that is suitably used in pharmaceutical packaging films and the like, and is particularly capable of forming easily openable packaging with low tear strength, exhibiting sufficient heat seal strength at low temperatures, and further reducing environmental impact by using biomass-derived resin. [Background technology]

[0002] In recent years, with the aim of reducing environmental impact, there has been research into replacing some of the materials that make up the resin films used in various packaging materials from resins derived from fossil fuels such as petroleum to resins derived from plants. For example, a laminated film has been proposed in which a surface layer (A), an intermediate layer (B), and a heat-seal layer (C) are laminated, wherein the surface layer (A) and the heat-seal layer (C) each contain a propylene-based resin, and the intermediate layer (B) contains linear low-density polyethylene derived from plants and linear low-density polyethylene derived from fossil fuels in predetermined proportions (see, for example, Patent Document 1).

[0003] Laminated films with the configuration described in Patent Document 1 are used in a wide range of applications, including packaging containers, but in recent years their use in medicine bag films has been expanding. When used in medicine bag films, low tear strength is required from the viewpoint of ease of opening, and it is also required that heat seal strength be achieved at lower temperatures. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-102277 [Overview of the project] [Problems that the invention aims to solve]

[0005] In view of the above technical background, the present invention aims to provide a polyolefin-based laminated film containing polypropylene, which reduces environmental impact by using biomass-derived resin, and which has even lower tear strength and can be heat-sealed at a lower temperature. [Means for solving the problem]

[0006] As a result of diligent research, the inventors have discovered that in a laminated film having (A) a seal layer, (B) a core layer, and (C) a laminate layer, wherein (A) the seal layer and (C) the laminate layer are made of polypropylene, and (B) the core layer is made of linear low-density polyethylene and biomass-derived linear low-density polyethylene, when the heat of fusion ΔH of crystals observed in the temperature range of 110 to 140°C during the second heating step of the DSC curve is within a predetermined numerical range, low tear strength can be achieved and heat sealing can be performed at low temperatures, thus completing the present invention. In other words, the present invention is [1] A laminated film having (A) a seal layer, (B) a core layer, and (C) a laminate layer, (A) The sealing layer and (C) the laminate layer contain polypropylene. (B) The core layer contains linear low-density polyethylene and linear low-density polyethylene derived from biomass, The present invention relates to the laminated film in which the heat of fusion ΔH observed in the second heating step of the DSC curve in the temperature range of 110 to 140°C is 28 to 38 J / g.

[0007] Hereinafter, [2] to [4] are all preferred embodiments or models of the present invention. [2] (B) The laminated film according to [1], wherein the content of linear low-density polyethylene derived from biomass in the core layer is 84 to 100% by mass. [3] The laminated film according to [1] or [2], wherein the polypropylene is random polypropylene. [4] The laminated film according to any one of [1] to [3], which is used for a medicine bag film.

Effects of the Invention

[0008] While maintaining the excellent properties due to the propylene polymer, the laminated film of the present invention has a significantly reduced tear strength, a significantly reduced heat seal temperature, and also reduces the environmental load in its production and the like by using a biomass-derived resin. It has practically high-value properties and combines them at a high level beyond the limits of the prior art, and can be suitably used in various applications including medicine bag films.

Modes for Carrying Out the Invention

[0009] The present invention is a laminated film having (A) a seal layer, (B) a core layer, and (C) a laminate layer, (A) The seal layer and (C) the laminate layer contain polypropylene, (B) The core layer contains linear low-density polyethylene and biomass-derived linear low-density polyethylene, The above laminated film, wherein the heat of crystal fusion ΔH observed in the temperature range of 110 to 140 °C in the second heating process of the DSC curve is 28 to 38 J / g. That is, the laminated film of the present invention contains polypropylene in its (A) seal layer and (C) laminate layer. Moreover, the laminated film of the present invention contains linear low-density polyethylene and biomass-derived linear low-density polyethylene in its (B) core layer. Hereinafter, each of the above components will be described in detail.

[0010] polypropylene The polypropylene used in at least the (A) seal layer and (C) laminate layer of the laminated film of the present invention is a resin generally manufactured and sold under the names of polypropylene, propylene polymer, and propylene-based polymer. Usually, its density is 890 to 930 kg / m 3It is a homopolymer of propylene (homopolypropylene) of a certain degree or a propylene copolymer, that is, a copolymer derived from at least one or more comonomers selected from other small amounts of α-olefins together with propylene. In the present invention, either homopolypropylene or a propylene copolymer may be used, but it is preferable to use a propylene copolymer.

[0011] When it is a copolymer, it may be a random copolymer or a block copolymer, but a random copolymer is particularly preferable. Examples of other α-olefins in the case of a propylene copolymer include α-olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, etc., with ethylene and a carbon atom number of about 4 to 20. Such other α-olefins may be copolymerized alone or in combination of two or more α-olefins.

[0012] Among these polypropylenes, from the balance of the heat resistance of the obtained laminated film and the compatibility with the (B) core layer, etc., a propylene polymer having a melting point based on a differential scanning calorimeter (DSC) in the range of 110 to 170 °C, particularly 115 to 165 °C, is preferably used.

[0013] The polypropylene used in the present invention, alone or in a blend with other resins such as an ethylene-based polymer, an ethylene·α-olefin random copolymer, a tackifying resin, etc., as long as it has the ability to form a film, its melt flow rate (MFR) is not particularly limited, but from the viewpoint of extrusion processability, etc., the melt flow rate (MFR) (ASTM D1238, 230 °C, 2160 g load) is usually in the range of 0.01 to 100 g / 10 min, preferably 0.1 to 70 g / 10 min.

[0014] As the polypropylene used in the present invention, two or more polypropylenes can also be used in combination.

[0015] The polypropylene used in the present invention can be produced using various known production methods, specifically, for example, olefin polymerization catalysts such as Ziegler-Natta catalysts and single-site catalysts. In particular, it can be produced using single-site catalysts. Single-site catalysts are catalysts with a uniform (single-site) active site, and examples include metallocene catalysts (so-called Kaminski catalysts) and Brookhart catalysts. A metallocene catalyst is a catalyst composed of a metallocene transition metal compound and at least one compound selected from the group consisting of organoaluminum compounds and compounds that react with the above metallocene transition metal compound to form an ion pair, and may be supported on an inorganic material.

[0016] Polypropylene can be blended with various additives, such as inorganic fillers like silica and talc, antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, slip agents, and pigments, as long as they do not contradict the purpose of the present invention.

[0017] Linear low-density polyethylene In the present invention, the linear low-density polyethylene used in at least the (B) core layer can be any linear low-density polyethylene that is generally known in the art. As such a linear low-density polyethylene, a copolymer of ethylene and α-olefin can be used, and it can be synthesized by a production method using a known catalyst such as a Ziegler catalyst or a metallocene catalyst.

[0018] As the α-olefin, compounds having 3 to 20 carbon atoms can be used, such as 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., and mixtures thereof may also be used. Preferably, the α-olefin is a compound having 4, 6, or 8 carbon atoms or a mixture thereof, such as 1-butene, 1-hexene, 1-octene, or a mixture thereof. However, it is also possible to increase the amount of ethylene during the polymerization process to produce α-olefins, in which case it is possible to manufacture them using virtually only ethylene as a raw material.

[0019] Linear low-density polyethylene can be a commercially available product, for example, 2040F (C6-LLDPE, MFR; 4.0, density; 0.918 g / cm³) manufactured by Ube Maruzen Polyethylene Co., Ltd. 3 ), or products such as Evolu® manufactured by Prime Polymer Co., Ltd. can be used.

[0020] The density of linear low-density polyethylene is preferably 890-940 kg / m³. 3 And more preferably, 900-930 kg / m 3 That is the case. The density of linear low-density polyethylene can be adjusted as needed by adjusting the comonomer content, and also by selecting and adjusting polymerization conditions such as catalysts and polymerization temperature.

[0021] The MFR (Metal Flow Rate) of linear low-density polyethylene (at 190°C, 2160g load) is preferably 0.1 to 15g / 10min, more preferably 0.5 to 12g / 10min, and particularly preferably 0.7 to 11g / 10min. The molecular weight-free polymer (MFR) of linear low-density polyethylene (at 190°C and 2160g load) can be adjusted as appropriate by conventionally known methods, such as by adjusting polymerization conditions like polymerization temperature or by introducing molecular weight modifiers.

[0022] Linear low-density polyethylene can be produced by conventionally known manufacturing methods using conventionally known catalysts, including multi-site catalysts such as Ziegler catalysts and single-site catalysts such as metallocene catalysts. From the viewpoint of obtaining linear low-density polyethylene that can form a high-strength film with a narrow molecular weight distribution, it is preferable to use a single-site catalyst.

[0023] The single-site catalyst described above is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activation co-catalyst. Single-site catalysts are preferred over multi-site catalysts because they have a more uniform active site structure, allowing for the polymerization of polymers with high molecular weight and high uniformity. As a single-site catalyst, metallocene catalysts are particularly preferred. A metallocene catalyst is a catalyst comprising a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, an organometallic compound if necessary, and each catalytic component of a support.

[0024] In the transition metal compounds of Group IV of the periodic table containing the ligand having the cyclopentadienyl skeleton described above, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, etc. The substituted cyclopentadienyl group has 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 bond to each other to form a ring, forming an indenyl ring, a fluorenyl ring, an azlenyl ring, or a hydrogenated version thereof. The ring formed by the bonding of substituents may further have substituents on each other.

[0025] In a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, examples of the transition metal include zirconium, titanium, and hafnium, with zirconium and hafnium being particularly preferred. The transition metal compound usually has two ligands having a cyclopentadienyl skeleton, and it is preferable that each ligand having a cyclopentadienyl skeleton is bonded to each other by a bridging group. Examples of bridging groups include alkylene groups having 1 to 4 carbon atoms, silylene groups, substituted silylene groups such as dialkylsilylene groups and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. A substituted silylene group is preferred.

[0026] In transition metal compounds of Group IV of the periodic table, typical ligands other than those having a cyclopentadienyl skeleton include hydrogen, hydrocarbon groups having 1 to 20 carbon atoms (alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, aralkyl groups, polyenyl groups, etc.), halogens, metaalkyl groups, and metaaryl groups.

[0027] The transition metal compounds of Group IV of the periodic table containing the ligand having the cyclopentadienyl skeleton described above can be used as catalyst components, either individually or as a mixture of two or more.

[0028] Co-catalysts are those that can effectively utilize the transition metal compounds of Group IV of the periodic table mentioned above as polymerization catalysts, or that can balance the ionic charge of the catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes and benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of cations containing or not containing active hydrogen groups and non-coordinating anions, lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

[0029] Transition metal compounds of Group IV of the periodic table containing ligands having a cyclopentadienyl skeleton may be used by being supported on an inorganic or organic compound support. A porous oxide of an inorganic or organic compound is preferred as the support, specifically an ion-exchangeable material such as montmorillonite. Examples include layered silicates, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, etc., or mixtures thereof.

[0030] Further organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferred.

[0031] From the viewpoint of obtaining linear low-density polyethylene with a broad molecular weight distribution and excellent flexibility and moldability, it is preferable to use multi-site catalysts such as Ziegler catalysts and Phillips catalysts. Preferred Ziegler catalysts are those commonly known as Ziegler catalysts used in the coordination polymerization of ethylene and α-olefins, such as catalysts containing titanium compounds and organoaluminum compounds. Examples include catalysts composed of titanium halide compounds and organoaluminum compounds, and catalysts composed of solid catalyst components such as titanium, magnesium, and chlorine, and organoaluminum compounds. Examples of such catalysts include catalysts comprising a catalyst component (ai) obtained by reacting an alcohol pretreatment product of an anhydrous magnesium dihalide with an organometallic compound, and an organometallic compound (bi); catalysts comprising a catalyst component (aii) obtained by reacting magnesium metal with an organic hydroxide or oxygen-containing organic compound such as magnesium, an oxygen-containing organic compound of a transition metal, and an aluminum halide, and an organometallic compound catalyst component (bii); and catalysts comprising (i) metallic magnesium and at least one selected from organic hydroxides, oxygen-containing organic compounds of magnesium, and halogen-containing compounds; (ii) at least one selected from oxygen-containing organic compounds of transition metals and halogen-containing compounds; (iii) a reaction product obtained by reacting a silicon compound with (iv) an aluminum halide compound, and an organometallic compound catalyst component (biii).

[0032] Furthermore, the Phillips catalyst can be any generally known Phillips catalyst used in the coordination polymerization of ethylene and α-olefins, such as a catalyst system containing chromium compounds like chromium oxide. Specifically, examples include catalysts in which chromium compounds such as chromium trioxide and chromate esters are supported on solid oxides such as silica, alumina, silica-alumina, and silica-titania.

[0033] Biomass-derived linear low-density polyethylene In this invention, the biomass-derived linear low-density polyethylene used in at least the (B) core layer is obtained by polymerizing ethylene produced using biomass-derived raw materials and has a density of 900-940 kg / m³. 3This refers to linear low-density polyethylene. The linear low-density polyethylene derived from biomass preferably has 10 to 30 SCBs (side chains with 1 to 5 carbon atoms, also called "short-chain branching") per 1000 carbon atoms.

[0034] The density of the biomass-derived linear low-density polyethylene is preferably 905 to 935 kg / m³. 3 Comfortably, 910-930 kg / m 3 That is the case. There are no particular restrictions on the MFR (2.16 kg, 190°C) of biomass-derived linear low-density polyethylene, but from the viewpoint of moldability, it is preferably 0.5 to 20.0 g / 10 min, more preferably 0.6 to 15.0 g / 10 min, even more preferably 0.7 to 10.0 g / 10 min, and particularly preferably 0.8 to 5.0 g / 10 min.

[0035] While there are no particular restrictions on the molecular weight distribution of biomass-derived linear low-density polyethylene, from the viewpoint of better film-forming properties, flexibility, and moldability, the molecular weight distribution (expressed as the ratio of weight-average molecular weight: Mw to number-average molecular weight: Mn, expressed as Mw / Mn) is preferably in the range of 2.5 to 10.0, more preferably 3.0 to 9.0, and even more preferably in the range of 3.5 to 8.0. This Mw / Mn can be measured by gel permeation chromatography (GPC), and more specifically, it can be measured by the method described in the examples of this application, for example.

[0036] The linear low-density polyethylene derived from biomass has one or more sharp peaks in its endothermic curve, which is measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min. The highest temperature of these peaks, i.e., the melting point, is preferably in the range of 90 to 140°C, and more preferably in the range of 100 to 130°C.

[0037] Biomass-derived linear low-density polyethylene can be a commercially available product; for example, those manufactured and sold by Braskem can be used. Specific brands such as SLH118 and SLL118 are suitable for use. The biomass-derived linear low-density polyethylene used in the present invention is obtained by polymerizing monomers containing biomass-derived ethylene (and / or biomass-derived comonomers). While it is preferable to use biomass-derived ethylene obtained by the following manufacturing method, the invention is not limited thereto. Because biomass-derived ethylene (and / or biomass-derived comonomers) is used as the raw material monomer, the resulting linear low-density polyethylene is biomass-derived. Note that the raw material monomers for polyethylene do not necessarily contain 100% by mass of biomass-derived ethylene (and biomass-derived comonomers); they may also contain non-biomass-derived ethylene or raw material monomers other than ethylene.

[0038] The method for producing biomass ethylene and other materials, which are raw materials for linear low-density polyethylene derived from biomass, is not particularly limited and can be obtained by conventionally known methods. An example of a method for producing biomass ethylene is described below.

[0039] Biomass ethylene can be produced using biomass-derived ethanol as a raw material. In particular, it is preferable to use biomass-derived fermented ethanol obtained from plant materials. The plant materials are not particularly limited, and conventionally known plants can be used. Examples include corn, sugarcane, beets, and manioc.

[0040] In the present invention, biomass-derived fermented ethanol refers to ethanol produced by contacting a culture medium containing a carbon source obtained from plant raw materials with a microorganism that produces ethanol or a product derived from its crushed material, and then purifying it. Conventional known methods such as distillation, membrane separation, and extraction can be applied to purify the ethanol from the culture medium. For example, methods such as adding benzene, cyclohexane, etc. and azeotropic distillation, or removing water by membrane separation, etc., can be used. To obtain biomass ethylene, further advanced purification may be performed at this stage, such as reducing the total amount of impurities in the ethanol to 1 ppm or less.

[0041] A catalyst is usually used when obtaining ethylene by the dehydration reaction of ethanol, but this catalyst is not particularly limited, and conventionally known catalysts can be used. A fixed-bed flow reaction is advantageous in terms of process, as it allows for easy separation of the catalyst and product, and for example, γ-alumina is preferred. This dehydration reaction is endothermic and therefore is usually carried out under heating conditions. While the heating temperature is not limited once the reaction has progressed, a temperature of 100°C or higher is preferable, more preferably 250°C or higher, and even more preferably 300°C or higher. There is no particular upper limit, but from the viewpoint of energy balance and equipment, it is preferable to have a temperature of 500°C or lower, more preferably 400°C or lower. The reaction pressure is not particularly limited, but a pressure above atmospheric pressure is preferred to facilitate subsequent gas-liquid separation. Industrially, a fixed-bed flow reaction is preferred because it facilitates catalyst separation, but a liquid-phase suspension bed, fluidized bed, etc., may also be used.

[0042] In the dehydration reaction of ethanol, the yield of the reaction depends on the amount of water contained in the ethanol supplied as a raw material. Generally, when performing a dehydration reaction, it is preferable to have no water present in order to improve the efficiency of water removal. However, in the case of the dehydration reaction of ethanol using a solid catalyst, it has been found that the amount of other olefins, especially butene, tends to increase when water is not present. This is probably because the dimerization of ethylene after dehydration cannot be suppressed without the presence of a small amount of water. The lower limit of the acceptable water content is 0.1% by mass or more, preferably 0.5% by mass or more. The upper limit is not particularly limited, but from the viewpoint of mass balance and heat balance, it is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0043] By carrying out the dehydration reaction of ethanol in this manner, a mixture of ethylene, water, and a small amount of unreacted ethanol is obtained. However, since ethylene is a gas at room temperature and below approximately 5 MPa, water and ethanol can be removed from this mixture by gas-liquid separation to obtain ethylene. This method can be carried out using known methods. The ethylene obtained by gas-liquid separation is further distilled, and there are no particular restrictions on the distillation method, operating temperature, residence time, etc., except that the operating pressure at this time is above atmospheric pressure.

[0044] When the raw material is biomass-derived fermented ethanol, the resulting ethylene contains trace amounts of impurities introduced during the ethanol fermentation process, such as carbonyl compounds like ketones, aldehydes, and esters, as well as their decomposition products like carbon dioxide, and nitrogen-containing compounds like amines and amino acids, as well as their decomposition products like ammonia. These trace amounts of impurities may pose a problem in the manufacture and use of polyethylene, and may therefore be removed by purification. The purification method is not particularly limited and can be carried out by conventionally known methods. A suitable purification operation is, for example, adsorption purification. The adsorbent used is not particularly limited and can be any conventionally known adsorbent. 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 biomass-derived fermented ethanol.

[0045] Furthermore, caustic water treatment may be used in combination as a method for purifying impurities in ethylene. If caustic water treatment is used, it is desirable to perform it before adsorption purification. In that case, it is necessary to perform a water removal treatment after the caustic treatment and before adsorption purification.

[0046] The monomers used as raw materials for biomass-derived linear low-density polyethylene may further contain ethylene and / or α-olefins derived from fossil fuels, or further contain α-olefins derived from biomass.

[0047] The above biomass-derived 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 biomass-derived raw material. Further, by including such a biomass-derived α-olefin, the resulting polyolefin has an alkyl group with a branched structure, and thus can be made more flexible than a simple linear one.

[0048] The concentration of biomass-derived ethylene in biomass-derived linear low-density polyethylene (hereinafter sometimes referred to as "biomass content") is a value obtained by measuring the content of biomass-derived carbon by radiocarbon ( 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 biomass-derived carbon can be calculated. In the present invention, when the content of 14 C in polyethylene is P 14C , the content of biomass-derived carbon P bio can be determined as follows. P bio (%) = P 14C / 105.5 × 100

[0049] In the biomass-derived linear low-density polyethylene that can be used in the present invention, theoretically, if all biomass-derived ethylene is used as the raw material for polyethylene, the biomass-derived ethylene concentration will be 100%, and the biomass content of the biomass-derived polyethylene will be 100%. However, in fossil fuel-derived polyethylene produced solely from fossil fuel-derived raw materials, the biomass-derived ethylene concentration will be 0%, and the biomass content of the fossil fuel-derived polyethylene will be 0%.

[0050] In this invention, the biomass-derived linear low-density polyethylene does not need to be 100% biomass. This is because if even a portion of the biomass-derived linear low-density polyethylene uses biomass-derived raw materials, the amount of fossil fuels used can be reduced compared to conventional methods.

[0051] In the biomass-derived linear low-density polyethylene that can be used in the present invention, the polymerization method of the monomer containing biomass-derived ethylene is not particularly limited and can be carried out by conventionally known methods. The polymerization temperature and polymerization pressure should be appropriately adjusted depending on the polymerization method and polymerization apparatus. The polymerization apparatus is also not particularly limited and conventionally known apparatus can be used. It is preferable to use a multi-site catalyst such as a Ziegler catalyst or a Philips catalyst, or a single-site catalyst such as a metallocene catalyst, as the polymerization catalyst, and to carry out the polymerization in one or more stages using one of the following methods: gas-phase polymerization, slurry polymerization, solution polymerization, or high-pressure ionic polymerization.

[0052] From the viewpoint of obtaining biomass polyethylene with a broad molecular weight distribution and excellent flexibility and moldability, it is preferable to use multi-site catalysts such as Ziegler catalysts and Phillips catalysts. Preferred Ziegler catalysts are those commonly known as Ziegler catalysts used in the coordination polymerization of ethylene and α-olefins, such as catalysts containing titanium compounds and organoaluminum compounds. Examples include catalysts composed of titanium halide compounds and organoaluminum compounds, and catalysts composed of solid catalyst components such as titanium, magnesium, and chlorine, and organoaluminum compounds. Examples of such catalysts include catalysts comprising a catalyst component (a) obtained by reacting an alcohol pretreatment product of an anhydrous magnesium dihalide with an organometallic compound, and an organometallic compound (b); catalysts comprising a catalyst component (A) obtained by reacting magnesium metal with an organic hydroxide or oxygen-containing organic compound such as magnesium, an oxygen-containing organic compound of a transition metal, and an aluminum halide, and an organometallic compound catalyst component (B); and catalysts comprising (i) metallic magnesium and at least one selected from organic hydroxides, oxygen-containing organic compounds of magnesium, and halogen-containing compounds; (ii) at least one selected from oxygen-containing organic compounds of transition metals and halogen-containing compounds; (iii) a reaction product obtained by reacting a silicon compound with (iv) an aluminum halide compound, and an organometallic compound catalyst component (B).

[0053] Furthermore, the Phillips catalyst can be any generally known Phillips catalyst used in the coordination polymerization of ethylene and α-olefins, such as a catalyst system containing chromium compounds like chromium oxide. Specifically, examples include catalysts in which chromium compounds such as chromium trioxide and chromate esters are supported on solid oxides such as silica, alumina, silica-alumina, and silica-titania.

[0054] Biomass-derived linear low-density polyethylene is usually a copolymer of ethylene and α-olefin, but it can also be produced using only ethylene as a raw material by increasing the amount of ethylene during polymerization.

[0055] As the α-olefin, compounds having 3 to 20 carbon atoms can be used, such as 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., and mixtures thereof may also be used. Preferably, the α-olefin is a compound having 4, 6, or 8 carbon atoms or a mixture thereof, such as 1-butene, 1-hexene, 1-octene, or a mixture thereof.

[0056] Biomass-derived linear low-density polyethylene may be used alone or in mixtures of two or more types. It may also be used in combination with other polymers, including other ethylene-based polymers.

[0057] In biomass-derived linear low-density polyethylene, various known additives commonly added to olefin polymers, such as antioxidants, weather stabilizers, antistatic agents, anti-fogging agents, anti-blocking agents, and slip agents (lubricants), may be added as needed, as long as they do not impair the objectives of the present invention.

[0058] The laminated film of the present invention comprises (A) a sealing layer, (B) a core layer, and (C) a laminate layer, as described below.

[0059] (A) sealing layer The (A) seal layer constituting the laminated film of the present invention contains polypropylene. By containing polypropylene in the (A) seal layer, the laminated film of the present invention can achieve desirable effects such as strength, transparency, lightness, and elastic modulus. From the viewpoint of achieving good heat sealability, it is preferable that part or all of the polypropylene contained in the (A) seal layer is random polypropylene. (A) The polypropylene content in the seal layer is preferably 80% by mass or more, more preferably 85 to 99.9% by mass, and particularly preferably 90 to 99.8% by mass.

[0060] (A) The seal layer may contain biomass-derived low-density polyethylene, including biomass-derived linear low-density polyethylene. (A) By including biomass-derived low-density polyethylene in the sealing layer, the biomass content of the laminated film can be further improved. In addition, the tear strength can be further reduced. (A) The content of biomass-derived low-density polyethylene in the seal layer is preferably 0.5% by mass or more, more preferably 1 to 9% by mass, and particularly preferably 2 to 7% by mass. (A) The method for measuring the biomass content of the seal layer is the same as that described later for (B) the biomass content of the core layer.

[0061] (A) There are no particular restrictions on the thickness of the sealing layer, but from the viewpoint of elastic modulus and the like, it is preferably 1.3 μm or more, and particularly preferably 2.5 μm or more. On the other hand, from the viewpoint of transparency and other factors, it is preferable that the thickness be 25 μm or less, and particularly preferable that it be 23 μm or less.

[0062] (B) Core layer The (B) core layer constituting the laminated film of the present invention contains linear low-density polyethylene and linear low-density polyethylene derived from biomass. (B) By including linear low-density polyethylene in the core layer, desirable effects such as high compatibility with biomass-derived linear low-density polyethylene, high transparency, a moist texture, and firmness can be achieved. (B) There are no particular restrictions on the content of linear low-density polyethylene in the core layer, but it is preferably 16% by mass or less, and particularly preferably 14% by mass or less.

[0063] (B) By including linear low-density polyethylene derived from biomass in the core layer, the biomass content is improved, reducing the environmental burden, and desirable effects such as high heat seal strength and low tear strength can be achieved. (B) The content of biomass-derived linear low-density polyethylene in the core layer is preferably 84% by mass or more, more preferably 86% by mass or more, and particularly preferably 88% by mass or more. (B) When the content of biomass-derived linear low-density polyethylene in the core layer is 84 to 100% by mass, a sufficient biomass content can be achieved, and desirable effects such as good heat sealability and low tear strength, high modulus of elasticity, and high impact strength can be achieved even more significantly. Furthermore, it becomes easier to keep the total heat of fusion ΔH of the laminated film of the present invention at 110 to 140°C within the predetermined range described later.

[0064] From the viewpoint of further enhancing the desirable effects such as the high biomass content, high transparency, good heat sealability, low tear strength, and high modulus of elasticity mentioned above, it is preferable that the thickness of the (B) core layer be greater than the thickness of the (A) seal layer and the (C) laminate layer, and particularly preferable that it be equal to or greater than the sum of the thicknesses of the (A) seal layer and the (C) laminate layer. Specifically, it is preferable that the thickness of the (B) core layer be 55% or more of the sum of the thicknesses of the (A) seal layer and the (C) laminate layer, more preferably 70% to 240%, and particularly preferable 85% to 160%. Furthermore, the thickness of the core layer (B) is preferably 2.5 to 50 μm, and more preferably in the range of 5.0 to 45 μm.

[0065] The content of biomass-derived linear low-density polyethylene can be appropriately increased or decreased, for example, by adjusting the formulation of the resin composition when manufacturing the core layer (B). The content of biomass-derived low-density polyethylene, such as linear low-density polyethylene derived from biomass, in the (B) core layer after manufacturing is, for example, radioactive carbon ( 14 C) The amount of biomass-derived carbon in the film can be measured, and this measurement result can be used to calculate the amount of biomass-derived carbon in biomass-derived low-density polyethylene.

[0066] (C) Laminate layer The laminate layer (C) constituting the laminated film of the present invention contains polypropylene. Polypropylene has high heat resistance, is lightweight, and is inexpensive; therefore, by including it, the (C) laminate layer can be made to be highly heat resistant, lightweight, and inexpensive. Furthermore, in terms of interlayer affinity, using polypropylene for the (C) laminate layer makes it easier to use polypropylene for the adjacent (B) core layer and, through it, for the (A) seal layer, resulting in a laminated film that is highly heat-resistant, lightweight, and low-cost. (C) The polypropylene content in the laminate layer is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more. (C) Random polypropylene is particularly preferred as the polypropylene in the laminate layer.

[0067] The laminate layer (C) constituting the laminated film of the present invention can be laminated with other layers, including the substrate layer (D) described later, as necessary or desired. Therefore, it is preferable that the (C) laminate layer be designed taking into consideration the lamination strength between it and other layers, including the (D) base layer. For example, it is preferable to use the same material as other layers, including the (D) base layer, and therefore it is preferable to use polypropylene or polyester-based materials, which are commonly used for the (D) base layer. Furthermore, in order to further improve the lamination strength between other layers, (C) the surface of the laminate layer (the surface opposite to the surface laminated with (B) the core layer) may be treated with corona treatment, roughening treatment, or the like.

[0068] (C) The laminate layer may contain biomass-derived low-density polyethylene, including biomass-derived linear low-density polyethylene. (C) By including biomass-derived low-density polyethylene in the laminate layer, the biomass content of the laminated film can be further improved. In addition, the tear strength can be further reduced. (C) The content of biomass-derived low-density polyethylene in the laminate layer is preferably 0.5% by mass or more, more preferably 0.8 to 20% by mass, even more preferably 1.5 to 15% by mass, and particularly preferably 2.0 to 12% by mass. (C) The method for measuring the biomass content of the laminate layer is the same as that described above for the biomass content of the core layer (B).

[0069] From the viewpoint of preventing blocking when storing the laminated film of the present invention, (C) the laminate layer may contain a blocking inhibitor. As an anti-blocking agent, powdered silica, preferably synthetic silica, etc., can be suitably used. From the viewpoint of uniformly dispersing the powdered silica in the (C) laminate layer, the powdered silica may be dispersed in a resin with excellent miscibility with the polypropylene constituting the (C) laminate layer, for example, in various polyolefins, to form a masterbatch, and then the masterbatch may be added to the polypropylene.

[0070] (C) There are no particular restrictions on the thickness of the laminate layer, but it is preferably 1 to 20 μm, and more preferably in the range of 3 to 15 μm.

[0071] (A) The seal layer, (B) the core layer, and (C) the laminate layer may contain various additives and fillers other than polypropylene, linear low-density polyethylene, and biomass-derived linear low-density polyethylene, insofar as they do not contradict the objectives of the present invention. For example, heat stabilizers, antioxidants, light stabilizers, antistatic agents, antiblocking 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 insofar as they do not contradict the objectives of the present invention.

[0072] Laminated film As described above, the laminated film of the present invention has (A) a seal layer, (B) a core layer, and (C) a laminate layer. In the laminated film of the present invention, preferably the (C) laminate layer and the (A) seal layer are laminated via the (B) core layer, but other layers may also be present.

[0073] The laminated film of the present invention can be manufactured using various known film forming methods, such as a method in which films to be (C) a laminate layer, (B) a core layer, and (A) a seal layer are formed separately in advance, and then the films are bonded together to form a laminated film; a method in which a multilayer film consisting of a (B) core layer and an (A) seal layer is obtained using a multilayer die, and then the (C) laminate layer is extruded onto the surface of the (B) core layer to form a laminated film; a method in which a multilayer film consisting of a (C) laminate layer and a (B) core layer is obtained using a multilayer die, and then the (A) seal layer is extruded onto the surface of the (B) core layer to form a laminated film; or a method in which a laminated film consisting of a (C) laminate layer, a (B) core layer, and an (A) seal layer is obtained using a multilayer die.

[0074] Furthermore, various known film forming methods can be employed, specifically, T-die-cast film forming methods and inflation film forming methods. The laminated film of the present invention and each of its constituent layers may be an unstretched film (unoriented film) or a stretched film.

[0075] The thickness of the laminated film of the present invention is not particularly limited, but from the viewpoint of ensuring practical strength, it is 5 μm or more, preferably 10 μm or more, and more preferably 15 μm or more. On the other hand, from the viewpoint of having practical flexibility even after being laminated with, for example, the (D) substrate layer, it is usually 100 μm or less, preferably 90 μm or less, and more preferably 80 μm or less.

[0076] The heat of fusion ΔH of the laminated film of the present invention at 110°C to 140°C, calculated from the melting curve of the second heating step obtained by DSC measurement, is 28 to 38 J / g. Because the heat of fusion ΔH of the crystals between 110℃ and 140℃ is within the above range, the laminated film of the present invention can achieve both good heat sealability and low tear strength at a high level that surpasses the limitations of conventional technology. The mechanism by which the above advantageous technical effects are achieved when the heat of fusion ΔH of the crystals at 110℃ to 140℃ is within the range of 28 to 38 J / g is not entirely clear. However, it can be inferred that this is related to the fact that the amount of crystalline components that melt at the above temperature range, which is sufficiently low from the film formation temperature and relatively close to the heat sealing temperature, is within an appropriate range, which allows for the formation of a resin dispersion structure that is easy to tear, and that the proportion of components that melt during heat sealing can be favorable.

[0077] The measurement of the melting curve in the second heating step using DSC, and the measurement of the heat of fusion ΔH from 110°C to 140°C from said melting curve, can be performed by conventionally known methods, and more specifically, by the method described in the embodiment of this application. The heat of fusion ΔH at 110℃ to 140℃ is more preferably 30 to 37 J / g, and even more preferably 32 to 36 J / g. The heat of fusion ΔH at 110°C to 140°C can be increased by increasing the amount of linear low-density polyethylene derived from biomass added, or by increasing the thickness of the layer to which it is added.

[0078] The laminated film of the present invention contains biomass-derived linear low-density polyethylene in (B) the core layer, and preferably (A) the seal layer and / or (C) the laminate layer, thereby reducing the amount of fossil fuels used in its manufacture and lowering the environmental burden. The biomass content of a laminated film can be calculated by weighting the biomass content of each layer by the weight of each layer. The biomass content of the laminated film can be increased or decreased as appropriate by adjusting the biomass content of each layer, and the biomass content of each layer can be increased or decreased as appropriate by adjusting the biomass content and amount of resin used in each layer. The biomass content of the laminated film of the present invention is more preferably 0.05% by mass or more, and particularly preferably 0.07% by mass or more. The biomass content of the laminated film of the present invention is preferably as high as possible, and there is no particular upper limit, but considering the physical properties of the film and cost, it is usually 60% by mass or less, and in many cases 50% by mass or less.

[0079] The laminated film of the present invention may be a stretched film or an unstretched film, From the viewpoint of improving mechanical properties, a stretched film is preferable, and a biaxially oriented film is particularly preferable. Biaxial stretching can be performed using methods such as sequential biaxial stretching, simultaneous biaxial stretching, or multi-stage stretching, as appropriate. As for the conditions for biaxial stretching, known manufacturing conditions for biaxially oriented films include, 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 in the range of 150 to 190°C, and the stretching ratio is in the range of 8 to 11 times.

[0080] (D) Base material layer If desired, the laminated film of the present invention can be laminated with the (D) substrate layer in its (C) laminate layer.

[0081] (D) There are no particular restrictions on the base layer; for example, a film commonly used for plastic packaging can be suitably used. Preferred materials for the (D) base layer include, for example, plastic films made from thermoplastic resins such as various polyethylenes, crystalline polypropylene, crystalline propylene-ethylene copolymers, crystalline polybutene-1, crystalline poly-methylpentene-1, low-, medium-, or high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ion-crosslinked olefin copolymers (ionomers); aromatic vinyl copolymers such as polystyrene and styrene-butadiene copolymers; halogenated vinyl polymers such as polyvinyl chloride and vinylidene chloride resin; nitrile polymers such as acrylonitrile-styrene copolymer and acrylonitrile-styrene-butadiene copolymer; polyamides such as nylon 6, nylon 66, para, or metaxylylene adipamide; polyesters such as polyethylene terephthalate (PET) and polytetramethylene terephthalate; various polycarbonates; and polyacetals such as polyoxymethylene. Furthermore, if the contents to be packaged are sensitive to oxygen, a film with a metal oxide or the like deposited on it, a film coated with an organic compound, or a layer made of ethylene vinyl alcohol copolymer (EVOH) resin may be provided on the above-mentioned film. Plastic films made from these materials can be used unstretched, uniaxially oriented, or biaxially oriented.

[0082] (D) These plastic films can be used as a base layer, either as a single layer or as a laminate of two or more types. Alternatively, one or more of these plastic films can be laminated with metal foil such as aluminum, paper, cellophane, etc. Preferred (D) base layers include, for example, a single-layer film made of stretched nylon film or stretched polyester film, a two-layer film made by laminating a polyolefin film such as low-density polyethylene or polypropylene with PET, and a three-layer film made by laminating PET / nylon / polyethylene. When manufacturing these laminated films, adhesives and anchoring agents may be interposed between each layer as needed. An ink layer for expressing the design may also be provided.

[0083] There are no particular restrictions on the method of laminating the (D) base material layer onto the (C) laminate layer, but for example, the (D) base material layer can be directly laminated onto the (C) laminate layer by extrusion lamination or the like. Alternatively, the (D) base material layer may be laminated onto the (C) laminate layer via an adhesive by dry lamination or the like. As the adhesive, ordinary adhesives such as urethane adhesives, acid-modified polyolefin adhesives, polyester adhesives, polyether adhesives, and polyamide adhesives can be used. (D) The thickness of the substrate layer can be set arbitrarily, but is usually selected from the range of 5 to 1000 μm, preferably 9 to 100 μm.

[0084] The laminated film of the present invention, and the laminated film obtained by laminating a (D) substrate layer onto a (C) laminate layer of the laminated film of the present invention, are preferably used in various applications and are particularly suitable for use as packaging materials.

[0085] A preferred example of such packaging material is a film for medicine bags. That is, the laminated film of the present invention achieves a high level of both good heat sealability and low tear strength, exceeding the limitations of the prior art, and is therefore particularly suitable for use as a film for medicine bags. The laminated film of the present invention (or a laminated film in which a base layer (D) is laminated onto the laminate layer (C) of the present invention) has a seal layer (A) on one of its outer layers. Therefore, by folding the laminated film in half in the center so that the seal layer (A) is on the inner side, and then heat-sealing three sides, a series of heat-sealed sections can be formed, thereby partitioning the area for storing medicine. In other words, it can be used as a medicine bag film for making medicine packaging bags. Furthermore, by using the laminated film of the present invention (or a laminated film in which a base layer (D) is laminated onto the laminate layer (C) of the present invention), a series of medicine packaging bags can be made by continuously packaging medicine using a heat-sealing type continuous packaging machine. The medications that can be packaged in medicine bags or individual drug packaging bags are not particularly limited; not only pharmaceuticals or their compounded products, but also supplements, health functional foods, foods for specified health uses, and nutritional functional foods can be included in the packaging. [Examples]

[0086] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited in any way to the following examples.

[0087] The physical properties and characteristics of the examples / comparative examples were evaluated by the following methods. (1) Molecular weight distribution (Mw / Mn) Under the following conditions, polymer samples were pretreated, and their molecular weight was measured by GPC. The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) was defined as the molecular weight distribution. i) Pretreatment 30 mg of the sample was mixed with 20 mL of the mobile phase for GPC measurement (o-dichlorobenzene), dissolved by shaking at 145°C, and the resulting solution was thermally filtered through a sintered filter with a pore size of 1.0 μm before being subjected to GPC measurement. ii) GPC Equipment: Tosoh Corporation, Gel Permeation Chromatograph HLC-8321 Columns: Manufactured by Tosoh Corporation, 7.5mm inner diameter x 30cm, 4 pieces (TSKgel GMH6-HT: 2 pieces, TSKgel GMH6-HTL: 2 pieces) Column temperature: 140℃ Detector: Differential refractometer Flow rate: 1mL / min Sampling interval: 0.5 seconds

[0088] (2) Heat of fusion Using a differential scanning calorimeter (DSC) Q100 manufactured by T.A. Instruments, approximately 5 mg of the sample was accurately weighed. Following JIS K7121, the sample was heated from -50°C to 250°C at a heating rate of 10°C / min under conditions of nitrogen gas inflow of 50 ml / min, and the thermal fusion curve was measured. The heat of fusion ΔH of the sample at 110-140°C was then determined from the obtained thermal fusion curve (during the second heating step).

[0089] (3) Tear strength Using a light-load tear tester manufactured by Toyo Seiki Seisakusho Co., Ltd., the tear strength in the MD and TD directions of the laminated films obtained in the examples and comparative examples was measured under the conditions of a measurement temperature of 23±3℃ and a measurement humidity of 50±5%RH.

[0090] (4) Heat seal strength The laminated films produced in each example / comparative example were superimposed on a 20 μm thick cellophane film with the (C) laminate layer side to create a sample film (50 mm × 150 mm). The sealing surfaces of the sample films described above were aligned, and heat-sealed for 1 second using a 5mm wide sealing bar at a temperature of 130°C and a pressure of 0.2MPa with a precision heat sealer (manufactured by Tester Industries). After cooling, a 15mm wide test piece was cut from the heat-sealed sample, and the maximum load was measured by peeling it in a 180-degree direction on a universal tensile testing machine (manufactured by A&D Co., Ltd.) at a tensile speed of 500mm / min in a constant temperature room of 23°C and 50%RH, and the heat seal strength (N / 15mm) was determined. The delamination surface was observed, and the degree of delamination was evaluated to determine which of the following categories it corresponded to. • Interfacial delamination • Aggregation and separation • Delamination • Edge breakage (cut at the boundary between the sealed and unsealed areas)

[0091] Details of each component of the resins used in the examples / comparative examples are as follows. • Linear low-density polyethylene (LLDPE) Density: 910kg / m 3 MFR (2.16kg, 190℃): 3.6g / 10min Melting point: 115℃ • Biomass-derived linear low-density polyethylene (B-LLDPE) Manufactured by Braschem, product name: SLH118 MFR (2.16kg, 190℃): 1.0g / 10min Density: 916kg / m 3 Molecular weight distribution (Mw / Mn): 4.43 Random Polypropylene-1 (rPP-1) Density: 910kg / m 3 MFR (2.16kg, 210℃): 7.0g / 10min Melting point: 131℃ Random polypropylene-2 ​​(rPP-2) Density: 900kg / m 3 MFR (2.16kg, 210℃): 7.0g / 10min Melting point: 125℃

[0092] (Comparative Example 1) The components constituting each layer were supplied to separate extruders according to the formulations shown in Table 1, and a 50 μm thick laminated film was formed by the T-die method, consisting of a three-layer co-extruded film with the configuration of (A) seal layer / (B) core layer / (C) laminate layer. The laminated film was then subjected to corona treatment. The thickness ratio of each layer was (A) seal layer:(B) core layer:(C) laminate layer = 25:50:25. The obtained laminated films were evaluated according to the methods described in (2) to (4) above. The results are shown in Table 1.

[0093] (Comparative Example 2, and Examples 1 to 2) (B) A laminated film was prepared and evaluated in the same manner as in Comparative Example 1, except that the composition of the core layer was changed as shown in Table 1. The results are shown in Table 1.

[0094] [Table 1] [Industrial applicability]

[0095] The laminated film of the present invention maintains the excellent properties derived from the propylene polymer while significantly reducing tear strength and heat sealing temperature. Furthermore, by using biomass-derived resin, it reduces the environmental burden during its manufacture, etc., thus possessing a high level of practical value. It is suitable for various packaging films, including medicine bags, and has high applicability in various industrial fields such as pharmaceuticals, healthcare, nursing, caregiving, accommodation, agriculture, food, and distribution.

Claims

1. A laminated film having (A) a seal layer, (B) a core layer, and (C) a laminate layer, (A) the sealing layer and (C) the laminate layer contain polypropylene; (B) the core layer contains linear low-density polyethylene and biomass-derived linear low-density polyethylene; The above laminated film has a heat of crystalline fusion ΔH of 28 to 38 J / g observed in the temperature range of 110 to 140° C. in the second heating stroke of the DSC curve.

2. The laminated film according to claim 1, wherein the content of the biomass-derived linear low-density polyethylene in the core layer (B) is 84 to 100% by mass.

3. The laminated film according to claim 1 or 2, wherein the polypropylene is a random polypropylene.

4. The laminated film according to claim 1 or 2, which is used as a film for a medicine bag.