Heat-fusible laminate film

Abstract

To provide a heat-fusible laminate film which is suitably used for a lid material of a resin coat paper container, can achieve adequate heat sealability between a resin coat paper container and the laminate film, and is also excellent in film formation property.SOLUTION: A laminate film has (A) a seal layer, (B) a core layer and (C) a laminate layer, where (A) the seal layer contains polypropylene and an ethylene-propylene copolymer, (B) the core layer and (C) the laminate layer each contains linear low-density polyethylene, and the content of the ethylene-propylene copolymer of (A) the seal layer is 35-70 mass%.SELECTED DRAWING: None

Description

Technical field

[0001] The present invention relates to a heat-sealable laminated film, and more specifically, it is suitably used as a lid material for a resin-coated paper container, and is particularly capable of achieving appropriate heat-sealing performance with the resin-coated paper container. This invention relates to a heat-adhesive laminated film that has excellent film formability. [Background technology]

[0002] The use of paper containers has become commonplace as containers for various foods such as dairy products such as yogurt, natto, and instant noodles, in response to demands for clearer printing due to the diversification of designs and environmental issues at the time of disposal. ing. The inner surface of the paper container is usually coated with various resins such as polyethylene for the purpose of water resistance, etc. In order to heat seal the resin coat layer of the resin coated paper container, a laminated film having a sealing layer is used as the lid material. (For example, see Patent Document 1.)

[0003] In recent years, the demand for the performance of resin-coated paper containers has increased further, and it is possible to achieve appropriate heat-sealing performance with resin-coated paper containers, more specifically, to achieve sufficient heat-sealing strength at relatively low temperatures, and to ensure that the paper remains intact when opened. There is a need for a lidding material that has heat-sealing performance that allows the lidding material to be peeled off from the container without causing paper peeling or the like. In addition, from the viewpoint of production efficiency and storage convenience, it is also required to suppress sticking of the film to the roll during film formation due to stickiness of the film, and to appropriately prevent blocking of the film. [Prior art documents] [Patent document]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-058642 [Summary of the invention] [Problem to be solved by the invention]

[0005] In view of the above technical background, the present invention is a heat-sealing material that can be suitably used as a lid material for resin-coated paper containers, can achieve appropriate heat-sealing performance especially with resin-coated paper containers, and has excellent film-forming properties. An object of the present invention is to provide a fusible laminated film. [Means to solve the problem]

[0006] As a result of extensive studies, the present inventors have discovered a laminated film having (A) a sealing layer, (B) a core layer, and (C) a laminate layer, in which (A) the sealing layer is made of polypropylene and ethylene-propylene copolymer. In the above laminated film in which (B) the core layer and (C) the laminate layer each contain linear low density polyethylene, the content of the above ethylene-propylene copolymer in the (A) sealing layer is The inventors have discovered that by setting the temperature within a specific range, it is possible to achieve appropriate heat-sealing performance with the resin-coated paper container, as well as excellent film-forming properties, and have completed the present invention. That is, the present invention [1] A laminated film having (A) a sealing layer, (B) a core layer, and (C) a laminate layer, (A) the sealing layer contains polypropylene and ethylene-propylene copolymer, (B) the core layer and (C) the laminate layer each contain linear low density polyethylene, (A) The above laminated film, wherein the content of the ethylene-propylene copolymer in the seal layer is 35 to 70% by mass.

[0007] [2] to [4] below are all preferred aspects or embodiments of the present invention. [2] The density of the ethylene-propylene copolymer is 850 to 900 kg / m 3 The laminated film according to [1]. [3] The laminated film according to [1] or [2], wherein the polypropylene is homopolypropylene. [Four] The laminated film according to any one of [1] to [3], which is used for sealing a polyethylene resin-coated paper container.

Effect of the invention

[0008] The laminated film of the present invention can achieve appropriate heat-sealing performance with resin-coated paper containers as well as excellent film-forming properties, achieving properties that have high practical value by exceeding the limits of conventional technology. It has a high level of functionality and can be suitably used in a variety of applications including food packaging. [Details for carrying out the invention]

[0009] The present invention is a laminated film having (A) a sealing layer, (B) a core layer, and (C) a laminate layer, (A) the sealing layer contains polypropylene and ethylene-propylene copolymer, (B) the core layer and (C) the laminate layer each contain linear low density polyethylene, (A) The laminated film, wherein the content of the ethylene-propylene copolymer in the seal layer is 35 to 70% by mass. That is, the laminated film of the present invention contains polypropylene and an ethylene-propylene copolymer in its (A) sealing layer, and the content of the ethylene-propylene copolymer in the sealing layer (A) is from 35 to 70% by mass. %.

[0010] polypropylene The polypropylene used in at least (A) the sealing layer of the laminated film of the present invention is a resin generally manufactured and sold under the names of polypropylene, propylene polymer, propylene polymer, etc., and usually has a density of 890 to 930 kg. / m 3 It is a homopolymer of propylene (homopropylene) or a propylene copolymer, that is, a copolymer derived from propylene and at least one comonomer selected from a small amount of other α-olefins. In the present invention, both homopropylene and propylene copolymers can be used, but homopropylene is particularly preferably used. When it is a copolymer, it may be a random copolymer or a block copolymer. Other α-olefins in the case of propylene copolymers include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, etc. Examples include α-olefins having about 4 to 20 carbon atoms. Such other α-olefins may be copolymerized singly or in combination of two or more α-olefins.

[0011] Among these polypropylenes, polypropylenes having a melting point in the range of 110 to 170°C, particularly 115 to 165°C based on differential scanning calorimetry (DSC) are preferably used from the viewpoint of heat resistance of the resulting laminated film.

[0012] As long as the polypropylene used in the present invention has film-forming ability alone or in a blend with other resins such as ethylene polymers, ethylene / α-olefin random copolymers, and tackifying resins, its melt flow rate (MFR) is not particularly limited, but from the viewpoint of extrusion processability, for example, it is preferable that the melt flow rate (MFR) (ASTM D1238, 230°C, 2160g load) is within the range of 0.01 to 100g / 10 minutes. , more preferably within the range of 0.1 to 70 g / 10 minutes.

[0013] As the polypropylene used in the present invention, two or more types of polypropylene can also be used in combination.

[0014] The polypropylene used in the present invention can be produced by various known production methods, specifically, for example, using an olefin polymerization catalyst such as a Ziegler-Natta catalyst or a single-site catalyst. In particular, it can be produced using a single site catalyst. Single site catalysts are catalysts in which the active sites are uniform (single site), and include, for example, metallocene catalysts (so-called Kaminski catalysts) and Brookhart catalysts. A metallocene catalyst is a catalyst consisting of a metallocene transition metal compound and at least one compound selected from the group consisting of an organic aluminum compound and a compound that reacts with the metallocene transition metal compound to form an ion pair. It may be supported.

[0015] Polypropylene may contain various inorganic fillers such as silica and talc, antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, slip agents, pigments, etc., as long as they do not contradict the purpose of the present invention. Additives can be added.

[0016] Ethylene-propylene copolymer

[0017] The ethylene-propylene copolymer used in at least the seal layer (A) of the laminated film of the present invention is a copolymer having a structural unit derived from ethylene and a structural unit derived from propylene. The ethylene-propylene copolymer only needs to have a constitutional unit derived from ethylene and a constitutional unit derived from propylene, and may have other constitutional units. It may be composed only of structural units derived from ethylene and structural units derived from propylene.

[0018] When the ethylene-propylene copolymer has a structural unit derived from ethylene and a structural unit other than the structural unit derived from propylene, there is no particular restriction on the other structural units, and ethylene and propylene may be combined with each other. Constituent units derived from copolymerizable monomers can be used as appropriate. Other structural units mentioned above include structural units derived from α-olefins other than propylene such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1,4-hexadiene, dicyclopentadiene, Building blocks derived from non-conjugated dienes such as 5-ethylidene-2-norbornene can be used.

[0019] There is no particular limit to the density of ethylene-propylene copolymer, but it is usually between 850 and 900 kg / m. 3 and preferably 851 to 885 kg / m 3 and particularly preferably from 852 to 880 kg / m 3 It is. From the perspective of appropriately realizing the effects of the present invention, the density is 880 kg / m 3 It is preferable to use the following densities classified as so-called ethylene-propylene rubber.

[0020] There is no particular restriction on the melting point of the ethylene-propylene copolymer, but it is usually 100°C or lower, preferably 90°C or lower, and particularly preferably 80°C or lower.

[0021] There is no particular limit to the MFR of the ethylene-propylene copolymer, but the MFR measured at 230°C and a load of 2.16 kg is usually 0.1 to 10.0 g / min, preferably 0.2 to 9.5 g / min, and particularly preferably. is 0.3 to 9.0g / min.

[0022] The ethylene-propylene copolymer can be produced by a known polymerization method using a known olefin polymerization catalyst. Examples include slurry polymerization, solution polymerization, bulk polymerization, and gas phase polymerization using complex catalysts such as Ziegler-Natta catalysts, metallocene complexes, and non-metallocene complexes. Further, the various catalysts and manufacturing methods described and exemplified in the manufacturing method of linear low-density polyethylene below can also be used as appropriate in the ethylene-propylene copolymer.

[0023] Linear low density polyethylene As the linear low-density polyethylene used in at least the (B) core layer and (C) laminate layer in the present invention, those generally known in the technical field as linear low-density polyethylene may be appropriately used. can. As such a linear low density polyethylene, a copolymer of ethylene and an α-olefin can be used, and one synthesized by a production method using a known catalyst such as a Ziegler catalyst or a metallocene catalyst can be used. can.

[0024] 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- Examples include decene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, and mixtures thereof may also be used. The α-olefin is preferably 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. Of course, α-olefin can also be produced by increasing the amount of ethylene in the polymerization process, and in this case, it can also be produced using substantially only ethylene as a raw material.

[0025] The linear low-density polyethylene may be a commercially available product, for example, 2040F (C 6 -LLDPE, MFR; 4.0, density; 0.918g / cm 3 ), Evolu (registered trademark) manufactured by Prime Polymer Co., Ltd., etc. can be used.

[0026] The density of the linear low density polyethylene is preferably 890 to 940 kg / m 3 more preferably 900~930kg / m 3 It is. The density of linear low density polyethylene can be adjusted appropriately by adjusting the comonomer content, and can also be adjusted appropriately by selecting and adjusting polymerization conditions such as catalyst and polymerization temperature.

[0027] The MFR (190°C, 2160g load) of linear low density polyethylene is preferably 0.1 to 15g / 10min, more preferably 0.5 to 12g / 10min, and preferably 0.7 to 11g / 10min. Particularly preferred. The MFR (190°C, 2160g load) of linear low-density polyethylene can be adjusted appropriately by conventionally known methods, such as adjusting polymerization conditions such as polymerization temperature or introducing a molecular weight regulator. It is possible to adjust with.

[0028] Linear low density polyethylene can be produced by a conventionally known production method using a conventionally known catalyst such as a multi-site catalyst such as a Ziegler catalyst or a single-site catalyst such as a metallocene catalyst. From the viewpoint of obtaining linear low-density polyethylene that has a narrow molecular weight distribution and can form a high-strength film, it is preferable to use a single-site catalyst.

[0029] The above-mentioned single-site catalyst is a catalyst that can form a uniform active species, and is usually prepared by bringing a metallocene transition metal compound or a non-metallocene transition metal compound into contact with an activation cocatalyst. . Single-site catalysts are preferable compared to multi-site catalysts because they have a more uniform active site structure and can polymerize a polymer with a high molecular weight and a highly uniform structure. As the single site catalyst, it is particularly preferable to use a metallocene catalyst. The metallocene 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. be.

[0030] In the transition metal compound of Group IV of the periodic table containing the above-mentioned ligand having a cyclopentadienyl skeleton, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, etc. . Examples of the substituted cyclopentadienyl group include a hydrocarbon group having 1 to 30 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group, a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, and a halosilyl group. It has at least one substituent selected from groups. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may combine with each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenated product thereof. may be formed. The ring formed by bonding the substituents to each other may further have a substituent.

[0031] 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, hafnium, etc., and zirconium and hafnium are particularly preferred. The transition metal compound usually has two cyclopentadienyl skeleton-containing ligands, and each of the cyclopentadienyl skeleton-containing ligands is preferably bonded to each other via a crosslinking group. Examples of the crosslinking group include alkylene groups having 1 to 4 carbon atoms, substituted silylene groups such as silylene groups, dialkylsilylene groups, and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. Preferably, it is a substituted silylene group.

[0032] 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 group, aryl group, alkylaryl group, aralkyl group, polyenyl group, etc.), halogen, metaalkyl group, metaaryl group, etc.

[0033] One or a mixture of two or more of the transition metal compounds of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton can be used as a catalyst component.

[0034] The co-catalyst is one that can make the transition metal compound of Group IV of the periodic table effective as a polymerization catalyst, or can balance the ionic charges in a catalytically activated state. As a co-catalyst, organoaluminumoxy compounds such as benzene-soluble aluminoxane, benzene-insoluble organoaluminumoxy compounds, ion-exchanged layered silicates, boron compounds, cations containing or not containing active hydrogen groups, and non-coordinating anions can be used. Examples include ionic compounds, lanthanoid salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

[0035] A transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton may be used by being supported on an inorganic or organic compound carrier. The carrier is preferably a porous oxide of an inorganic or organic compound, specifically, an ion-exchangeable oxide such as montmorillonite. layered silicate, SiO 2 ,Al 2 O 3 , MgO, ZrO 2 , TiO 2 , B 2 O 3 , CaO, ZnO, BaO, ThO 2 etc. or mixtures thereof.

[0036] Furthermore, examples of organometallic compounds that may be used as necessary include organoaluminum compounds, organomagnesium compounds, organozinc compounds, and the like. Among these, organic aluminum is preferably used.

[0037] From the viewpoint of obtaining linear low-density polyethylene with a wide molecular weight distribution and excellent flexibility and moldability, it is preferable to use a multisite catalyst such as a Ziegler catalyst or a Phillips catalyst. Preferred Ziegler catalysts include 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, and those containing titanium halide compounds and organic aluminum compounds. Examples include a catalyst made of an aluminum compound, a catalyst made of a solid catalyst component made of titanium, magnesium, chlorine, etc., and an organic aluminum compound. More specifically, such a catalyst includes a catalyst component (ai) obtained by reacting a titanium compound with a reaction product of an alcohol pretreated product of anhydrous magnesium dihalide and an organometallic compound, and an organometallic compound ( bi), a catalyst component (aii) 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 an organometallic compound. a catalyst consisting of a catalyst component (bii); (i) at least one member selected from magnesium metal and an organic hydroxide compound, an oxygen-containing organic compound of magnesium, and a halogen-containing compound; (ii) an oxygen-containing organic compound of a transition metal and a halogen; At least one member selected from the containing compounds, (iii) a reactant obtained by reacting a silicon compound, (iv) a solid catalyst component obtained by reacting an aluminum halide compound (aiii), and a catalyst component of an organometallic compound. (biii) and the like can be exemplified.

[0038] In addition, the Phillips catalyst may be one generally known as a Phillips catalyst used for coordination polymerization of ethylene and α-olefin, for example, a catalyst system containing a chromium compound such as chromium oxide, and specifically, Examples include catalysts in which a chromium compound such as chromium trioxide or chromate ester is supported on a solid oxide such as silica, alumina, silica-alumina, or silica-titania.

[0039] (A) Seal layer The seal layer (A) constituting the laminated film of the present invention is a case that is fused to other members such as resin-coated paper containers when forming packaging films, packaging bags, etc. using the laminated film of the present invention. There are many. For this reason, it is preferable to use a resin with a low melting point so that high sealing strength can be obtained. Preferred examples of low-melting point resins include high-density polyethylene, high-pressure low-density polyethylene, ethylene polymers such as ethylene / α-olefin random copolymers; aliphatic hydrocarbon resins and alicyclic hydrocarbon resins. , aromatic hydrocarbon resins, polyterpene resins, rosins, styrene resins, tackifying resins such as coumaron-indene resins, etc., but in particular (A) polypropylene and ethylene constituting the sealing layer. -High sealing strength can be achieved by using a propylene copolymer with a low melting point.

[0040] As mentioned above, the seal layer (A) contains polypropylene and an ethylene-propylene copolymer. (A) The content of the ethylene-propylene copolymer in the seal layer is 35 to 70% by mass. The content of the ethylene-propylene copolymer in the seal layer is preferably from 35 to 60% by mass, particularly preferably from 35 to 50% by mass. (A) By having an ethylene-propylene copolymer content of 35% by mass or more in the sealing layer, the laminated film of the present invention achieves high heat sealing strength with other members such as resin-coated paper containers. can do. Further, high lamination strength can be achieved between the core layer (B) containing linear low density polyethylene. (A) Since the content of the ethylene-propylene copolymer in the seal layer is 70% by mass or less, the laminated film of the present invention can suppress sticking to the roll during film formation due to stickiness of the film, and Blocking of the film is also properly prevented. (A) Details of the ethylene-propylene copolymer used in the seal layer are as described above.

[0041] (A) There is no particular limit to the content of polypropylene in the sealing layer, but from the viewpoint of heat sealing strength with other members such as resin-coated paper containers or lamination strength with the core layer, it should be 20 to 60% by mass. Preferably, it is from 30 to 60% by mass, particularly preferably from 30 to 60% by mass. (A) The details of the polypropylene used in the sealing layer are as described above.

[0042] (A) The thickness of the sealing layer is not particularly limited, but from the viewpoint of ease of opening, etc., it is preferably 0.5 μm or more, and particularly preferably 0.8 μm or more. On the other hand, from the viewpoint of stringiness, etc., the thickness is preferably 20.0 μm or less, particularly preferably 15.0 μm or less.

[0043] From the viewpoint of preventing blocking during storage of the laminated film of the present invention, the sealing layer (A) may contain an anti-blocking agent. As the antiblocking agent, powdered silica, preferably synthetic silica, etc. can be suitably used. From the viewpoint of uniformly dispersing the powdered silica in the (A) sealing layer, the powdered silica is dispersed in a resin that has excellent miscibility with the ethylene-propylene copolymer that constitutes the (A) sealing layer. For example, it may be dispersed in low density polyethylene to form a masterbatch, and then the masterbatch may be added to the ethylene-propylene copolymer.

[0044] (B) Core layer The core layer (B) constituting the laminated film of the present invention contains linear low-density polyethylene. (B) Since the core layer contains linear low-density polyethylene, the laminated film of the present invention can be provided with excellent properties such as transparency, flexibility, and lightness. In addition, since the (B) core layer contains linear low-density polyethylene, the sealing layer (A) containing the same ethylene-based resin, ethylene-propylene copolymer, and the same linear low-density polyethylene High lamination strength can be achieved between the (C) laminate layer containing (B) The content of linear low density polyethylene in the core layer is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0045] Among the layers constituting the laminated film of the present invention, it is preferable that (A) the sealing layer is designed to obtain appropriate sealing strength, and (C) the laminate layer is designed to provide the laminate layer with (D) the base material layer, etc. While it is preferable to design with strength etc. in mind, the (B) core layer has relatively few such restrictions, so it is possible to provide the desired physical properties and performance to the entire laminated film of the present invention, such as mechanical properties. It is possible to design with priority given to giving. In this case, it is preferable that the thickness of (B) the core layer be greater than the thickness of (A) the seal layer and (C) the laminate layer; It is particularly preferable that the thickness be greater than the sum of the thicknesses. Specifically, it is preferable that the thickness ratio of each layer is seal layer / core layer / laminate layer=7±4% / 75±10% / 18±6%. The thickness of the core layer (B) is preferably in the range of 10 to 85 μm, more preferably in the range of 15 to 80 μm.

[0046] (C) Laminate layer The laminate layer (C) constituting the laminate film of the present invention contains linear low-density polyethylene. (C) Since the laminate layer contains linear low-density polyethylene, the laminated film of the present invention can be provided with excellent properties such as transparency, flexibility, and lightness. Furthermore, since the (C) laminate layer contains linear low-density polyethylene, high lamination strength can be achieved between it and the (B) core layer, which also contains linear low-density polyethylene. (C) The content of linear low density polyethylene in the laminate layer is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0047] The laminate layer (C) can be laminated with other layers including the base material layer (D) described below, as necessary or desired. Therefore, it is preferable to design the (C) laminate layer in consideration of the lamination strength between it and other layers including the (D) base layer. For example, it is preferable to use the same type of material as other layers including the (D) base layer, and therefore polyethylene, polypropylene, or polyester materials, which are preferably used for the (D) base layer, are used. It is preferable to use In addition, in order to further improve the lamination strength between other layers, the surface of (C) laminate layer (the surface opposite to the surface laminated with (B) core layer) is subjected to corona treatment and surface roughening treatment. Processing such as the following may also be performed.

[0048] From the viewpoint of preventing blocking during storage of the laminated film of the present invention, the laminate layer (C) may contain an anti-blocking agent. As the antiblocking agent, powdered silica, preferably synthetic silica, etc. can be suitably used. From the viewpoint of uniformly dispersing powdered silica in the (C) laminate layer, powdered silica is mixed in a resin that has excellent miscibility with the linear low-density polyethylene that constitutes the (C) laminate layer. For example, it may be dispersed in low density polyethylene to form a masterbatch, and then the masterbatch may be added to petroleum-derived linear low density polyethylene.

[0049] (C) The thickness of the laminate layer is not particularly limited, but it is preferably in the range of 1 to 20 μm, more preferably in the range of 3 to 15 μm.

[0050] All of (A) the seal layer, (B) the core layer, and (C) the laminate layer may contain various additives, fillers, such as heat stabilizers, antioxidants, light Adding 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. I can do it. Furthermore, thermoplastic resins, thermoplastic elastomers, rubbers, hydrocarbon resins, petroleum resins, etc. other than the above-mentioned essential resin components may be blended within a range that does not contradict the purpose of the present invention.

[0051] 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, the (C) laminate layer and (A) sealing layer are preferably laminated via the (B) core layer, but other layers may be present.

[0052] In producing the laminated film of the present invention, various known film forming methods are used, for example, after forming the films that will become (C) the laminate layer, (B) the core layer, and (A) the sealing layer in advance, After obtaining a multilayer film consisting of (B) core layer and (A) sealing layer using a multilayer die, a (C) laminate layer is attached on the surface of the (B) core layer. A method of extruding to make a laminated film, using a multilayer die to obtain a multilayer film consisting of (C) a laminate layer and (B) a core layer, and then extruding (A) a sealing layer on the surface of the (B) core layer. A method of forming a laminated film, or a method of using a multilayer die to obtain a laminated film consisting of (C) a laminate layer, (B) a core layer, and (A) a sealing layer can be adopted.

[0053] Further, as a film forming method for producing the laminated film of the present invention, various known film forming methods, specifically, a T-die cast film forming method and a blown film forming method may be employed. The laminated film of the present invention and each layer constituting it may be an unstretched film (unstretched film) or a stretched film.

[0054] The thickness of the laminated film of the present invention is not particularly limited, but from the viewpoint of ensuring practical strength, etc., it is 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more. On the other hand, from the viewpoint of having practical flexibility even after being laminated with (D) the base material layer, on the other hand, the thickness is usually 100 μm or less, preferably 90 μm or less, and more preferably 80 μm or less.

[0055] Although the laminated film of the present invention may be a stretched film or an unstretched film, it is preferably an unstretched film from the viewpoints of manufacturing cost, flexibility, and the like. From the viewpoint of improving mechanical properties, a stretched film is preferred, and a biaxially stretched film is particularly preferred. For the biaxial stretching, methods such as sequential biaxial stretching, simultaneous biaxial stretching, and multistage stretching are appropriately employed. The conditions for biaxial stretching are known manufacturing conditions for biaxially stretched films, for example, in the sequential biaxial stretching method, the longitudinal stretching temperature is 100 ° C to 145 ° C, the stretching ratio is in the range of 4 to 7 times, the transverse stretching temperature is For example, the temperature may be 150 to 190°C, and the stretching ratio may be 8 to 11 times.

[0056] (D) Base material layer If desired, the laminated film of the present invention can be laminated with the (D) base material layer in its (C) laminate layer.

[0057] There are no particular limitations on the base layer (D), and for example, films commonly used for plastic packaging can be suitably used. Preferred materials for the base layer (D) include, for example, crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly4-methylpentene-1, low-, medium-, or Polyolefins such as high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ionically crosslinked olefin copolymer (ionomer); polystyrene, styrene-butadiene copolymer, etc. Aromatic vinyl copolymers; halogenated vinyl polymers such as polyvinyl chloride and vinylidene chloride resins; nitrile polymers such as acrylonitrile-styrene copolymers and acrylonitrile-styrene-butadiene copolymers; nylon 6, nylon 66, Plastic films made of thermoplastic resins such as polyamides such as para- or metaxylylene adipamide; polyesters such as polyethylene terephthalate (PET) and polytetramethylene terephthalate; various polycarbonates; and polyacetals such as polyoxymethylene. can be mentioned. In addition, if the contents to be packaged are sensitive to oxygen, the above film may be coated with a metal oxide, etc., 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 after being unstretched, uniaxially stretched, or biaxially stretched.

[0058] (D) As the base material layer, these plastic films can be used as a single layer or as a laminate of two or more kinds, and one or more of these plastic films and aluminum can be used. It can also be constructed by laminating metal foils such as, paper, cellophane, etc. Preferred base layer (D) is, for example, a stretched nylon film, a single layer film made of a stretched polyester film, a two-layered film laminated with PET and a polyolefin film such as low density polyethylene or polypropylene, or PET / nylon / polyethylene. Examples include laminated three-layer films. When manufacturing these laminated films, an adhesive or an anchor agent may be interposed between each layer as necessary. Further, an ink layer expressing a design may be provided.

[0059] There are no particular limitations on the method of laminating the (D) base material layer on the (C) laminate layer, but the (D) base material layer can be directly laminated on the (C) laminate layer, for example, by extrusion lamination or the like. Alternatively, the (D) base material layer may be laminated on the (C) laminate layer via an adhesive by dry lamination or the like. As the adhesive, common adhesives such as urethane adhesive, acid-modified polyolefin adhesive, polyester adhesive, polyether adhesive, polyamide adhesive, etc. can be used. (D) The thickness of the base layer can be set arbitrarily, but is usually selected from the range of 5 to 1000 μm, preferably 9 to 100 μm.

[0060] The laminated film of the present invention and the laminated film in which the (C) laminate layer and (D) base layer of the laminated film of the present invention are laminated are preferably used in various applications, and are particularly suitable for use as packaging materials. .

[0061] A preferable example of such a packaging material is a lid material. That is, the laminated film of the present invention and the laminated film in which the (D) base material layer is laminated on the (C) laminate layer of the laminated film of the present invention can be used as a lid material using the (A) sealing layer as the innermost layer of a container. I can do it. Since the laminated film of the present invention can achieve appropriate heat-sealing performance with a resin-coated paper container, it can be particularly suitably used as a lid material for a resin-coated paper container. When used as a container lid material, the laminated film of the present invention may be used as the lid material as it is, or may be printed. Furthermore, it may be laminated with a printed or unprinted base material layer (D) to form a lid material. Further, depending on the application, the lid material may be cut in advance to match the shape of the container. When used as a container lid material, it is preferably used in combination with the (D) base material layer.

[0062] The laminated film of the present invention can form a heat-sealing layer by heat-sealing the (A) sealing layer to various adherends. As such an adherend, a resin-coated paper container is particularly preferred. Examples of the resin used for the resin coating of the resin-coated paper container include polyethylene, polypropylene, polystyrene, polyester, polycarbonate, polyvinyl chloride, etc., and polyethylene is particularly preferred. Resin-coated paper containers can be of various shapes, such as trays, cups, bottles, films, sheets, etc.

[0063] Although there are no particular restrictions on what can be stored in a packaging container such as a resin-coated paper container, it can be preferably used for packaging foods, medicines, medical instruments, daily necessities, miscellaneous goods, and the like. Taking advantage of the excellent heat-sealing properties of the laminated film of the present invention, it is particularly suitable for use in food packaging containers.

Example

[0064] The present invention will be specifically described below with reference to Examples / Comparative Examples. Note that the present invention is not limited to the following examples in any way.

[0065] Evaluation of physical properties and characteristics in Examples / Comparative Examples was performed by the following method. (1) Heat seal strength A sample film (50 mm x 60 mm) was prepared by hand laminating the laminated film produced in each Example / Comparative Example with a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm on the (C) laminate layer side surface. The above sample film was placed on a test piece (50 mm x 30 mm) cut from the side of a heat-insulating embossed paper container SMP-900E-2 manufactured by Tokan Kogyo Co., Ltd., and heated to 160°C using a precision heat sealer (manufactured by Tester Sangyo). ℃ or 180℃ with a pressure of 0.2MPa using a 5mm wide seal bar for 1.0 seconds, then let it cool. Then, cut a 15mm wide test piece from the heat sealed sample and store it in a constant temperature room at 23℃ and 50% RH. At a tensile speed of 500 mm / min, the sample was peeled in a 180-degree direction using a universal tensile testing machine (manufactured by A&D Co., Ltd.), and the maximum load was measured, which was defined as the heat seal strength (N / 15 mm). The peeled surface was observed and the peeled state was evaluated based on the following criteria. ○: Peeling occurred due to cohesive peeling, and paper peeling from the paper container did not occur. Δ: Peeling occurred due to cohesive peeling, and partial paper peeling occurred from the paper container. (2) Film formability The film formability of the laminated films produced in each Example / Comparative Example was confirmed during film formation. ○: A laminated film could be obtained without any problems in film formability. ×: The laminated film was sticky, and sticking to the roll and blocking between the films occurred, making it impossible to collect samples.

[0066] Details of each component such as resin used in Examples / Comparative Examples are as follows. ·Linear low density polyethylene-1 (LLDPE-1) Density: 931kg / cm 3 MFR (2.16kg, 190℃): 2.1g / 10min Melting point: 123℃ ·Linear low density polyethylene-2 ​​(LLDPE-2) Density: 924kg / cm 3 MFR (2.16kg, 190℃): 3.8g / 10min Melting point: 120℃ ·Homopolypropylene (h-PP) Density: 910kg / cm 3 MFR (2.16kg, 230℃): 7.0g / 10min Melting point: 161℃ ·Ethylene-propylene copolymer (EPR) Ethylene content: 73% by weight Density: 860kg / m 3 MFR (2.16kg, 230℃): 7.0g / 10 minutes. ·Linear low density polyethylene anti-blocking agent (LLDPE AB agent) ·Mixture of linear low density polyethylene and synthetic zeolite Density: 0.913kg / cm 3 MFR (2.16kg, 190℃): 3.8g / 10min Melting point: 113℃

[0067] (Example 1) The components constituting each layer are supplied to separate extruders in the formulation shown in Table 1, and the T-die method is used to create a structure consisting of (A) seal layer / (B) core layer / (C) laminate layer. A three-layer coextruded laminated film with a thickness of 30 μm was produced. The thickness ratio of each layer was (A) seal layer: (B) core layer: (C) laminate layer = 11:60:29. Using the obtained laminated film, seal strength, peeling state, and film formability were evaluated. Film formability was also evaluated during the production of the laminated film. The results are shown in Table 1.

[0068] (Examples 2 to 7 and Comparative Example 1) (C) A laminated film was produced and evaluated in the same manner as in Example 1, except that the composition of the seal layer was changed to that shown in Table 1. The results are shown in Table 1. In Comparative Example 1, the film formability was poor, so it was not possible to obtain a sample for use in evaluating heat seal strength.

[0069]

table 1

[0070] The laminated film of the present invention has a high level of properties that have high practical value, such as being able to achieve appropriate heat-sealing performance with resin-coated paper containers as well as excellent film formability. It is suitable for various uses including food containers, and has high applicability in various industrial fields such as food, distribution, eating out, health care, nursing, nursing care, and accommodation.

Claims

1. A laminated film having (A) a seal layer, (B) a core layer, and (C) a laminate layer, (A) the sealing layer contains polypropylene and an ethylene-propylene copolymer; (B) the core layer and (C) the laminate layer each contain linear low-density polyethylene; (A) The above laminate film, wherein the content of the above ethylene-propylene copolymer in the seal layer is 35 to 70 mass %.

2. The density of the ethylene-propylene copolymer is 850 to 900 kg / m ３ The laminated film according to claim 1, wherein

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

4. The laminated film according to claim 1 or 2, which is used to seal polyethylene resin-coated paper containers.