Sealant films, laminates, packaging materials, and packaging containers

Abstract

To provide a sealant film that is excellent in terms of slip resistance, suitability for low-temperature heat sealing, and recyclability. [Solution] The sealant film 10 of this disclosure comprises an outer layer 12, an intermediate layer 13, and an inner layer 14 in this order, the inner layer 14 constituting one side of the sealant film 10, the outer layer 12 mainly containing polypropylene, the intermediate layer 13 containing polypropylene and a propylene-based elastomer, and the density of the intermediate layer 13 is 0.85 g / cm³. 3 More than 0.89g / cm 3 The following is a characteristic feature: the inner layer 14 contains polypropylene and silylated polyolefin, and the thickness of the inner layer 14 is 0.5 μm or more and 3 μm or less.

Description

[Technical Field]

[0001] This disclosure relates to sealant films, laminates, packaging materials, and packaging containers. [Background technology]

[0002] In many product sectors, including food, beverages, pharmaceuticals, and chemicals, packaging materials and containers have been developed to suit the specific contents. In particular, for packaging containers containing viscous substances such as liquids, semi-solids, and gels, resins with excellent water resistance, oil resistance, gas barrier properties, lightweight, flexibility, and design qualities are used to protect the contents.

[0003] One of the functions required of packaging containers is the ability to prevent the contents from adhering to the inner surface of the container and remaining inside (slippage). Many efforts have been made to prevent contents from adhering to the inner surface of packaging containers and to improve slippage.

[0004] Patent Document 1 describes a heat-sealable resin film having an uneven surface structure. By having an uneven surface structure on the heat-sealable resin film, the contact area with the contents is reduced, improving the slipperiness of the heat-sealable resin film.

[0005] Patent Document 2 describes a liquid-repellent film comprising at least a base layer, a heat-seal layer, and a liquid-repellent layer laminated in that order. The liquid-repellent film exhibits liquid-repellent properties to liquid-containing contents because the liquid-repellent layer that comes into contact with the contents contains at least an oil-repellent silicone-containing resin.

[0006] Patent Document 3 describes a water-repellent packaging material having a heat-sealable resin composition layer on one side of the substrate, comprising at least hydrophobic fine particles, a silane coupling agent, and a thermoplastic resin. This water-repellent packaging material can prevent the contents from adhering to the substrate.

[0007] Patent Document 4 describes a linear polyethylene film in which a heat-sealing layer formed by mixing a predetermined shaped organic particle A, a predetermined amorphous inorganic particle B, and a predetermined lubricant C constitutes a heat-sealing surface. This linear polyethylene film exhibits slipperiness.

[0008] Patent Document 5 describes a resin composition for extrusion lamination, which contains 0.01 to 1.0 parts by weight of a predetermined glycerin monofatty acid ester and 0.01 to 0.3 parts by weight of a predetermined fatty acid amide with respect to 100 parts by weight of an ethylene polymer. By adopting this resin composition for extrusion lamination as the innermost layer of a laminate, the slipperiness is improved.

[0009] Patent Document 6 describes a water-repellent laminate for a lid material, which includes a base material, a heat-adhesive layer on the base material, and a water-repellent layer on the heat-adhesive layer. In this water-repellent laminate for a lid material, water-repellent fine particles are attached to the surface opposite to the surface on the heat-adhesive layer side of the water-repellent layer, and the fine particles exhibit water-repellent performance without being buried in the layer.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0011] In recent years, bag-making machines have become faster, and there is a growing demand for rapid heat sealing when manufacturing packaging bags by heat-sealing the sealant films of packaging materials together. If heat sealing can be performed at low temperatures, the resin constituting the sealant film can be melted in a short time, enabling rapid heat sealing. Therefore, low-temperature heat-sealability is required for sealant films.

[0012] Furthermore, in recent years, with the growing demand for the creation of a circular economy, attempts have been made to recycle and reuse packaging materials and bags. Packaging materials composed of different types of resins, such as by laminating multiple different resin films, are not suitable for recycling because it is difficult to separate the resins by type. In order to manufacture packaging materials that are easy to recycle and have a low environmental impact, there is a need to make sealant films used in packaging materials composed of the same type of resin as much as possible (single material, monomaterialization).

[0013] Therefore, the object of this disclosure is to provide a sealant film that is excellent in slip resistance, suitability for low-temperature heat sealing, and recyclability. Another object of this disclosure is to provide a laminate comprising the sealant film, a packaging material comprising the laminate, and a packaging container using the packaging material. [Means for solving the problem]

[0014] This disclosure is resolved by the following embodiments. <1> A sealant film comprising an outer layer, an intermediate layer, and an inner layer in this order, The inner layer constitutes one surface of the sealant film. The outer layer contains polypropylene as its main component, The aforementioned intermediate layer contains polypropylene and a propylene-based elastomer. The density of the aforementioned intermediate layer is 0.85 g / cm³. 3 More than 0.89g / cm3 The following: The inner layer contains polypropylene and silylated polyolefin, A sealant film having an inner layer thickness of 0.5 μm or more and 3 μm or less. <2> The propylene-based elastomer is a propylene-ethylene copolymer. <1> The sealant film described above. <3> The content of α-olefin units relative to all constituent units of the propylene-based elastomer is 3% by mass or more and 20% by mass or less. <1> or <2> The sealant film described above. <4> The content of the propylene-based elastomer in the intermediate layer is 30% by mass or more and 95% by mass or less. <1> ~ <3> A sealant film as described in one of the following. <5> The silylated polyolefin is a reaction product of a silicon-containing compound having two or more SiH groups in its molecule and a vinyl group-containing compound having a vinyl group at the end of the olefin polymer. <1> ~ <4> A sealant film as described in one of the following. <6> The content of the silylated polyolefin in the inner layer is 3% by mass or more and 30% by mass or less. <1> ~ <5> A sealant film as described in one of the following. <7> The outer layer comprises a first layer, a second layer, and a third layer in this order. The first layer contains propylene random copolymer as its main component, The second layer contains propylene random copolymer as its main component, The third layer contains propylene homopolymer as its main component. <1> ~ <6> A sealant film as described in one of the following. <8> <1> ~ <7> A laminate comprising a sealant film and a substrate as described in any one of the following. <9> The aforementioned substrate is a polypropylene resin substrate containing polypropylene as the main component. <8> The laminate described above. <10> <8> or <9> A packaging material comprising the laminate described above. <11> <10> A packaging container using the packaging materials described above. [Effects of the Invention]

[0015] According to this disclosure, a sealant film can be provided that is excellent in slip resistance, suitability for low-temperature heat sealing, and recyclability. Furthermore, this disclosure provides a laminate comprising the sealant film, a packaging material comprising the laminate, and a packaging container using the packaging material. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the sealant film of the present disclosure. [Figure 2] This is a schematic cross-sectional view showing one embodiment of the sealant film of the present disclosure. [Figure 3] This is a schematic cross-sectional view showing one embodiment of the laminate of the present disclosure. [Figure 4] This is a schematic cross-sectional view showing one embodiment of the laminate of the present disclosure. [Figure 5] This is a perspective view showing a packaging bag, which is one embodiment of the packaging container in this disclosure. [Figure 6] This is a perspective view showing a packaging bag, which is one embodiment of the packaging container in this disclosure. [Modes for carrying out the invention]

[0017] In this specification, when multiple upper limit candidates and multiple lower limit candidates are given for a certain parameter, the numerical range of that parameter may be constructed by combining any one upper limit candidate and any one lower limit candidate. As an example, consider the statement, "Parameter B is preferably A1 or greater, more preferably A2 or greater, even more preferably A3 or greater, and also preferably A4 or less, more preferably A5 or less, and even more preferably A6 or less." In this example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, and A3 or greater and A6 or less.

[0018] The embodiments of this disclosure will be described in detail below. This disclosure can be implemented in many different forms and is not construed as being limited to the embodiments described below. The drawings may schematically represent the width, thickness, and shape of each layer, etc., compared to the embodiments, in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. In this specification and in each figure, elements similar to those already described in the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0019] Each of the components mentioned in the following description (for example, polypropylene, α-olefin, resin material, additive, propylene-based elastomer, and silylated polyolefin) may be used individually or in combination of two or more.

[0020] In this specification, "main component" in a given layer means a component whose content in that layer is greater than 50% by mass, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0021] [Sealant film] The sealant film of this disclosure comprises an outer layer, an intermediate layer, and an inner layer in this order.

[0022] The sealant film is preferably an unstretched film. An unstretched film means a film that has not undergone intentional stretching (a film whose molecules have not been oriented by stretching). Details of the stretching process will be described later. Films that are inevitably stretched during extrusion molding or film winding are also included in the category of unstretched films.

[0023] The sealant film 10 shown in Figure 1 comprises an outer layer 12, an intermediate layer 13, and an inner layer 14 in that order. The inner layer 14 constitutes one surface of the sealant film 10. The outer layer 12 constitutes the other surface of the sealant film 10. The sealant film 10 shown in Figure 2 comprises an outer layer 12, an intermediate layer 13, and an inner layer 14 in that order. The outer layer 12 comprises a first layer 12a, a second layer 12b, and a third layer 12c in that order. The inner layer 14 constitutes one surface of the sealant film 10. The first layer 12a constitutes the other surface of the sealant film 10.

[0024] The sealant film comprising an outer layer, an intermediate layer, and an inner layer is preferably an unstretched resin film, more preferably an unstretched co-extruded resin film manufactured by a co-extrusion T-die-casting method, wherein each layer constituting the resin film is a co-extruded resin layer. In one embodiment, the resin film is a co-extruded resin film with three or more layers, preferably a co-extruded resin film with three to nine layers, and more preferably a co-extruded resin film with five to seven layers. Multilayer co-extrusion allows for the production of thin layers constituting the sealant film. In one embodiment, the resin film is an unstretched resin film obtained by manufacturing the material constituting the outer layer, the material constituting the intermediate layer, and the material constituting the inner layer by a co-extrusion T-die-casting method. Such a sealant film, for example, exhibits excellent heat-sealability.

[0025] One embodiment of co-extrusion T-die casting is described below. A sealant film is obtained by supplying materials for forming each layer to each extruder, extruding a fixed amount using the gear pump of the extruder, supplying it to a multi-manifold die, and performing co-extrusion casting. For example, in each extruder, the temperature of the screw that extrudes the material constituting the outer layer is set to 240°C or more and 260°C or less, the temperature of the screw that extrudes the material constituting the intermediate layer is set to 230°C or more and 240°C or less, and the temperature of the screw that extrudes the material constituting the inner layer is set to 230°C or more and 240°C or less.

[0026] The polypropylene content in the sealant film is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more. Such a sealant film is preferable, for example, from the viewpoint of recyclability. The polypropylene content in the sealant film refers to the ratio of the polypropylene content to the sum of the resin material content in each layer constituting the sealant film.

[0027] The thickness of the sealant film is preferably 6 μm or more, more preferably 12 μm or more, preferably 110 μm or less, and more preferably 60 μm or less. Sealant films with a thickness greater than or equal to the lower limit have excellent properties such as strength, heat sealability, and recyclability. Sealant films with a thickness less than or equal to the upper limit have excellent properties such as processability. In this specification, the thickness of the sealant film and each layer is the average value of 10 thicknesses measured based on scanning electron microscope (SEM) images obtained by observing a cross-section perpendicular to the film surface.

[0028] <Outer layer> In one embodiment, the outer layer contains polypropylene as the main component, i.e., in an amount exceeding 50% by mass. The sealant film having the outer layer exhibits excellent oil resistance, for example.

[0029] Polypropylene may be any of the following: propylene homopolymer (homopolypropylene), propylene random copolymer (random polypropylene) such as propylene-α-olefin random copolymer, or propylene block copolymer (block polypropylene) such as propylene-α-olefin block copolymer, or a mixture of two or more selected from these. From the viewpoint of reducing environmental impact, biomass-derived polypropylene or mechanically or chemically recycled polypropylene may be used as the polypropylene.

[0030] A propylene homopolymer is a polymer composed solely of propylene. A propylene random copolymer is a random copolymer of propylene and α-olefins other than propylene. A propylene block copolymer is a copolymer having polymer blocks made of propylene and polymer blocks made of α-olefins other than propylene.

[0031] Examples of α-olefins other than propylene include α-olefins having 2 to 20 carbon atoms, specifically ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.

[0032] Among polypropylenes, propylene random copolymer is preferable from the viewpoint of transparency. When rigidity and heat resistance of the packaging container are important, propylene homopolymer is preferable. When impact resistance of the packaging container is important, propylene block copolymer is preferable.

[0033] The density of polypropylene is, for example, 0.88 g / cm³. 3 More than 0.92g / cm 3The following applies: The melting point (Tm) of polypropylene is preferably 120°C or higher, more preferably 125°C or higher, preferably 170°C or lower, and more preferably 165°C or lower, from the viewpoint of strength, heat resistance, and heat sealability. In this disclosure, Tm is the melting peak temperature obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121:2012.

[0034] From the viewpoint of the processability of the sealant film, the melt flow rate (MFR) of polypropylene is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, even more preferably 1.5 g / 10 min or more, and even more preferably 2 g / 10 min or more. From the viewpoint of cast film formation properties, the polypropylene MFR is preferably 50 g / 10 min or less, more preferably 40 g / 10 min or less, even more preferably 30 g / 10 min or less, even more preferably 20 g / 10 min or less, and particularly preferably 10 g / 10 min or less. In this disclosure, the MFR of polypropylene is measured by Method A under a load of 2.16 kg in accordance with JIS K7210-1:2014. The measurement temperature for the MFR is, for example, 230°C.

[0035] The polypropylene content in the outer layer is preferably more than 50% by mass, for example, 55% or more by mass or 60% or more by mass, more preferably 80% or more by mass, even more preferably 85% or more by mass, even more preferably 90% or more by mass, and particularly preferably 93% or more by mass.

[0036] The outer layer may contain resin materials other than polypropylene. Examples of such resin materials include polyethylene, (meth)acrylic resin, vinyl resin, cellulose resin, polyamide, polyester, and ionomer resin.

[0037] The outer layer may contain additives. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, compatibilizers, pigments, and modifying resins.

[0038] In one embodiment, the outer layer may be surface-treated. This can improve, for example, the adhesion between the outer layer and other layers. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the outer layer.

[0039] The sealant film may have two or more outer layers. The number of outer layers is preferably two or more, more preferably three or more, preferably seven or fewer, and more preferably five or fewer.

[0040] The thickness of the outer layer is preferably 5 μm or more, more preferably 10 μm or more, preferably 100 μm or less, and more preferably 50 μm or less. When the sealant film has two or more outer layers, it is preferable that the total thickness of the outer layers is within the above range. A sealant film having an outer layer with a thickness equal to or greater than the lower limit has, for example, excellent strength, heat resistance, and recyclability. A sealant film having an outer layer with a thickness equal to or less than the upper limit has, for example, excellent processability.

[0041] In one embodiment, the outer layer comprises, in this order, a first layer mainly containing propylene random copolymer, a second layer mainly containing propylene random copolymer, and a third layer mainly containing propylene homopolymer. The first and second layers can, for example, contribute to improving adhesion with adjacent layers. The third layer can, for example, contribute to improving the rigidity of the sealant film. The outer layer may comprise two or more third layers. A sealant film with such an outer layer exhibits, for example, an excellent balance of interlayer adhesion, strength, and rigidity.

[0042] In the above embodiment, the thickness of the first and second layers is preferably 3% or more, more preferably 5% or more, even more preferably 7% or more, preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less, with respect to the total thickness of the outer layer. In the above embodiment, the total thickness of the third layer is preferably 40% or more, more preferably 50% or more, preferably 94% or less, and even more preferably 90% or less, with respect to the total thickness of the outer layer.

[0043] In one embodiment, the melting point of the third layer is higher than that of the first layer, and the melting point of the third layer is higher than that of the second layer. The melting points of the above layers are obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121:2012.

[0044] <Middle class> In one embodiment, the intermediate layer contains polypropylene and a propylene-based elastomer. The sealant film having the intermediate layer exhibits excellent low-temperature heat sealability.

[0045] The polypropylene content in the intermediate layer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 30% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and particularly preferably 40% by mass or less. The characteristics of the polypropylene contained in the intermediate layer are the same as those of the polypropylene contained in the outer layer, so they are omitted from this description.

[0046] Elastomers are a general term for polymers that deform in accordance with an applied external force and quickly return to their original shape when the force is removed. Elastomers are generally composed of a hard segment that governs basic physical properties such as mechanical properties, and a soft segment that governs the elasticity, a property of rubber. Propylene elastomers are those in which the hard segment is made of polypropylene. The characteristics of the polypropylene that constitutes the hard segment of the propylene-based elastomer are the same as those of the polypropylene contained in the outer layer, so the description is omitted here.

[0047] The propylene-based elastomer is not particularly limited as long as it has compatibility with polyolefin and a low melting point. Examples thereof include copolymers of propylene and α-olefins. Examples of the α-olefin include α-olefins having 2 to 8 carbon atoms such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. More specifically, examples include propylene-ethylene copolymers, propylene-ethylene-1-butene copolymers, 1-butene-propylene copolymers, 4-methylpentene-1-propylene copolymers, 4-methylpentene-1-propylene-1-butene copolymers, propylene-1-butene copolymers, and ethylene-propylene copolymers.

[0048] The content rate of the α-olefin unit with respect to all the constitutional units constituting the propylene-based elastomer is preferably 3% by mass or more, more preferably 10% by mass or more, and preferably 20% by mass or less. If the content rate of the α-olefin unit, which is the soft segment, is within the above range, excellent flexibility and excellent stretchability can be imparted to the sealant film.

[0049] From the viewpoint of improving the heat sealability, the melting point (Tm) of the propylene-based elastomer is preferably 140 °C or lower, more preferably 135 °C or lower. The lower limit of Tm is not particularly limited, but is, for example, 70 °C, 80 °C, or 90 °C.

[0050] The density of the propylene-based elastomer is preferably 0.850 g / cm 3 or more, more preferably 0.860 g / cm 3 or more, still more preferably 0.870 g / cm 3 or more, and preferably 0.920 g / cm 3 or less, more preferably 0.915 g / cm 3More preferably, 0.910 g / cm³ 3 The following applies:

[0051] The MFR of the propylene-based elastomer is preferably 0.2 g / 10 min or more, more preferably 0.3 g / 10 min or more, even more preferably 0.5 g / 10 min or more, preferably 20 g / 10 min or less, more preferably 15 g / 10 min or less, even more preferably 10 g / 10 min or less, and particularly preferably 5 g / 10 min or less, from the viewpoint of film-forming properties and processability. The MFR of the propylene-based elastomer is measured by Method A in accordance with JIS K7210-1:2014, under conditions of a temperature of 190°C and a load of 2.16 kg.

[0052] The content of propylene-based elastomer in the intermediate layer is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, particularly preferably 60% by mass or more, preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less. As a result, the sealant film exhibits excellent low-temperature heat sealability.

[0053] The intermediate layer may contain resin materials other than polypropylene and propylene-based elastomers. Examples of such resin materials include polyethylene, (meth)acrylic resin, vinyl resin, cellulose resin, polyamide, polyester, and ionomer resin.

[0054] The intermediate layer may contain additives. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, compatibilizers, pigments, and modifying resins.

[0055] In one embodiment, the intermediate layer may be surface-treated. This can improve, for example, the adhesion between the intermediate layer and the other layers. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the intermediate layer.

[0056] The sealant film may have two or more intermediate layers. The number of intermediate layers is preferably two or more, more preferably three or more, preferably seven or fewer, and more preferably five or fewer.

[0057] The thickness of the intermediate layer is preferably 5 μm or more, more preferably 10 μm or more, preferably 100 μm or less, and more preferably 50 μm or less. When the sealant film has two or more intermediate layers, it is preferable that the total thickness of the intermediate layers is within the above range. A sealant film having an intermediate layer with a thickness equal to or greater than the lower limit has, for example, excellent strength, heat resistance, and recyclability. A sealant film having an intermediate layer with a thickness equal to or less than the upper limit has, for example, excellent processability.

[0058] The density of the intermediate layer is 0.89 g / cm³. 3 The following, preferably 0.88 g / cm³ 3 The following, and preferably 0.85 g / cm³ 3 More preferably 0.86 g / cm³ 3 More preferably 0.87 g / cm³ 3 That's all. The density of the intermediate layer is the value measured after annealing as described in JIS K6760:1995, according to the method specified in Method A of JIS K7112:1980.

[0059] <Inner layer> The inner layer contains polypropylene and silylated polyolefin. A sealant film with an inner layer exhibits, for example, excellent slip resistance. The characteristics of the polypropylene contained in the inner layer are the same as those of the polypropylene contained in the outer layer, so they are omitted here.

[0060] Silylated polyolefins are reaction products of a silicon-containing compound having two or more SiH groups in its molecule and a vinyl group-containing compound, which is a polymer of at least one olefin selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, and 1-hexene, and which contains a vinyl group at its terminus.

[0061] Examples of silicon-containing compounds having two or more SiH groups include, for example, methylhydrogenpolysiloxane represented by formula (1), and compounds in which some or all of the methyl groups in formula (1) are substituted with ethyl groups, propyl groups, phenyl groups, trifluoropropyl groups, etc.

[0062] Formula (1) (CH3)3SiO-(-SiH(CH3)-O-) a -Si(CH3)3 (In formula (1), a is an integer of 2 or more, with an upper limit preferably of 1000, more preferably of 300, and more preferably of 50.)

[0063] Other examples of silicon-containing compounds having two or more SiH groups include, for example, the dimethylsiloxane-methylhydrogensiloxane copolymer represented by formula (2), and compounds in which some or all of the methyl groups in formula (2) are substituted with ethyl groups, propyl groups, phenyl groups, trifluoropropyl groups, etc.

[0064] Formula (2) (CH3)3SiO-(-Si(CH3)2-O-) b -(-SiH(CH3)-O-) c -Si(CH3)3 (In formula (2), b is an integer of 1 or more, c is an integer of 2 or more, and the upper limit of the sum of b and c is preferably 1000, more preferably 300, and more preferably 50.)

[0065] In equation (2), there are no particular restrictions on the order in which the -Si(CH3)2-O- units and -SiH(CH3)-O- units are arranged; they may be in blocks, disordered, or statistically random.

[0066] Further examples of silicon-containing compounds having two or more SiH groups include, for example, methylhydrogenpolysiloxane represented by formula (3), and compounds in which some or all of the methyl groups in formula (3) are substituted with ethyl groups, propyl groups, phenyl groups, trifluoropropyl groups, etc.

[0067] Formula (3) HSi(CH3)2O-(-Si(CH3)2-O-) d -Si(CH3)2H (In formula (3), d is an integer of 1 or more, and its upper limit is preferably 1000, more preferably 300, and more preferably 50.)

[0068] More specifically, such compounds include, but are not limited to, compounds whose number-average molecular weight corresponds to the structure shown below. HSi(CH3)2O-(-Si(CH3)2-O-)5-Si(CH3)2H HSi(CH3)2O-(-Si(CH3)2-O-)8-Si(CH3)2H HSi(CH3)2O-(-Si(CH3)2-O-) 18 -Si(CH3)2H HSi(CH3)2O-(-Si(CH3)2-O-) 80 -Si(CH3)2H HSi(CH3)2O-(-Si(CH3)2-O-) 230 -Si(CH3)2H

[0069] The vinyl group-containing compound is preferably an ethylene-α-olefin copolymer in which 81 to 100 mol% of the constituent units derived from ethylene and 0 to 19 mol% of the constituent units derived from α-olefins having 3 to 20 carbon atoms are in the range of 1. More preferably, it is an ethylene-α-olefin copolymer in which 90 to 100 mol% of the constituent units derived from ethylene and 0 to 10 mol% of the constituent units derived from α-olefins having 3 to 20 carbon atoms are in the range of 1. In particular, it is preferable that the constituent units derived from ethylene be 100 mol%.

[0070] Furthermore, it is preferable that the vinyl group-containing compound has a molecular weight distribution (ratio of weight-average molecular weight to number-average molecular weight, Mw / Mn) measured by gel permeation chromatography (GPC) in the range of 1.1 to 3.0.

[0071] The number-average molecular weight (Mn) of the vinyl group-containing compound, as determined by the GPC method, is preferably 100 or more, more preferably 500 or more, even more preferably 1500 or more, and also preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 100,000 or less.

[0072] The melting point of the vinyl group-containing compound is preferably between 70°C and 130°C.

[0073] Furthermore, the vinyl group in the vinyl group-containing compound is preferably located at the end of the main chain, and more preferably the vinyl group is located only at the end of the main chain.

[0074] Furthermore, if a vinyl group-containing compound contains vinyl groups only at the ends of the main chain, 1 The terminal unsaturation rate calculated by 1H-NMR is preferably 80 mol% or more, more preferably 90 mol% or more, and also preferably 99.5 mol% or less, and more preferably 99 mol% or less.

[0075] The silylated polyolefin is a silylated polyolefin or its derivative, or a mixture thereof, obtained by reacting the aforementioned vinyl group-containing compound with a silicon-containing compound in the presence of a transition metal catalyst, according to the method described in Japanese Patent Application Publication No. 2014-223752.

[0076] Specific examples of silylated polyolefins include those having structures represented by formulas (4) to (6), but the combinations of silicon-containing compounds and vinyl group-containing compounds are not limited to these examples.

[0077] Formula (4) (CH3)3SiO-(-Si[CH2-(CH2) n-2 -CH3](CH3)-O-) a -Si(CH3)3 (In formula (4), a is an integer of 2 or more, and its upper limit is preferably 1000, more preferably 300, and more preferably 50.)

[0078] Formula (5) (CH3)3SiO-(-Si(CH3)2-O-) b -(-Si[CH2-(CH2) n-2 -CH3](CH3)-O-) c -Si(CH3)3 (In formula (5), b is an integer of 1 or more, c is an integer of 2 or more, and the upper limit of the sum of b and c is preferably 1000, more preferably 300, and more preferably 50.)

[0079] Formula (6) CH3-(CH2) n-2 -CH2-Si(CH3)2O-(-Si(CH3)2-O-) d -Si(CH3)2-CH2-(CH2) n-2 -CH3 (In formula (6), d is an integer of 1 or more, with an upper limit preferably of 1000, more preferably of 300, more preferably of 50, and particularly preferably of 25.)

[0080] The silylated polyolefin more preferably contains 80% by weight or more of a block copolymer in which both ends of polydimethylsiloxane are polyethylene, as shown in formula (6), and more preferably contains 90% by weight or more. In formula (6), d is preferably an integer of 3 or more, and more preferably 10 or more. In equations (4) to (6), n is preferably an integer of 100 or greater, and more preferably 150 or greater.

[0081] For obtaining the properties of a sealant film and for manufacturing a sealant film, it is preferable that the silylated polyolefin satisfies the following i) and ii), more preferably that it satisfies the following i) to iii), and even more preferably that it satisfies the following i) to iv). i) Density is 0.9 g / cm³ 3 More than 1.0g / cm 3 The range is as follows: ii) The melting point is between 100°C and 140°C. iii) The number-average molecular weight is between 1,000 and 20,000. iv) The copolymerization rate of the silicone is in the range of 1% by weight or more and 50% by weight or less.

[0082] The polypropylene content in the inner layer is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and also preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less.

[0083] The content of silylated polyolefin in the inner layer is preferably 3% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and also preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0084] The inner layer may contain resin materials other than polypropylene and silylated polyolefins. Examples of such resin materials include polyethylene, (meth)acrylic resin, vinyl resin, cellulose resin, polyamide, polyester, and ionomer resin.

[0085] The inner layer may contain additives. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, compatibilizers, pigments, and modifying resins.

[0086] In one embodiment, the inner layer may be surface-treated. This can improve, for example, the adhesion between the inner layer and other layers. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the inner layer.

[0087] The sealant film may have two or more inner layers. The number of inner layers is preferably two or more, more preferably three or more, preferably seven or fewer, and more preferably five or fewer.

[0088] The thickness of the inner layer is 0.5 μm or more, preferably 1 μm or more, more preferably 1.5 μm or more, and also 3 μm or less, preferably 2.5 μm or less, and more preferably 2 μm or less. When the sealant film has two or more inner layers, it is preferable that the total thickness of the inner layers is within the above range. A sealant film having an inner layer with a thickness equal to or greater than the lower limit has, for example, excellent strength, heat resistance, and recyclability. A sealant film having an inner layer with a thickness equal to or less than the upper limit has, for example, excellent processability.

[0089] Herein, we will explain why the sealant film of this disclosure has excellent slip resistance and suitability for low-temperature heat sealing. The sealant film of this disclosure contains a silylated polyolefin in its inner layer. This reduces the surface tension of the inner layer, making it easier for contents that come into contact with the inner layer to slide off. Therefore, the sealant film of this disclosure, in which the surface that comes into contact with the contents when used as a packaging container is composed of the above-mentioned inner layer, exhibits excellent sliding properties. However, it is also known that silylated resins are less suitable for heat sealing than unsilylated resins. In the sealant film of this disclosure, the thickness of the inner layer containing the silylated resin is below a certain level (e.g., 3 μm or less), so when heat sealing is performed with two sealant films facing each other, the inner layer is pushed aside, and the intermediate layer is exposed to the innermost surface of the sealant film. As a result, heat sealing is performed with the intermediate layers of the sealant films facing each other. It is known that the lower the density of the resin, the lower the melting point of the resin, and the density is below a certain level (e.g., 0.89 g / cm³). 3 The intermediate layer (described below) has a low melting point, and even at low temperatures, the intermediate layer melts and heat-seals itself to itself. In this way, the sealant film of the present disclosure exhibits excellent slip resistance and excellent low-temperature heat sealability.

[0090] [Laminated structure] The laminate of the present disclosure comprises a sealant film of the present disclosure and a substrate. In one embodiment, the sealant film is positioned such that the outer layer faces the substrate.

[0091] In one embodiment, the substrate is a polypropylene resin substrate containing polypropylene as the main component.

[0092] The laminate 1 shown in Figure 3 comprises a polypropylene resin substrate 20, an adhesive layer 30, and a sealant film 10 in that order. The sealant film 10 comprises an outer layer 12, an intermediate layer 13, and an inner layer 14 in that order. The laminate 1 shown in Figure 4 comprises a polypropylene resin substrate 20, an adhesive layer 30, another polypropylene resin substrate 20, another adhesive layer 30, and a sealant film 10, in that order. The sealant film 10 comprises an outer layer 12, an intermediate layer 13, and an inner layer 14, in that order.

[0093] In one embodiment, the laminate 1 further comprises a printed layer (not shown) on a polypropylene resin substrate 20. The printed layer is typically formed on the surface of the polypropylene resin substrate 20 facing the sealant film 10.

[0094] In one embodiment, by having polypropylene as the main component of both the resin constituting the polypropylene resin substrate and the resin constituting the sealant film, the recyclability of the laminate can be improved, for example.

[0095] The polypropylene content in the entire laminate of this disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and particularly preferably 90% by mass or more. Such a laminate can be used to produce, for example, monomaterial packaging containers, and the recyclability of the packaging containers can be improved. There is no particular upper limit to the polypropylene content, but it may be, for example, 99% by mass or 95% by mass. The polypropylene content in the laminate refers to the ratio of the polypropylene content to the sum of the resin material content in each layer constituting the laminate.

[0096] <Polypropylene resin base material> In one embodiment, the polypropylene resin substrate contains polypropylene as the main component, i.e., in an amount exceeding 50% by mass. A laminate comprising the polypropylene resin substrate exhibits excellent oil resistance, for example.

[0097] Polypropylene may be propylene homopolymer, propylene random copolymer, or propylene block copolymer, or a mixture of two or more selected from these. From the perspective of reducing environmental impact, biomass-derived polypropylene or mechanically or chemically recycled polypropylene may be used as the polypropylene. Further details are as described above.

[0098] Among polypropylenes, propylene homopolymer or propylene random copolymer is preferable from the viewpoint of transparency. When rigidity and heat resistance of the packaging container are important, propylene homopolymer is preferable. When impact resistance of the packaging container is important, propylene random copolymer is preferable.

[0099] From the viewpoint of film-forming properties and processability, the polypropylene MFR is preferably 0.1 g / 10 min or more, more preferably 0.2 g / 10 min or more, even more preferably 0.5 g / 10 min or more, preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, and even more preferably 10 g / 10 min or less.

[0100] The polypropylene resin substrate may contain resin materials other than polypropylene. Examples of such resin materials include polyethylene, (meth)acrylic resin, vinyl resin, cellulose resin, polyamide, polyester, and ionomer resin. The polypropylene resin substrate may contain the above-mentioned additives.

[0101] The polypropylene content in the polypropylene resin substrate is preferably more than 50% by mass, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Laminates comprising such a polypropylene resin substrate have excellent recyclability, for example.

[0102] In one embodiment, the polypropylene resin substrate is a substrate that has undergone a stretching treatment, i.e., a stretched substrate. Such a substrate has excellent properties such as strength, heat resistance, and transparency. The stretching treatment may be uniaxial stretching or biaxial stretching. When stretching in the mechanical direction (the flow direction of the substrate, MD direction), the stretching ratio is preferably 2 times or more, more preferably 3 times or more, preferably 10 times or less, and more preferably 7 times or less. When stretching in the width direction (the direction perpendicular to the MD direction, TD direction), the stretching ratio is preferably 2 times or more, more preferably 3 times or more, preferably 10 times or less, and more preferably 7 times or less. By setting the stretching ratio to 2 times or more, for example, the strength, heat resistance, and transparency of the substrate can be improved, and the printability of the substrate can also be improved. From the viewpoint of the breaking limit of the substrate, a stretching ratio of 10 times or less is preferable.

[0103] Polypropylene resin substrates can be produced, for example, by forming a film from polypropylene or a resin composition thereof using a T-die method or an inflation method, and then stretching the film. The inflation method allows for simultaneous film formation and stretching.

[0104] In one embodiment, the polypropylene resin substrate may be subjected to the above-mentioned surface treatment. This can improve, for example, the adhesion between the polypropylene resin substrate and other layers. An easy-adhesion layer may be provided on the surface of the polypropylene resin substrate.

[0105] The haze value of the polypropylene resin substrate is preferably 25% or less, more preferably 15% or less, and even more preferably 10% or less. A lower haze value is preferable, but for example, the lower limit may be 0.1% or 1%. The haze value of the substrate is measured in accordance with JIS K7136:2000.

[0106] The polypropylene resin substrate may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin substrate is preferably 5 μm or more, more preferably 8 μm or more, even more preferably 10 μm or more, preferably 300 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. Laminates having a polypropylene resin substrate with a thickness equal to or greater than the lower limit have, for example, excellent strength and heat resistance. Laminates having a polypropylene resin substrate with a thickness equal to or less than the upper limit have, for example, excellent processability.

[0107] <Print layer> The laminate of this disclosure may have a printed layer on the surface of a substrate such as a polypropylene resin substrate. Examples of images formed in the printed layer include characters, patterns, symbols, and combinations thereof. The printed layer may be formed using, for example, biomass-derived ink. This can, for example, further reduce the environmental impact.

[0108] Conventional printing methods such as gravure printing, offset printing, and flexographic printing can be used to form the printed layer. Among these, flexographic printing is preferred from the viewpoint of reducing environmental impact.

[0109] The printed layer may be formed on any surface of the polypropylene resin substrate. Preferably, the printed layer is formed on the sealant film side of the polypropylene resin substrate, as this suppresses contact between the printed layer and the outside air and inhibits deterioration of the printed layer over time.

[0110] <Adhesive layer> The laminate of this disclosure may have adhesive layers between any of the layers, such as between the substrate and the sealant film, between two polypropylene resin substrates, or between the polypropylene resin substrate and the sealant film. Such a laminate has excellent interlayer adhesion, for example.

[0111] The adhesive layer is composed of, for example, an adhesive, which may be a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive. The adhesive may be solvent-free or solvent-based. Examples of adhesives include polyether-based adhesives, polyester-based adhesives, polyurethane-based adhesives, silicone-based adhesives, epoxy-based adhesives, rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, and phenol-based adhesives. Among these, polyurethane-based adhesives are preferred, and two-component curing polyurethane-based adhesives are more preferred.

[0112] The thickness of the adhesive layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.5 μm or more, particularly preferably 0.8 μm or more, preferably 10 μm or less, more preferably 8 μm or less, even more preferably 6 μm or less, and particularly preferably 5 μm or less.

[0113] The adhesive layer can be formed by applying an adhesive to an object using conventionally known methods such as the direct gravure roll coating method, gravure roll coating method, kiss coating method, reverse roll coating method, fontein method, and transfer roll coating method, and drying as desired. The laminate of this disclosure may be manufactured by laminating a substrate and a sealant film, or a polypropylene resin substrate and a polypropylene resin substrate and a sealant film, using a non-solvent lamination method with a solvent-free adhesive, or by laminating them using a dry lamination method with a solvent-type adhesive.

[0114] [Packaging container] The laminate of this disclosure can be suitably used as a packaging material. The packaging material is used to manufacture a packaging container. The packaging material comprises the laminate of this disclosure. A packaging container can be manufactured by using at least a packaging material comprising the laminate of this disclosure.

[0115] The packaging containers of this disclosure comprise the laminates of this disclosure. Examples of packaging containers include packaging bags, tube containers, and containers with lids. A container with a lid comprises a container body having a storage compartment and a lid material joined (heat-sealed) to the container body to seal the storage compartment.

[0116] The packaging container has a heat-sealed section. Examples of heat-sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high-frequency sealing, and ultrasonic sealing.

[0117] Examples of packaging bags include various types such as standing pouches, side-sealed bags, two-sided sealed bags, three-sided sealed bags, four-sided sealed bags, envelope-type sealed bags, gusset-type sealed bags (pillow seals), pleated sealed bags, flat-bottom sealed bags, square-bottom sealed bags, and gusseted bags. Specific examples of packaging bags include small bags and standing pouches. Packaging containers may be equipped with an easy-open section. Examples of an easy-open section include a notch that serves as the starting point for tearing the packaging container, and a half-cut line formed by laser processing or a cutter as a path for tearing the packaging container.

[0118] Examples of contents that can be contained in a packaging container include liquids, solids, powders, and gels. The contents may be food or beverages, or non-food items such as chemicals, cosmetics, pharmaceuticals, metal parts, and electronic components. Specifically, the contents may include sauces, soy sauce, dressings, ketchup, syrups, cooking alcoholic beverages, edible oils, mayonnaise, and other liquid or viscous condiments; liquid soups, powdered soups, fruit juices; spices; liquid beverages, jelly beverages, instant foods, and other food and beverages; shampoos, rinses, conditioners, hand soaps, body soaps, fragrances, deodorizers, insect repellents, detergents; creams; metal parts, and electronic components. After the contents are placed in the packaging container, the opening of the packaging container can be sealed by heat sealing.

[0119] In one embodiment, a packaging bag can be made by folding the laminate of the present disclosure in half so that the base material is on the outside and the sealant film is on the inside, overlapping the two halves, and then heat-sealing the edges. In another embodiment, a packaging bag can be made by overlapping multiple laminates of the present disclosure so that the sealant films face each other, and then heat-sealing the edges. The entire packaging bag may be made of the above laminate, or only a part of the packaging bag may be made of the above laminate. Figure 5 shows an example of a packaging bag. In the figure, the shaded area represents the heat-sealed portion.

[0120] In one embodiment, the laminate of the present disclosure is used as a lid material in a container with a lid. The container with a lid comprises a container body having a storage compartment and a lid material joined (heat-sealed) to the container body so as to seal the storage compartment. Here, the lid material, i.e., the sealant film of the laminate, and the container body are heat-sealed. Examples of container body shapes include cup shape and bottomed cylindrical shape. The container body is made of, for example, polystyrene, polypropylene, polyethylene, or paper.

[0121] In one embodiment, the standing pouch comprises a body (side sheet) and a bottom (bottom sheet). The side sheet and the bottom sheet may be made of the same material or of different materials. The bottom sheet maintains the shape of the side sheet, thereby providing the pouch with self-supporting properties and enabling it to be a standing pouch. A storage space for containing contents is formed within the area enclosed by the side sheet and the bottom sheet. In the standing pouch, only the body may be made of the laminate of the disclosure, only the bottom may be made of the laminate of the disclosure, or both the body and the bottom may be made of the laminate of the disclosure.

[0122] In one embodiment, the side sheet can be formed by making a bag such that the sealant film of the laminate of the present disclosure is the innermost layer. In one embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them so that the sealant films face each other, and heat-sealing the side edges on both sides to form a bag.

[0123] In another embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them so that the sealant films face each other, inserting two V-shaped folded laminates with the sealant films facing outwards into the gaps between the laminates at the side edges on both sides of the overlapped laminates, and then heat-sealing them. According to this manufacturing method, a standing pouch having a body with side gussets can be obtained. An example of a standing pouch is shown in Figure 6. In the figure, the shaded area represents the heat-sealed portion.

[0124] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower parts of the bag-formed side sheets and heat sealing. More specifically, the bottom sheet can be formed by inserting a laminate folded in a V-shape with the sealant film on the outside between the lower parts of the bag-formed side sheets and heat sealing.

[0125] In one embodiment, two of the above-mentioned laminates are prepared and stacked so that the sealant films face each other. Then, the other laminate is folded into a V-shape so that the sealant film faces outwards, and this is sandwiched between the bottoms of the stacked laminates and heat-sealed to form the bottom. Next, the two sides adjacent to the bottom are heat-sealed to form the body. In this way, a standing pouch of one embodiment can be formed. [Examples]

[0126] The sealant films of this disclosure will be described in detail below based on examples, but the sealant films of this disclosure are not limited to the examples.

[0127] The various raw materials used in the following examples and comparative examples are as follows: · Resin A Propylene Random Copolymer Product name: Cosmoplane FL7540, manufactured by TPC Corporation Density: 0.900g / cm 3 Melting point: 138℃, MFR: 7g / 10min ·Resin B Propylene homopolymer Product name: Cosmoplane FL7013, manufactured by TPC Corporation Density: 0.900g / cm 3 Melting point: 165℃, MFR: 7g / 10min ·Resin C Propylene-based elastomer Propylene-ethylene copolymer, ethylene unit content: 16% by mass Product name: Vistamaxx(registered trademark) 6102, manufactured by ExxonMobil. Density: 0.862g / cm 3 MFR: 3.0g / 10 minutes ·Resin D Composition of 70% by mass of polypropylene and 30% by mass of silylated polyolefin Product name: Exfora (registered trademark) PP2000, manufactured by Mitsui Chemicals Fine, Inc. Density: 0.917g / cm 3 Melting point: 125℃ and 160℃, MFR: 20g / 10min

[0128] [Example 1] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin B, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (17 μm), an intermediate layer (5 μm), and an inner layer (1 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Example 1 is 0.87 g / cm³. 3 That was the case.

[0129] [Example 2] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin B, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (16 μm), an intermediate layer (5 μm), and an inner layer (2 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Example 2 is 0.87 g / cm³. 3 That was the case.

[0130] [Example 3] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin B, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (15 μm), an intermediate layer (5 μm), and an inner layer (3 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Example 3 is 0.87 g / cm³. 3 That was the case.

[0131] [Example 4] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin A, resin A, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (17 μm), an intermediate layer (5 μm), and an inner layer (1 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Example 4 is 0.87 g / cm³. 3 That was the case.

[0132] [Example 5] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin B, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (17.5 μm), an intermediate layer (5 μm), and an inner layer (0.5 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Example 5 is 0.87 g / cm³. 3 That was the case.

[0133] [Comparative Example 1] A sealant film with a total thickness of 30 μm was fabricated by extruding five layers of resin A, resin A, resin B, resin A, and resin A using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (17 μm), an intermediate layer (5 μm), and an inner layer (1 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Comparative Example 1 was 0.90 g / cm³. 3 That was the case.

[0134] [Comparative Example 2] A sealant film with a total thickness of 30 μm was prepared by extruding four layers of resin A, resin B, and a resin composition of 30% by mass of resin A and 70% by mass of resin C using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (18 μm), an intermediate layer (5 μm), and an inner layer (1 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Comparative Example 2 was 0.87 g / cm³. 3 That was the case.

[0135] [Comparative Example 3] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin B, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (13 μm), an intermediate layer (5 μm), and an inner layer (5 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Comparative Example 3 was 0.87 g / cm³. 3 That was the case.

[0136] [Comparative Example 4] A sealant film with a total thickness of 30 μm was prepared by extruding five layers of resin A, resin B, a resin composition of 30% by mass of resin A and 70% by mass of resin C, and resin D using a casting method. The layers consist of a first layer (2 μm), a second layer (5 μm), a third layer (17.6 μm), an intermediate layer (5 μm), and an inner layer (0.4 μm). The numbers in parentheses indicate the thickness of each layer. The density of the intermediate layer in the sealant film of Comparative Example 4 was 0.87 g / cm³. 3 That was the case.

[0137] [Fabrication of laminates] A 20 μm thick biaxially oriented polypropylene film (manufactured by Toyobo Co., Ltd., product name: P2171) was prepared, with one side treated with corona discharge. A printed layer was formed on the corona discharge-treated side of the biaxially oriented polypropylene film using a solvent-based gravure ink (manufactured by DIC Graphics, Inc., Finart) by gravure printing. Laminates of Examples 1-5 and Comparative Examples 1-4 were prepared by bonding the first layer of the sealant film of Examples 1-5 and Comparative Examples 1-4 to the printed layer via a 3.5 μm thick adhesive layer made of a two-component curing polyurethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) so that the first layer of the sealant film of Examples 1-5 and Comparative Examples 1-4 faced the printed layer.

[0138] [Evaluation of heat seal start temperature] Two laminates each of Examples 1-5 and Comparative Examples 1-4 were prepared. The inner layers of the two laminates were placed facing each other and heat-sealed at 100°C for 1 second. A 15mm wide test specimen was cut from the heat-sealed portion, and its peel strength was measured in accordance with JIS Z1707:2019. The Tensilon universal material tester RTC-1530 was used to measure the peel strength of the 15mm wide specimen under measurement conditions of a tensile speed of 300mm / min. Measurements were performed on 5 test specimens (N=5), and the average value obtained was taken as the peel strength. The peel strength was similarly measured when the heat sealing temperature was set to 110°C, 120°C, 130°C, 140°C, and 150°C. The lowest heat seal temperature at which a peel strength of 20 N / 15 mm or higher was measured was defined as the heat seal start temperature. A lower heat seal start temperature indicates better low-temperature heat sealability and allows for filling of contents even at high speeds. The results are shown in Table 1.

[0139] [Evaluation of slipperiness] Three laminates each were prepared for Examples 1-5 and Comparative Examples 1-4. Two laminates were stacked so that their inner layers faced each other, and the two sides were heat-sealed to form a body with a side seal (right) and a side seal (left). Next, the remaining laminate was folded into a V-shape so that its inner layer faced outward, sandwiched from one end of the body, and heat-sealed to form a bottom (bottom) with a bottom seal (front) and a bottom seal (back). In this way, a standing pouch was manufactured. The heat sealing conditions were a temperature of 140°C and a pressure of 1 kgf / cm². 2 , set to 1 second. A standing pouch was filled with 10g of flour through the top opening. The standing pouch was tilted at a 135° angle, and the time it took for 90% of the filled flour to be released from the pouch was measured. The criteria for evaluating the slipperiness were as follows. The results are shown in Table 1. A: Less than 30 seconds B: 30 seconds to 1 minute C: More than 1 minute

[0140] [Table 1]

[0141] As is clear from Table 1 above, the sealant films of Examples 1 to 5 had a low heat-sealing start temperature of 100 to 120°C, exhibiting excellent low-temperature heat-sealing properties as well as excellent slip resistance. Furthermore, the sealant films of Examples 1 to 5 contained polypropylene as the main component and exhibited excellent recyclability. Furthermore, the sealant film of Comparative Example 4, which had an inner layer thickness of less than 0.5 μm, exhibited poor sliding properties. This is thought to be because the inner layer was too thin to form a uniform film, resulting in holes and exposure of the intermediate layer. [Explanation of Symbols]

[0142] 1: Laminate 10: Sealant film 12:Outer layer 12a: 1st layer 12b: 2nd layer 12c: 3rd layer 13: Middle Class 14: Inner layer 20: Polypropylene resin base material 30: Adhesive layer

Claims

1. A sealant film comprising an outer layer, an intermediate layer, and an inner layer in this order, The inner layer constitutes one surface of the sealant film. The outer layer contains polypropylene as its main component, The aforementioned intermediate layer contains polypropylene and a propylene-based elastomer. The density of the aforementioned intermediate layer is 0.85 g / cm³. ３ 0.89g / cm or more ３ The following: The inner layer contains polypropylene and silylated polyolefin, A sealant film in which the thickness of the inner layer is 0.5 μm or more and 3 μm or less.

2. The sealant film according to claim 1, wherein the propylene-based elastomer is a propylene-ethylene copolymer.

3. The sealant film according to claim 1 or 2, wherein the content of α-olefin units relative to all constituent units of the propylene-based elastomer is 3% by mass or more and 20% by mass or less.

4. The sealant film according to claim 1 or 2, wherein the content of the propylene-based elastomer in the intermediate layer is 30% by mass or more and 95% by mass or less.

5. The sealant film according to claim 1 or 2, wherein the silylated polyolefin is a reaction product of a silicon-containing compound having two or more SiH groups in its molecule and a vinyl group-containing compound having a vinyl group at the end of the polymer of the olefin.

6. The sealant film according to claim 1 or 2, wherein the content of the silylated polyolefin in the inner layer is 3% by mass or more and 30% by mass or less.

7. The outer layer comprises a first layer, a second layer, and a third layer in this order. The first layer contains propylene random copolymer as its main component, The second layer contains propylene random copolymer as its main component, The sealant film according to claim 1 or 2, wherein the third layer contains a propylene homopolymer as a main component.

8. A laminate comprising a sealant film and a substrate according to claim 1 or 2.

9. The laminate according to claim 8, wherein the substrate is a polypropylene resin substrate containing polypropylene as the main component.

10. A packaging material comprising the laminate described in claim 8.

11. A packaging container using the packaging material described in claim 10.

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