Laminated film and laminate using the same

Abstract

To provide a laminated film containing a biomass plastic and improved in heat sealability (heat seal strength), and a laminate formed from the laminated film.SOLUTION: The laminated film comprises at least a layer (a) and a heat seal layer (b), wherein (1) the laminated film contains a biomass plastic, and (2) the heat seal layer (b) contains a polyolefin PO1 having at least one melting peak temperature in the range of 60 °C to 145 °C. (3) The layer (a) contains the polyolefin resin-based PO1 and a polyolefin resin-based PO2 having at least one melting peak temperature at 155 °C or higher, and (4) the contents of the polyolefin resin-based PO1 and the polyolefin resin-based PO2 in the layer or the film satisfy specific conditions.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated film and a laminate using the same. [Background technology]

[0002] Resin films are highly valuable functional materials that are widely used in a variety of applications, such as packaging materials for food and medicine, protective films for displays, etc., due to their excellent properties such as moisture resistance, water resistance, and oil resistance, as well as good mechanical strength.

[0003] On the other hand, in recent years, various problems have been raised, such as the increase in the amount of discarded plastic materials and concerns about global warming caused by carbon dioxide generated during the incineration of plastic materials. For this reason, biodegradable biomass plastics have attracted much attention from the perspective of consideration for the global environment and the human body, and the development of various materials that combine conventional plastic materials with biomass plastics has been actively pursued (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 23758 [Patent Document 2] Special Publication No. 2017-519863 Summary of the Invention [Problem to be solved by the invention]

[0005] However, films that combine thermoplastic resins, particularly crystalline thermoplastic resins, with biomass plastics have insufficient heat sealability (heat seal strength) due to the inclusion of biomass plastics, and therefore the uses of films that blend crystalline thermoplastic resins with biomass plastics have sometimes been limited.

[0006] The present invention has been made in view of the above, and aims to provide a laminated film containing biomass plastics, which has improved heat sealing properties (heat sealing strength), and a laminate formed from the laminated film. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above object, the present inventors have found that a laminated film that has been subjected to a specific treatment can achieve the above object, and have thus completed the present invention.

[0008] That is, the present invention includes, for example, the subject matter described in the following sections. 1. A laminated film comprising at least a layer a and a heat-sealable layer b, (1) The laminated film contains biomass plastic, (2) The heat seal layer b contains a polyolefin resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower, (3) The layer a contains the polyolefin resin PO1 and a polyolefin resin PO2 having at least one melting peak temperature of 155°C or higher, (4) A laminated film, wherein the polyolefin resin PO1 and the polyolefin resin PO2 satisfy at least one of the following conditions (I) to (IV): (I) The content PO1 of the polyolefin resin PO1 in the layer a a is 6% by mass or more, (II) Content PO1 of the polyolefin resin PO1 in the laminated film F is 15% by mass or more, (III) The content PO2 of the polyolefin resin PO2 in the layer a a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a ] is 0.09 or more, (IV) The content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to F Mass ratio of [PO1 F / PO2 F ] is 0.23 or higher. 2. The laminated film according to item 1, wherein the layer a and the heat-sealable layer b are directly laminated together. 3. The laminated film according to item 1 or 2, which has a heat seal strength of 5 N / 25 mm or more at 120°C. 4. The laminate film is biaxially stretched, and further characterized in that the polyolefin resin PO1 and the polyolefin resin PO2 satisfy at least one of the following conditions (V) to (VIII): (V) The content PO2 of the polyolefin resin PO2 in the layer a a is 45% by mass or more, (VI) The content PO2 of the polyolefin resin PO2 in the laminated film F is 48% by mass or more, (VII) The content PO2 of the polyolefin resin PO2 in the layer a a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a ] is 0.6 or less, (VIII) The content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to F Mass ratio of [PO1 F / PO2 F ] is less than 0.7. 5. A laminate comprising the laminate film according to any one of items 1 to 4 above and a substrate. [Effects of the Invention]

[0009] The laminated film of the present invention has good heat sealability (heat seal strength) despite being a laminated film containing biomass plastic. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "consist essentially of," and "consist only of."

[0011] The laminated film of the present invention is a laminated film comprising at least a layer a and a heat-sealable layer b, (1) The laminated film contains biomass plastic, (2) The heat seal layer b contains a polyolefin resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower, (3) The layer a contains the polyolefin resin PO1 and a polyolefin resin PO2 having at least one melting peak temperature of 155°C or higher, (4) The polyolefin-based resin PO1 and the polyolefin-based resin PO2 satisfy at least one of the following conditions (I) to (IV): (I) The content PO1 of the polyolefin resin PO1 in the layer a a is 6% by mass or more, (II) Content PO1 of the polyolefin resin PO1 in the laminated film F is 15% by mass or more, (III) The content PO2 of the polyolefin resin PO2 in the layer a a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a ] is 0.09 or more, (IV) The content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to FMass ratio of [PO1 F / PO2 F ] is 0.23 or higher.

[0012] The laminate film of the present invention having the above characteristics has good heat sealability (heat seal strength) despite being a laminate film containing biomass plastic. Specifically, the heat seal strength at 120°C is 4 N / 25 mm or more, preferably 5 N / 25 mm or more. The laminate film of the present invention may be either stretched or unstretched, but is preferably biaxially stretched from the viewpoint of providing the laminate film with excellent tensile modulus (stiffness) in addition to excellent heat sealability.

[0013] layer a The laminate film of the present invention comprises at least layer a and heat seal layer b. In the laminate film of the present invention, the layer containing the biomass plastic is not limited, but when layer a is used as the core layer of the laminate film, it is preferable that the biomass plastic be contained in layer a. Below, an embodiment in which layer a is used as the core layer of the laminate film and layer a contains the biomass plastic will be described as an example. In addition, when the laminate film of the present invention has a three-layer structure, layer a will also be referred to as the middle layer in the following description.

[0014] Layer a typically contains not only bioplastics but also a resin, such as a polyolefin resin, that is partially substituted with the bioplastic. That is, a conventionally known resin as the main component, in this case a polyolefin resin, is partially substituted with a biodegradable bioplastic from the viewpoint of consideration for the global environment and human health.

[0015] (Crystalline thermoplastic resin A) The crystalline thermoplastic resin A is a polyolefin resin that serves as the main component of the layer a. As the crystalline thermoplastic resin A, it is preferable to use a crystalline polyolefin resin having a melting point of approximately 150°C to 175°C. The laminated film of the present invention must contain, in the layer a, a polyolefin resin PO2 that has at least one melting peak temperature of 155°C or higher, and the content of PO2 must satisfy the specific conditions described below.

[0016] As used herein, a crystalline thermoplastic resin refers to a thermoplastic resin that exhibits a clear melting peak in the DSC curve measured using a differential scanning calorimeter (e.g., a Perkin-Elmer Diamond DSC, power-compensated DSC) under a nitrogen flow, when heated from -40°C to 300°C at a rate of 20°C / min, held at 300°C for 5 minutes, cooled to -40°C at 20°C / min, held at -40°C for 5 minutes, and then heated again to 300°C at 20°C / min. On the other hand, an amorphous thermoplastic resin refers to a thermoplastic resin that does not exhibit a clear melting peak in the above measurement using DSC.

[0017] Examples of the crystalline thermoplastic resin A include a wide variety of known crystalline polyolefin-based resins. Examples of the crystalline polyolefin-based resin include polymers obtained by polymerizing olefins, preferably those having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specific examples of the crystalline polyolefin-based resin include crystalline polyethylene resins, polypropylene resins, poly(1-butene) resins, polyisobutene resins, poly(1-pentene) resins, and poly(4-methylpentene-1) resins. The crystalline polyolefin-based resin is preferably a crystalline polypropylene-based resin, since it is easily mixed (compatible) with the biomass plastics. The crystalline polyolefin-based resin may be a single resin or a mixture of two or more resins.

[0018] When the crystalline thermoplastic resin A is a crystalline polypropylene-based resin, the crystalline polypropylene-based resin is more preferably at least one selected from the group consisting of a propylene homopolymer and a propylene-ethylene copolymer. When the crystalline polyolefin-based resin is a crystalline propylene homopolymer, the mechanical strength and heat resistance of the film are likely to be improved, and when the crystalline polyolefin-based resin is a crystalline propylene-ethylene copolymer, the film is likely to have improved fold crack resistance at low temperatures and low surface gloss.

[0019] Furthermore, when the crystalline polyolefin resin contains two components, a crystalline propylene homopolymer and a crystalline propylene-ethylene copolymer, a film with excellent heat resistance and low-temperature fold crack resistance is easily obtained. The mass ratio of the crystalline propylene homopolymer to the crystalline propylene-ethylene copolymer is preferably crystalline propylene homopolymer (P1):crystalline propylene-ethylene copolymer (P2) = 70:30 to 99:1, more preferably P1:P2 = 75:25 to 98:2, and even more preferably P1:P2 = 78:22 to 97:3.

[0020] The crystalline propylene homopolymer is preferably a crystalline isotactic polypropylene resin. Such a crystalline isotactic polypropylene resin preferably has a mesopentad fraction ([mmmm]), which is the degree of stereoregularity determined by high-temperature nuclear magnetic resonance (NMR) measurement, of 92% to 98%, more preferably 93% to 97%. When the mesopentad fraction [mmmm] is 92% or more, the high stereoregularity improves the crystallinity of the resin, making it easier to achieve high thermal stability and mechanical strength. On the other hand, when the mesopentad fraction [mmmm] is 98% or less, good stretchability is likely to be achieved. As a precaution, good stretchability means that, in the case where the laminate film is a stretched film, the material (raw sheet) for forming the stretched film is easily stretched, so that the resulting stretched film can be in a sufficiently stretched state (the same applies hereinafter when referring to "stretching" or "stretchability").

[0021] There are no particular limitations on the high-temperature NMR device that can be used to measure the mesopentad fraction ([mmmm]). For example, a commercially available high-temperature nuclear magnetic resonance (NMR) device capable of measuring the stereoregularity of polyolefins can be used. An example of such a device is the JNM-ECP500 high-temperature Fourier transform nuclear magnetic resonance device (high-temperature FT-NMR) manufactured by JEOL Ltd. 13 The measurement temperature was 135°C (125 MHz), and the solvent used was ortho-dichlorobenzene (ODCB: a mixed solvent of ODCB and deuterated ODCB (volume ratio = 4 / 1)). High-temperature NMR can be performed using known methods, such as those described in "New Edition Polymer Analysis Handbook, edited by the Japan Analytical Chemistry and Polymer Analysis Research Forum, Kinokuniya Shoten, 1995, p. 610." The measurement mode was single pulse proton broadband decoupling, pulse width 9.1 μsec (45° pulse), pulse interval 5.5 sec, number of accumulations 4500, and shift reference CH3 (mmmm) = 21.7 ppm.

[0022] The pentad fraction, which indicates the degree of stereoregularity, is calculated as a percentage from the integrated intensity of each signal derived from a combination of five pentads (pentads) consisting of meso (m) pentads arranged in the same direction and racemo (r) pentads arranged in the opposite direction (e.g., mmmm, mrrm, etc.). For the assignment of signals derived from mmmm, mrrm, etc., see, for example, the spectral descriptions in T. Hayashi et al., Polymer, Vol. 29, p. 138 (1988). The meso pentad fraction ([mmmm]) can be controlled by appropriately adjusting the polymerization conditions of the polypropylene resin, the type of catalyst, the amount of catalyst, and other polymerization conditions.

[0023] The crystalline thermoplastic resin A preferably has a melting point of 150°C to 175°C. When the melting point of the crystalline thermoplastic resin A is within the above range, the heat resistance, productivity, and stretchability of the resulting stretched film are easily maintained at a good level. In addition, the resin is easily mixed (miscible) uniformly with biomass plastics, and the stretch ratio is easily adjusted. The melting point of the crystalline thermoplastic resin A is preferably 150°C to 170°C, more preferably 155°C to 166°C, even more preferably 155°C to 164°C, and particularly preferably 155°C to 163°C.

[0024] The glass transition temperature of the crystalline thermoplastic resin A is not particularly limited, and can be, for example, 50°C or lower, more preferably -30°C to 30°C.

[0025] In the present invention, the melting point and glass transition temperature of the crystalline resin A are values ​​measured using a differential scanning calorimeter (for example, a power compensation type DSC, Diamond DSC manufactured by Perkin-Elmer).

[0026] The melt mass flow rate of the crystalline thermoplastic resin A is not particularly limited. The melt mass flow rate of the crystalline thermoplastic resin A is preferably 0.5 g / 10 min to 8 g / 10 min, more preferably 1 g / 10 min to 6 g / 10 min, in order to ensure that the fluidity of the resin is within an appropriate range, and the size of the finely dispersed particles is easily controlled, making it easy to produce a desired stretched film. The melt mass flow rate referred to in this specification refers to a value measured at 230°C and 21.18 N in accordance with JIS K-7210 (1999).

[0027] The crystalline thermoplastic resin A can be produced by a known method. For example, when the crystalline thermoplastic resin A is a crystalline propylene homopolymer, it can be produced by a method of polymerizing propylene in a hydrocarbon solvent using a Ziegler catalyst system consisting of a titanium and aluminum compound, a method of polymerizing in liquid propylene (bulk polymerization), a method of polymerizing in a gas phase, or the like. The crystalline propylene homopolymer can be obtained commercially, and representative commercially available products include homopolymers from the Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., PC412A manufactured by SunAllomer Co., Ltd., homopolymers from the Novatec (registered trademark) series manufactured by Japan Polypropylene Corporation, the Daploy series manufactured by Borealis, the 5014L series manufactured by Taihan Yuhka Industrial Co., Ltd., and homopolymers from the Sumitomo Noblen (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd.

[0028] When the crystalline thermoplastic resin A is a crystalline propylene-ethylene copolymer, it may be either a random copolymer of propylene and ethylene or a block copolymer of propylene and ethylene. The ethylene unit content in the crystalline propylene-ethylene copolymer may be 50% by mass or less. The crystalline propylene-ethylene copolymer can be produced by a known method or can be obtained as a commercially available product. Representative commercially available products include copolymers from the Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., copolymers from the Novatec PP (registered trademark) series and the Wintec (registered trademark) series manufactured by Japan Polypropylene Corporation, and copolymers from the Sumitomo Noblen (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd.

[0029] (Biomass Plastic B) The biomass plastic B in the present invention (hereinafter also simply referred to as "biomass plastic") is not limited to a specific type as long as it is biodegradable, and examples thereof include a wide range of known biomass plastics. Specific examples include biodegradable aliphatic polyester resins.

[0030] Examples of biodegradable aliphatic polyester resins include aliphatic polyester resins such as polylactic acid, polyhydroxyalkanoic acid (excluding polylactic acid), polyhydroxybutyrate, polycaprolactone, polybutylene succinate, polybutylene succinate / adipate, polyethylene succinate, polymalic acid, polyglycolic acid, polydioxanone, and poly(2-oxetanone). Examples of natural polymers include starch, cellulose, chitin, chitosan, gluten, gelatin, zein, soy protein, collagen, and keratin. Biomass plastics can be used alone or in combination of two or more types.

[0031] The biomass plastic is preferably an aliphatic polyester resin, since it is easily mixed uniformly with the crystalline thermoplastic resin A, which is the main resin of layer a, and a stretched film can be easily obtained. Of these, one or more types selected from the group consisting of polylactic acid, polyhydroxyalkanoic acid, and polymers of mixed monomers containing lactic acid and polyhydroxyalkanoic acid are more preferable.

[0032] As the polylactic acid, a wide variety of known polylactic acids can be used, such as polylactic acid obtained by condensation polymerization of lactic acid components as raw material monomers. Polylactic acid can contain either the optical isomers L-lactic acid (L-form) or D-lactic acid (D-form), or both. When polylactic acid is composed mainly of L-lactic acid (L-form), the content of the D-form is preferably 5.0 mol% or less, more preferably 3.0 mol% or less, even more preferably 1.0 mol% or less, and particularly preferably 0.01 mol% or less. When polylactic acid is composed mainly of D-lactic acid (D-form), the content of the L-form is preferably 5.0 mol% or less, more preferably 3.0 mol% or less, even more preferably 1.0 mol% or less, and particularly preferably 0.01 mol% or less. The glass transition temperature, crystallization temperature, molecular weight, etc. of the polylactic acid are not particularly limited.

[0033] Examples of polyhydroxyalkanoic acids include polymers of hydroxycarboxylic acid components containing at least one of hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, and glycolic acid.

[0034] Examples of the polymer of a mixed monomer containing lactic acid and polyhydroxyalkanoic acid include a polymer obtained by polycondensing a lactic acid monomer with the hydroxycarboxylic acid component.

[0035] The biomass plastic preferably has a melting point of 110°C to 200°C. When the melting point of the biomass plastic is within the above range, it is easy to maintain good heat resistance and productivity of the resulting laminated film. In addition, it is easy to mix (be compatible) uniformly with the crystalline thermoplastic resin A, which is the main resin of layer a, and it is easy to adjust the stretch ratio. The melting point of the biomass plastic is preferably 120°C to 190°C, more preferably 130°C to 185°C, and even more preferably 140°C to 180°C.

[0036] The glass transition temperature of the biomass plastic is not particularly limited and can be, for example, from -40°C to 70°C, and more preferably from 0°C to 70°C.

[0037] In the present invention, the melting point and glass transition temperature of the biomass plastic are values ​​measured using a differential scanning calorimeter (for example, a power compensation type DSC, Diamond DSC manufactured by Perkin-Elmer).

[0038] The melt mass flow rate of the biomass plastic is not particularly limited. The melt mass flow rate of the biomass plastic is preferably 0.5 g / 10 min to 15 g / 10 min, more preferably 1 g / 10 min to 10 g / 10 min, and even more preferably 2 g / 10 min to 10 g / 10 min, in order to ensure that the resin has an appropriate fluidity range and that the size of the finely dispersed particles is easily controlled, facilitating the production of a desired laminated film. The melt mass flow rate referred to in this specification refers to a value measured at 230°C and 21.18 N in accordance with JIS K-7210 (1999).

[0039] The method for producing biomass plastics is not particularly limited, and for example, a wide variety of known methods for producing biomass plastics can be employed. Biomass plastics can also be obtained commercially. Representative commercially available polylactic acid products include "4032D" (melting point 163°C) manufactured by NatureWorks, and "L175" (melting point 175°C), "LX175" (melting point 155°C), and "LX930" (melting point 130°C) manufactured by Total Corbion PLA. Other representative commercially available biomass plastic products include polyhydroxyalkanoate "ENMAT (registered trademark) Y1000P" manufactured by Tianan Biologic Material, and polybutylene succinate "BioPBS (registered trademark) FZ91" and "BioPBS (registered trademark) FD82" manufactured by Mitsubishi Chemical Corporation.

[0040] (Thermoplastic resin C; Compatibilizer) Thermoplastic resin C is an optional component contained in the resin component of layer a, and is a component that can function as, for example, a compatibilizer to enhance the compatibility between crystalline thermoplastic resin A and biomass plastic (biomass plastic B).

[0041] The thermoplastic resin C may be, for example, a thermoplastic resin having a glass transition temperature of -60°C to 90°C (preferably -60°C to 10°C). When the glass transition temperature of the thermoplastic resin C is within the above range, the compatibility of the crystalline thermoplastic resin A and the biomass plastic is easily improved, and the thermoplastic resin C present at the interface between them tends to increase the stretchability of the film. This is because, in order to obtain excellent stretchability, it is necessary for molecular motion to be unconstrained, and therefore a glass transition temperature significantly lower than the stretching temperature is required.

[0042] The glass transition temperature of the thermoplastic resin C is more preferably −55° C. to 0° C. In the present invention, the glass transition temperature of the thermoplastic resin C is a value measured using a differential scanning calorimeter (for example, a power compensation DSC, Diamond DSC manufactured by Perkin-Elmer).

[0043] The thermoplastic resin C may be either crystalline or amorphous, but is preferably amorphous in that it can further enhance the compatibility between the crystalline thermoplastic resin A and the biomass plastic. In other words, it is preferable that the thermoplastic resin C has a melting point that cannot be detected by a differential scanning calorimeter.

[0044] Specific examples of the thermoplastic resin C include thermoplastic elastomers, including a wide range of known thermoplastic elastomers having a glass transition temperature of -60°C to 90°C (preferably -60°C to 10°C). The thermoplastic resin C is preferably a random copolymer, block copolymer, or graft copolymer formed of two or more segments that have good affinity with the crystalline thermoplastic resin A and the biomass plastic. This tends to increase the compatibility between the crystalline thermoplastic resin A and the biomass plastic, making it easier to improve the transparency of the film. Specific examples of the thermoplastic elastomer include styrene-grafted polyethylene, hydrogenated styrene-butadiene block copolymer (hereinafter referred to as "SEBS"), and a graft compound of ethylene-glycidyl methacrylate copolymer and acrylonitrile-styrene copolymer (hereinafter referred to as "EGMA-g-AS").

[0045] The melt flow rate of thermoplastic resin C is not particularly limited, and is preferably equal to or higher than the melt flow rates of crystalline thermoplastic resin A and biomass plastic, for example, in order to facilitate mixing with both.

[0046] The method for producing the thermoplastic resin C is not particularly limited, and for example, a wide variety of methods for producing known thermoplastic elastomers can be used. The thermoplastic resin C can also be obtained from commercially available products. Representative commercially available products of the thermoplastic resin C include, for example, hydrogenated SBR "Dynaron" manufactured by JSR Corporation, "Tuftec" manufactured by Asahi Kasei Corporation, "Septon" manufactured by Kuraray Co., Ltd., and "Modiper A1100," "Modiper A1401," "Modiper A3400," and "Modiper A5400" manufactured by NOF Corporation.

[0047] (Thermoplastic resin D) Thermoplastic resin D is an essential component contained in the resin component of layer a, and is a component that can play a role in, for example, improving the heat sealability (heat seal strength) of the laminated film of the present invention. Note that the laminated film of the present invention must contain, in layer a, a polyolefin resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower, and the content of PO1 must satisfy the specific conditions described below.

[0048] Examples of thermoplastic resin D include thermoplastic resins having a melting point of less than 150° C., particularly a melting point of 60° C. to 145° C. Specific examples include crystalline propylene-α-olefin random copolymers, where the α-olefins include ethylene and α-olefins having 4 to 20 carbon atoms, and preferably ethylene, butene-1, hexene-1, octene-1, etc., and more preferably copolymers or terpolymers using ethylene or butylene, and particularly preferably ethylene-propylene-1-butene copolymers (5C37F manufactured by SunAllomer Co., Ltd., melting point 132° C.), propylene-ethylene-butene random copolymers (FL6741G manufactured by Sumitomo Chemical Co., Ltd., melting point 130° C.), propylene-1-butene copolymers (Tafmer XM7070S manufactured by Mitsui Chemicals, Inc., melting point 75° C.), etc.

[0049] (Content of each component in layer a) Layer a preferably contains 30 to 96 mass% of crystalline thermoplastic resin A relative to the total mass of crystalline thermoplastic resin A and biomass plastic (biomass plastic B), which improves the compatibility between crystalline thermoplastic resin A and biomass plastic, making it easier to obtain a stretched film with the desired stretch ratio.

[0050] The content of crystalline thermoplastic resin A is more preferably 50 to 90% by mass based on the total mass of crystalline thermoplastic resin A and biomass plastic. The biomass content in the laminated film of the present invention is not limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, with the upper limit being approximately 30% by mass.

[0051] The crystalline thermoplastic resin A and the biomass plastic contained in layer a can each be any of the various resins described above, and any combination can be used. In particular, it is preferable that the absolute value of the difference between the melting points of the crystalline thermoplastic resin A and the biomass plastic is 0 to 50°C. In this case, the crystalline thermoplastic resin A and the biomass plastic are mixed more uniformly (i.e., the compatibility between them is increased), making it easier to adjust the stretch ratio. The difference between the melting points of the crystalline thermoplastic resin A and the biomass plastic is more preferably 0 to 40°C, even more preferably 0 to 30°C, and even more preferably 0 to 20°C.

[0052] In another embodiment, a preferred combination of crystalline thermoplastic resin A and biomass plastic is one in which the glass transition temperature of the crystalline thermoplastic resin A contained in layer a is 50°C or lower, and the glass transition temperature of the biomass plastic is -40°C to 70°C. In this case, the crystalline thermoplastic resin A and the biomass plastic are mixed more uniformly (i.e., the compatibility between them is increased), making it easier to adjust the stretch ratio. In this combination, the glass transition temperature of the crystalline thermoplastic resin A is more preferably -30°C to 30°C. In this combination, the glass transition temperature of the biomass plastic is more preferably 0°C to 60°C.

[0053] A combination in which the glass transition temperatures of the crystalline thermoplastic resin A and the biomass plastic contained in the layer a are within the above range and the difference in melting point between them is within the above range is particularly preferred.

[0054] The resin components forming layer a may further contain thermoplastic resin C as a compatibilizer. When layer a contains thermoplastic resin C, layer a preferably contains 96 to 50 mass% of crystalline thermoplastic resin A, 3 to 30 mass% of biomass plastic, and 1 to 20 mass% of thermoplastic resin C, based on the total mass of the resin components. In this case, the crystalline thermoplastic resin A and the biomass plastic are mixed particularly uniformly (i.e., the compatibility between the two is particularly high), making it particularly easy to adjust the draw ratio.

[0055] The resin component forming Layer a further contains Thermoplastic Resin D to enhance heat sealability. Layer a preferably contains 96 to 30 mass% of crystalline thermoplastic resin A, 3 to 60 mass% of biomass plastic, and 6 to 35 mass% of thermoplastic resin D, based on the total mass of the resin component. This enhances the heat sealability (heat seal strength) of the laminated film of the present invention.

[0056] In layer a, the content of crystalline thermoplastic resin A is preferably 95 to 40 mass%, and more preferably 90 to 50 mass%, based on the total mass of the resin components. In layer a, the content of biomass plastic is preferably 4 to 25 mass%, and more preferably 9 to 20 mass%, based on the total mass of the resin components. In layer a, the content of thermoplastic resin C can be appropriately set depending on the content of crystalline thermoplastic resin A and biomass plastic. For example, the content of thermoplastic resin C is more preferably 1 to 15 mass%, and particularly preferably 1 to 10 mass%, based on the total mass of the resin components. In layer a, the content of thermoplastic resin D can be appropriately set depending on the content of crystalline thermoplastic resin A and biomass plastic. For example, the content of thermoplastic resin D is more preferably 7 to 35 mass%, and particularly preferably 7.5 to 30 mass%, based on the total mass of the resin components.

[0057] The resin components constituting layer a may consist solely of crystalline thermoplastic resin A, biomass plastic, thermoplastic resin C, and thermoplastic resin D. However, this does not exclude components that are inevitably contained in the resin components. Furthermore, as long as the effects of the present invention are not impaired, the resin components constituting layer a may contain resins other than crystalline thermoplastic resin A, biomass plastic, thermoplastic resin C, and thermoplastic resin D. However, the content of the other resins is preferably 15% by mass or less, and more preferably 10% by mass or less, based on the total mass of the resin components contained in layer a. The lower limit of the content of the other resins is not particularly limited, and may be, for example, 0% by mass or 1% by mass.

[0058] Heat seal layer b The laminate film of the present invention is a multilayer laminate film having at least layer a (core layer) and heat seal layer b. This can improve the heat sealability of the laminate film. Here, heat sealability means that the heat seal layers b have the property of fusing together when they are placed face to face and thermocompressed together.

[0059] The type of heat seal layer b is not particularly limited, and for example, a wide range of known heat seal layers used in laminate films can be used. The heat seal layer b can be formed from, for example, various resins (however, resins other than crystalline thermoplastic resin A and crystalline polyolefin resin F described below).

[0060] (Resin E used in heat seal layer b) For example, resin E used in the heat-seal layer can be a thermoplastic resin having a melting point of less than 150°C, similar to thermoplastic resin D, and a wide variety of resins for forming known heat-seal layers can be used as long as the resin is of this type. In particular, resins used in the heat-seal layer include crystalline propylene-α-olefin random copolymers, and the α-olefins include ethylene and α-olefins having 4 to 20 carbon atoms. Ethylene, butene-1, hexene-1, octene-1, and the like are preferred, and copolymers or terpolymers using ethylene or butylene are more preferred. An ethylene-propylene-1-butene copolymer (5C37F manufactured by SunAllomer Co., Ltd., melting point 132°C), a propylene-ethylene-butene random copolymer (FL6741G manufactured by Sumitomo Chemical Co., Ltd., melting point 130°C), and a propylene-1-butene copolymer (Tafmer XM7070S manufactured by Mitsui Chemicals, Inc., melting point 75°C) are particularly preferred. The heat-sealable layer may contain an anti-blocking agent such as acrylic resin fine particles or silica within a range that does not impair the effects of the present invention. Note that the laminated film of the present invention requires that the heat-sealable layer (b) contains a polyolefin resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower, and the content of PO1 must satisfy the specific conditions described below.

[0061] The heat-sealable layer b may be laminated by being directly attached to the layer a, or another layer may be interposed between the layer a and the heat-sealable layer b. When the heat-sealable layers b are formed on both sides of the layer a, the heat-sealable layers b may be formed of the same components, or may be formed of different components.

[0062] The method for forming the layer a and the method for laminating the heat-sealable layer b will be explained later in the section on the method for producing the laminated film.

[0063] Layers other than layer a and heat seal layer b The laminated film of the present invention may also include layers (other layers) other than the layer a and the heat-sealable layer b. An example of such other layer is a skin layer c formed of a resin. An example of the resin contained in the skin layer c is a crystalline polyolefin resin F having a melting point of 150 to 175°C.

[0064] That is, one embodiment of the laminate film of the present invention includes an embodiment in which a skin layer c is provided on one side of the layer a, and the skin layer c contains a crystalline polyolefin resin F having a melting point of 150 to 175° C. When the skin layer c is provided, for example, the laminate film can be made more smooth.

[0065] (Crystalline polyolefin resin F) The crystalline polyolefin resin F having a melting point of 150 to 175°C is, for example, a polymer obtained by polymerizing an olefin, similar to the crystalline thermoplastic resin A, and preferably includes a polymer obtained by polymerizing an olefin having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specific examples of the crystalline polyolefin resin F include crystalline polyethylene resin, polypropylene resin, poly(1-butene) resin, polyisobutene resin, poly(1-pentene) resin, and poly(4-methylpentene-1) resin, as well as copolymers of α-olefins such as ethylene-propylene copolymer, propylene-butene copolymer, ethylene-butene copolymer, and propylene-ethylene-butene copolymer. The crystalline polyolefin resin F can be a single type or a mixture of two or more types. The crystalline polyolefin resin F contained in the skin layer c may be the same as the crystalline thermoplastic resin A contained in the layer a.

[0066] The skin layer c may be laminated by being directly bonded to the layer a, or another layer may be interposed between the layer a and the skin layer c. From the viewpoint of reducing the haze of the laminate film of the present invention, it is preferable that the skin layer c is laminated by being directly bonded to the layer a.

[0067] The laminate film of the present invention may further include a layer d other than the heat seal layer b and the skin layer c, as long as the effects of the present invention are not impaired. Examples of layer d include a layer having one or more functions such as antifogging properties, antistatic properties, adhesive properties, non-adhesive properties, smoothness, gloss, printability, blocking resistance, slip properties, strength-imparting properties, flexibility-imparting properties, gas barrier properties against oxygen gas, ethylene gas, etc., water vapor barrier properties, odor component barrier properties, prevention of component migration of package contents, antibacterial properties, antifungal properties, and the like, and a layer having one or more of these functions and heat sealability.

[0068] Layer d may be laminated by being directly attached to layer a, or another layer (for example, the skin layer c) may be interposed between layer a and layer d. When layers d are formed on both sides of layer a, the layers d may be formed of the same component or different components.

[0069] As described above, the laminate film of the present invention can include a laminate in which the layer a serves as a core layer and the heat-seal layer b is directly bonded to one or both sides of the core layer (i.e., b / a / b). The laminate film of the present invention can also include a laminate in which the layer a serves as a core layer and the heat-seal layer b is directly bonded to one side of the core layer and the skin layer c or layer d is bonded to the opposite side (i.e., b / a / c or b / a / d).

[0070] The laminated film of the present invention is preferably a laminated film in which the layer a is used as a core layer, the heat seal layer b is directly laminated to one surface of the core layer, and the skin layer c is directly laminated to the other surface.

[0071] (Optional Additives) The laminate film of the present invention may contain additives as optional components, if necessary. Examples of the additives include a wide range of known additives that are used in laminate films, such as heat stabilizers, antioxidants, organic and inorganic lubricants, chlorine scavengers, antistatic agents, antifogging agents, and hydrolysis inhibitors.

[0072] Examples of the heat stabilizer and antioxidant include phenol-based, hindered amine-based, phosphite-based, lactone-based, and tocopherol-based heat stabilizers and antioxidants. Specific examples include dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ("Irganox® 1010" manufactured by BASF Japan Ltd.), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4hydroxy)benzene ("Irganox® 1330" manufactured by BASF Japan Ltd.), and tris(2,4-di-t-butylphenyl)phosphite ("Irgafos® 168" manufactured by BASF Japan Ltd.). Among these, at least one selected from phenol-based antioxidants or a combination thereof, a combination of a phenol-based antioxidant and a phosphite-based antioxidant, a combination of a phenol-based antioxidant and a lactone-based antioxidant, or a combination of a phenol-based antioxidant, a phosphite-based antioxidant and a lactone-based antioxidant are preferred from the viewpoint of imparting chemical stability to the film.

[0073] Examples of lubricants include organic lubricants such as aliphatic amides such as stearic acid amide and erucic acid amide, lauric acid diethanolamide, alkyldiethanolamine, aliphatic monoglycerides, aliphatic diglycerides, and silicone crosslinked polymers, and inorganic lubricants such as silica and alumina, but organic lubricants are preferred because they cause less staining on printing plates in printing applications.

[0074] Examples of chlorine scavengers include calcium stearate, metal soaps, and hydrotalcite.

[0075] Examples of antistatic agents include alkylmethyl dibetaine, alkylamine diethanol and / or alkylamine ethanol ester and / or alkylamine diethanol diester. Two or more of these antistatic agents may be used in combination, and an aliphatic alcohol may also be used in combination. Among these, the combined use of stearyl diethanolamine monostearate and stearyl diethanolamine is preferred because it provides excellent antistatic performance and improves printability. Representative examples of commercially available antistatic agents include the Electrostripper (registered trademark) series manufactured by Kao Corporation.

[0076] The type of antifogging agent is not particularly limited, and examples thereof include a wide range of antifogging agents used in general polyolefin films, such as esters of polyhydric alcohols (e.g., glycerin, polyethylene glycol, pentaerythritol, sorbitol, polypropylene glycol) with higher fatty acids (e.g., lauric acid, stearic acid, oleic acid), ethylene oxide adducts of higher aliphatic amines, higher aliphatic alkanolamides, higher alcohol phosphate ester salts, and mixtures thereof.

[0077] The type of hydrolysis stabilizer inhibitor is not particularly limited, and examples thereof include a wide range of compounds that have the function of preventing or inhibiting hydrolysis. Examples of suitable hydrolysis stabilizers include at least one conventionally known hydrolysis stabilizer selected from carbodiimide compounds, epoxy compounds, and the like. Here, a carbodiimide compound refers to one or more carbodiimides in the molecule. The hydrolysis inhibitor of the present invention preferably has a functional group reactive with the hydroxyl and / or carboxyl groups of the crystalline thermoplastic resin B described above. Examples of such functional groups include epoxy groups, carbodiimide groups, amino groups, isocyanate groups, oxazoline groups, carboxylic anhydride groups, and phthalic anhydride. Among these, carbodiimide groups are preferred due to their high reactivity with the hydroxyl and / or carboxyl groups that constitute part of the aliphatic polyester resin. It is therefore preferred to use a carbodiimide compound having one or more carbodiimide groups in the molecule as the hydrolysis inhibitor.

[0078] Specific examples of the carbodiimide compound include isopropylcarbodiimide, dicyclohexylcarbodiimide, and dioctylcarbodiimide as carbodiimide compounds having one carbodiimide group in the molecule, and 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,4-cyclohexane diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate as carbodiimide compounds having two or more carbodiimide groups in the molecule. From the viewpoint of exhibiting good hydrolysis inhibitory properties, it is preferable to use a carbodiimide compound having two or more carbodiimide groups in the molecule as the hydrolysis inhibitor.

[0079] The additive may be contained in layer a, or a layer other than layer a (such as heat seal layer b, skin layer c, or layer d) may contain the additive. The content of the additive can be adjusted as desired to the extent that the effects of the present invention are not impaired, and can be, for example, 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less, based on the total mass of the laminate film.

[0080] The thickness of the laminated film of the present invention is not particularly limited and can be appropriately set depending on the intended use. The thickness of the laminated film is, for example, preferably 10 to 150 μm, more preferably 15 to 100 μm, and even more preferably 20 to 60 μm. The method for measuring the film thickness in this specification is the same as the method described in the Examples.

[0081] The laminated film of the present invention can be suitably used for welding seal bags, packaging, food packaging, medicine packaging, decorations (including fashion), labels, tape substrates, printing substrates, stationery, home appliances, poster paper, thermal paper substrates, recording paper substrates, interior and exterior use of homes, automobiles, containers, etc.

[0082] Laminated Film Embodiments and Preferred Embodiments The laminated film of the present invention contains, in addition to biomass plastic, a polyolefin-based resin, and the polyolefin-based resins include a polyolefin-based resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower, and a polyolefin-based resin PO2 having at least one melting peak temperature of 155°C or higher.

[0083] Examples of the polyolefin resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower include thermoplastic resin D, which is an essential component of the resin components of layer a, and resin E (which may be the same as thermoplastic resin D) forming the heat seal layer. Specifically, the polyolefin resin PO1 is preferably a crystalline propylene-α-olefin random copolymer, particularly a crystalline random polypropylene resin.

[0084] Examples of the polyolefin resin PO2 having at least one melting peak temperature of 155°C or higher include a crystalline thermoplastic resin A contained in the resin component of the layer a, and a crystalline polyolefin resin F (which may be the same as the crystalline thermoplastic resin A) that forms the skin layer b when a skin layer c is provided as a layer other than the layer a and the heat-seal layer b. Specifically, the polyolefin resin PO2 is preferably a crystalline homopolypropylene resin.

[0085] The polyolefin resin PO1 and the polyolefin resin PO2 must satisfy at least one of the following conditions (I) and (IV): (I) The content PO1 of the polyolefin resin PO1 in the layer a a is 6% by mass or more, (II) Content PO1 of the polyolefin resin PO1 in the laminated film F is 15% by mass or more, (III) The content PO2 of the polyolefin resin PO2 in the layer a a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a ] is 0.09 or more, (IV) The content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to F Mass ratio of [PO1 F / PO2 F ] is 0.23 or higher.

[0086] Regarding the condition (I), the content PO1 of the polyolefin resin PO1 in the layer a (core layer) a The content of the polyisocyanate may be 6% by mass or more, preferably 7 to 35% by mass, more preferably 7.5 to 30% by mass, and even more preferably 10 to 30% by mass. Within this range, the heat sealability of the laminated film of the present invention can be improved.

[0087] Regarding the condition (II), the content PO1 of the polyolefin resin PO1 in the laminated film F is sufficient as long as it is 15% by mass or more, but is preferably 16 to 40% by mass, more preferably 16 to 35% by mass, and even more preferably 18 to 34% by mass. If it is within this range, the heat sealability of the laminated film of the present invention can be improved.

[0088] Regarding the condition (III), the content PO2 of the polyolefin resin PO2 in the layer a (core layer) a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a ] is sufficient as long as it is 0.09 or more, but is preferably 0.1 to 0.8, more preferably 0.15 to 0.70, and even more preferably 0.16 to 0.68. Within such ranges, the heat sealability of the laminated film of the present invention can be improved.

[0089] Regarding the condition (IV), the content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to F Mass ratio of [PO1 F / PO2 F ] is sufficient as long as it is 0.23 or more, but is preferably 0.24 to 0.80, and more preferably 0.29 to 0.75. If it is within this range, the heat sealability of the laminated film of the present invention can be improved.

[0090] In a preferred embodiment, the laminate film of the present invention has layer a as an intermediate layer, and includes the intermediate layer, outer layer 1 laminated on one side of the intermediate layer, and outer layer 2 laminated on the other side of the intermediate layer, and it is preferred that outer layer 1 is heat-sealable layer b, outer layer 2 is skin layer c, and the laminate film is biaxially stretched. This embodiment preferably has a three-layer structure including layer a as an intermediate layer, and outer layer 1 and outer layer 2 directly in contact with the intermediate layer.

[0091] In the above embodiment, the polyolefin-based resin PO1 and the polyolefin-based resin PO2 preferably satisfy at least one of the following conditions (V) to (VIII): (V) The content PO2 of the polyolefin resin PO2 in the layer a a is 45% by mass or more, (VI) The content PO2 of the polyolefin resin PO2 in the laminated film F is 48% by mass or more, (VII) The content PO2 of the polyolefin resin PO2 in the layer a a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a ] is 0.6 or less, (VIII) The content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to F Mass ratio of [PO1 F / PO2 F ] is less than 0.7.

[0092] Regarding the condition (V), the content PO2 of the polyolefin resin PO2 in the layer a a The upper limit is preferably 85% by mass or less, and can be set to 82% by mass or less. Within this range, the tensile modulus (stiffness) of the laminated film of the present invention can be increased.

[0093] Regarding the condition (VI), the content PO2 of the polyolefin resin PO2 in the laminated film F The upper limit is preferably 80% by mass or less, and can be set to 76% by mass or less. Within this range, the tensile modulus (stiffness) of the laminated film of the present invention can be increased.

[0094] Regarding the condition (VII), the content PO2 of the polyolefin resin PO2 in the layer a a The content of the polyolefin resin PO1 relative to a Mass ratio of [PO1 a / PO2 a The lower limit of [value] is preferably 0.10 or more, and can be set to 0.11 or more. Within this range, the tensile modulus (stiffness) of the laminated film of the present invention can be increased.

[0095] Regarding the condition (VIII), the content PO2 of the polyolefin resin PO2 in the laminated film F The content of the polyolefin resin PO1 relative to F Mass ratio of [PO1 F / PO2 F The lower limit of [value] is preferably 0.20 or more, and can be set to 0.24 or more. Within this range, the tensile modulus (stiffness) of the laminated film of the present invention can be increased.

[0096] Laminated body using laminated film The laminate film of the present invention is preferably used as a laminate having the laminate film and a substrate, that is, the present invention also encompasses such a laminate.

[0097] The laminated film and the substrate can be bonded together by providing an adhesive layer or adhesive resin layer between them and using a known lamination process such as dry lamination or melt extrusion lamination, and optionally applying a surface treatment such as corona treatment.

[0098] Examples of substrates include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polyvinyl chloride resins, fluorine-based resins, poly(meth)acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as various nylons, polyimide resins, polyamideimide resins, polyarylphthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins, acetal resins, and cellulose resins, as well as various resin films or sheets and paper. Among these, polyethylene film and uniaxially oriented polypropylene (CPP) are preferred as substrates from the viewpoints of flexibility and heat sealability. It is preferred that the substrate contain biomass plastic.

[0099] Manufacturing method of laminated film The method for producing the laminate film of the present invention is not particularly limited, and for example, a wide variety of known production methods can be used. For example, the laminate film of the present invention can be produced by extruding a resin raw material containing at least a crystalline thermoplastic resin A and a biomass plastic B to obtain a resin sheet for layer a, and then performing a lamination step of at least a heat-sealing layer b to form a laminate sheet. When producing a biaxially stretched laminate film, it can be produced by stretching the laminate sheet. Hereinafter, such a production method, which optionally includes a stretching treatment, will be abbreviated as "Production Method A." The resin components constituting each layer and the types and contents of optional additives are as described above.

[0100] The resin raw material can be prepared by, for example, the same method as known preparation methods, such as a method of dry blending resin pellets or powder using a batch mixer such as a tumbler or mixer, or a continuous metering mixer; or a method of supplying resin pellets or powder, etc., together with other resin pellets or powder and / or additives as necessary, to a kneader and melt-kneading to obtain a melt-blend resin composition; etc. Among these, melt-kneading is preferred for preparing the resin raw material.

[0101] As the kneader used for melt kneading, a known kneader can be used, and it may be a single-screw type, a twin-screw type, or a multi-screw type with more than two screws. Furthermore, in the case of a twin-screw or more screw type, either a co-rotating or counter-rotating kneading type may be used. A co-rotating twin-screw kneader is preferred because it allows the crystalline thermoplastic resin A and the biomass plastic B to be mixed uniformly.

[0102] The melt-kneading temperature is preferably in the range of 200°C to 300°C, more preferably 220°C to 280°C. By setting the temperature within this range, the crystalline thermoplastic resin A and the biomass plastic B can be mixed more uniformly. To prevent deterioration of the resin during melt-kneading, an inert gas such as nitrogen can be purged. The melt-kneaded resin can be pelletized to an appropriate size using a commonly known granulator to obtain melt-blend resin composition pellets.

[0103] In production method A, a resin sheet can be obtained using the resin raw material obtained as described above. Specifically, the resin raw material is fed to an extruder, heated and melted, and, if necessary, fine foreign matter and the like is removed using a filter or the like, and then the melt is extruded into a sheet form through a T-die, thereby obtaining a resin sheet.

[0104] The extruder used to obtain the resin sheet can be, for example, a wide variety of known extruders. There are no limitations on the screw type of the extruder, and a single-screw type, twin-screw type, or multi-screw type with more than one screw may be used. When the resin raw materials are prepared by dry blending, using a twin-screw type or multi-screw type with more than one screw tends to provide excellent mixing and dispersion. The extrusion temperature is preferably in the range of 200°C to 300°C, more preferably 220°C to 280°C. To prevent thermal degradation of the resin during extrusion, an inert gas such as nitrogen can be purged.

[0105] The melt-extruded resin sheet is formed into a sheet by a known method, for example, by adhering it to at least one metal drum set at a temperature of 25 to 120°C using an air knife or other rolls, or by static electricity, etc., and the resin sheet is obtained as a so-called raw sheet. The temperature of the metal drum is more preferably 30 to 80°C.

[0106] The manufacturing method A further includes a lamination step of laminating at least a heat-sealable layer b on the layer a. In the lamination step, for example, a wide variety of conventional lamination methods can be used, including films obtained by laminating using a co-extrusion method, a lamination method, a heat-sealing method, etc.

[0107] Specifically, a resin sheet having a laminated structure can be obtained by co-extrusion of two or more dry-blended and / or melt-blended resin compositions (each resin composition may have the same or different composition). Alternatively, a laminated film can be produced by laminating a single-layer film with another film.

[0108] Examples of the coextrusion method include a pre-die lamination method in which molten resins are brought into contact in a feed block before a mold, an in-die lamination method in which they are brought into contact along a path inside a mold, such as a multi-manifold die, and an out-die lamination method in which they are discharged from multiple concentric lips and brought into contact. For example, in the in-die lamination method, a multi-layer die such as a three-layer multi-manifold die can be used to form a three-layer structure of layer b / layer a / layer b, consisting of a surface layer (heat seal layer: layer b) and a core layer (intermediate layer: layer a).

[0109] Examples of lamination methods include extrusion lamination, which uses equipment for melt extrusion molding used in the T-die method to extrude a film of molten resin directly onto another film to form a laminated film.

[0110] Examples of heat sealing methods include an external heating method in which a heated metal body is pressed against multiple bonded films from the outside of the films, and the conducted heat melts and bonds the films, and an internal heating method in which high-frequency radio waves or ultrasound are used to generate heat in the films and bond them.

[0111] In the manufacturing method A, the above lamination methods can be used alone or in combination.

[0112] In manufacturing method A, when producing a biaxially stretched laminate film, a resin sheet (raw sheet) having the above-described laminate structure is biaxially stretched. As the stretching method, known methods such as stretching between rolls with different peripheral speeds, a tenter method, and a tubular method can be used. For biaxial stretching, both sequential stretching and simultaneous stretching are applicable. Of these, simultaneous biaxial stretching by a tenter method, sequential biaxial stretching by a tenter method, and sequential biaxial stretching in which longitudinal (flow, MD) stretching between rolls with different peripheral speeds is followed by transverse (width, TD) stretching by a tenter method are preferred because they facilitate the production of the desired stretched film. Hereinafter, a method for obtaining the stretched film of the present invention by sequential biaxial stretching will be described, but the method is not limited thereto.

[0113] In the sequential biaxial stretching method, it is preferable to adjust the stretching temperature and stretch ratio depending on the melting point and glass transition temperature of the resin used. First, a resin sheet (raw sheet) is maintained at a temperature of preferably 100 to 180°C, more preferably 120 to 170°C, and stretched in the machine direction by preferably 2 to 10 times, more preferably 2.5 to 8 times, and even more preferably 3 to 6 times by passing it between rolls with different peripheral speeds or by a tenter method. Subsequently, the stretched film is stretched in the transverse direction by a tenter method at a temperature of preferably 100 to 180°C, more preferably 120 to 175°C, by preferably 2 to 12 times, more preferably 2.5 to 11.5 times, and even more preferably 3 to 11 times, followed by relaxation, heat setting, and winding.

[0114] The wound film is preferably subjected to an aging treatment in an atmosphere of about 20 to 45° C., and then cut to the desired product width. In this way, a stretched film excellent in stretchability, transparency, mechanical strength, etc. is obtained.

[0115] A preferred embodiment of manufacturing method A includes a step of providing a heat-sealable layer b on one side of layer a and a skin layer c on the opposite side of layer a, and then providing a monolayer section made of crystalline thermoplastic resin A at both lateral ends of the resulting laminated sheet to form a resin sheet, and then gripping and stretching at least the monolayer sections that form both ends. This method can provide low-tack monolayer sections at both lateral ends using a feed block and a monolayer T-die. The monolayer sections are gripped with clips and stretched at least in the lateral direction using a tenter method, followed by trimming to obtain a multilayer stretched film comprising layer a, heat-sealable layer b, and skin layer c. The width of the monolayer section (on one side) is not particularly limited, but is preferably about 1 to 30%, more preferably about 2 to 30%, of the total width of the unstretched resin sheet. [Example]

[0116] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0117] The resins used in the examples and comparative examples are as follows.

[0118] (Crystalline thermoplastic resin A) Resin A: Prime Polypro (registered trademark) F-300SP (homopolypropylene, manufactured by Prime Polymer Co., Ltd., melting point 163°C) (Biomass Plastic B) Resin B: Luminy® LX175 (Total Corbion PLA, polylactic acid, 5% D-form) (Thermoplastic resin C; Compatibilizer) Resin C: Dynaron 9901P (styrene-ethylene-butylene-styrene block copolymer, manufactured by JSR Corporation) (Thermoplastic resin D) Resin D-1: DF740 (Mitsui Chemicals, Inc., ethylene-propylene copolymer, melting point 55°C) Resin D-2: Toughmer XM7070S (Mitsui Chemicals, Inc., propylene-1-butene copolymer, melting point 75°C) Resin D-3: 5C37F (manufactured by SunAllomer Co., Ltd., ethylene-propylene-1-butene copolymer, melting point 132°C) Resin D-4: F-724NPC (Prime Polymer, propylene-ethylene random copolymer, melting point 146°C) (Resin E that forms the heat seal layer) Resin E-1: TAFMER XM7070S (Mitsui Chemicals, Inc., propylene-1-butene copolymer, melting point 75°C) Resin E-2: 5C37F (manufactured by SunAllomer Co., Ltd., ethylene-propylene-1-butene copolymer, melting point 132°C) (Crystalline polyolefin resin F) Resin F: Prime Polypro (registered trademark) F-300SP (homopolypropylene, manufactured by Prime Polymer Co., Ltd., melting point 163°C)

[0119] [Resin melting point] The melting points of the resins used in the examples and comparative examples were calculated using a Perkin-Elmer Diamond DSC (power compensation type DSC) according to the following procedure. Five mg of each resin was weighed out, placed in an aluminum sample holder, and placed in the DSC instrument. Under a nitrogen flow, the sample was heated from -40°C to 300°C at a rate of 20°C / min, held at 300°C for 5 minutes, cooled to -40°C at 20°C / min, and held at -40°C for 5 minutes. The melting points were then determined from the DSC curves obtained when the sample was heated again to 300°C at 20°C / min.

[0120] [Film thickness] The thickness of the laminated film obtained in each of the Examples and Comparative Examples was measured using a paper thickness measuring instrument MEI-11 manufactured by Citizen Seimitsu Co., Ltd. in accordance with JIS-C2330.

[0121] [Heat sealability evaluation method] Two sheets of laminated film obtained in each Example and Comparative Example were each cut to a length of 250 mm in the MD and 50 mm in the TD to prepare measurement samples. These two measurement samples were overlapped with each other, heat-sealed, at 23°C and 50% RH. In this state, a heat-sealing process was performed using a thermal gradient heat sealer HG-100-2 (manufactured by Toyo Seiki Seisakusho Co., Ltd.) under the following conditions: sealing temperature: 120°C, sealing pressure: 200 KPa, sealing time: 2 seconds, and heat-seal width (corresponding to the MD of the film): 1 cm. Heat-sealability (heat-seal strength) was evaluated using the following measurement method.

[0122] <Method for measuring heat seal strength> Using a tensile testing machine (Minebea Co., Ltd. TechnoGraph TGI-1KN), the maximum stress (N) was measured by peeling two heat-sealed laminated films with a T-peel at a temperature of 23°C and a relative humidity of 50%RH, using a 1KN load cell, a chuck distance of 30 mm, and a movement speed of 300 mm / min. The measurement was performed five times and the average value was calculated.

[0123] Tensile modulus The tensile modulus of elasticity of the laminated films obtained in each of the Examples and Comparative Examples was measured in accordance with JIS P 8113. Specifically, the tensile modulus was measured at a temperature of 23°C and a relative humidity of 50% RH using a tensile tester (manufactured by L&W, Tensile Tester CODE SE-064).

[0124] Example 1 As shown in Table 1 below, 66.5 parts by mass of pellets of Resin A (crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 °C, glass transition temperature -7 °C) were used as the resin component A for forming Layer a. 16 parts by mass of pellets of Resin B (biomass plastic, MFR = 8 g / 10 min, melting point 155 °C, glass transition temperature 57 °C) were used as the resin component B for forming Layer a. 10 parts by mass of pellets of Resin C were used as the resin component C for forming Layer a. 7.5 parts by mass of Resin D-3 (ethylene-propylene-1-butene copolymer, melting point 132 °C) were used as the resin component D for forming Layer a. These were then dry-blended in a mixer to prepare Resin Raw Material A for Layer a. Furthermore, pellets of Resin F were used as Resin Raw Material B for Outer Layer 1 (heat-sealable layer b). Furthermore, pellets of Resin E-1 were used as Resin Raw Material C for Outer Layer 2 (skin layer c).

[0125] The obtained resin raw material a was fed from a hopper into an apparatus consisting of a Laboplastomill (registered trademark) (Model 4C150) manufactured by Toyo Seiki Seisaku-sho, Ltd., connected to a twin-screw extruder (L / D = 25) equipped with a strand die, and melt-kneaded at a set temperature of 260°C. The resin raw material was extruded in the form of a strand, cooled with water, and then cut into pellets with a strand cutter to obtain pellets a. Pellet b of resin raw material b and pellet c of resin raw material c were obtained in the same manner.

[0126] Pellet a was fed into single-screw extruder a via a hopper, and pellet b was fed into single-screw extruder b via a hopper, separate from extruder a. Furthermore, pellet c was fed into single-screw extruder c via a hopper, separate from extruders a and b. Pellet a, pellet b, and pellet c were each melted and laminated in a three-layer multi-manifold die to form a three-layer structure consisting of b (outer layer 1), a (intermediate layer), and c (outer layer 2), extruding the resulting three-layer laminated resin layer. The ratio of the extrusion resin amounts from single-screw extruder a, single-screw extruder b, and single-screw extruder c was 2:1:1. The extruded resin layer was cooled and solidified by pressing it onto a cooling drum (controlled at 45°C) using an air knife under air pressure, yielding a raw sheet.

[0127] The resulting raw sheet was stretched using a Bruckner KARO batch-type biaxial stretching machine. The stretching method was a sequential biaxial stretching method, in which the film was stretched in the machine direction and then in the transverse direction. The film was preheated in an oven set at 150°C until the film temperature (Ts) reached 135°C, and then stretched 5x in the machine direction at a stretching speed of 6x / sec. Next, the film was preheated in an oven set at 165°C until the film temperature reached 145°C, and then stretched 10x in the transverse direction at a stretching speed of 1x / sec. Next, in the same oven, the film was relaxed in the transverse direction at a relaxation speed of 0.5x / sec to 9.5x, then heat-set for 10 seconds, removed from the oven, and cooled to room temperature, yielding a biaxially stretched laminate film with a thickness of 30 μm.

[0128] (Examples 2 to 10, Comparative Examples 1 to 7) A 30 μm thick laminate film was obtained in the same manner as in Example 1, except that resin raw material a, resin raw material b, and resin raw material c were prepared by setting the types and amounts of component A resin, component B resin, component C resin, and component D resin for forming layer a, and the types of resins for forming outer layer 1 (heat seal layer b) and outer layer 2 (skin layer c) as shown in Table 1 below. The laminate films obtained in Examples 2 to 9 and Comparative Examples 1 to 6 were biaxially stretched, but the laminate films obtained in Example 10 and Comparative Example 7 were not stretched.

[0129] [Table 1]

[0130] (In Table 1, the melting points are in °C.) The production conditions and evaluation results for the laminated films obtained in each example and comparative example are shown in Table 1. Comparing comparative examples 6 and 7 with comparative examples 1 and 2, it is clear that the heat sealability (heat seal strength) of laminated films containing biomass plastics is a problem, but the laminated films obtained in the examples have good heat sealability (heat seal strength) despite being laminated films containing biomass plastics.

Claims

1. A laminated film comprising at least a layer a and a heat-sealable layer b, (1) The laminated film contains biomass plastic, (2) The heat seal layer b contains a polyolefin resin PO1 having at least one melting peak temperature of 60°C or higher and 145°C or lower, (3) The layer a contains the polyolefin resin PO1 and a polyolefin resin PO2 having at least one melting peak temperature of 155°C or higher, (4) A laminated film characterized in that the polyolefin-based resin PO1 and the polyolefin-based resin PO2 satisfy at least one of the following conditions (I) to (IV): (I) The content PO1 of the polyolefin resin PO1 in the layer a ａ is 6% by mass or more, (II) Content PO1 of the polyolefin resin PO1 in the laminated film Ｆ is 15% by mass or more, (III) The content PO2 of the polyolefin resin PO2 in the layer a ａ The content PO1 of the polyolefin resin PO1 ａ Mass ratio of [PO1 ａ / PO2 ａ ] is 0.09 or more, (IV) The content (PO2) of the polyolefin resin (PO2) in the laminated film Ｆ The content PO1 of the polyolefin resin PO1 Ｆ Mass ratio of [PO1 Ｆ / PO2 Ｆ ] is 0.23 or more.

2. 2. The laminated film according to claim 1, wherein the layer a and the heat-sealable layer b are directly laminated together.

3. 3. The laminated film according to claim 1, which has a heat seal strength of 5 N / 25 mm or more at 120°C.

4. The laminated film is biaxially stretched, and further characterized in that the polyolefin-based resin PO1 and the polyolefin-based resin PO2 satisfy at least one of the following conditions (V) to (VIII): (V) The content PO2 of the polyolefin resin PO2 in the layer a ａ is 45% by mass or more, (VI) The content PO2 of the polyolefin resin PO2 in the laminated film Ｆ is 48% by mass or more, (VII) The content PO2 of the polyolefin resin PO2 in the layer a ａ The content PO1 of the polyolefin resin PO1 ａ Mass ratio of [PO1 ａ / PO2 ａ ] is 0.6 or less, (VIII) The content PO2 of the polyolefin resin PO2 in the laminated film Ｆ The content PO1 of the polyolefin resin PO1 Ｆ Mass ratio of [PO1 Ｆ / PO2 Ｆ ] is less than 0.

7.

5. A laminate comprising the laminate film according to any one of claims 1 to 4 and a substrate.

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