Laminated films and containers

Abstract

Provided is a laminate film which can be easily removed during a crushing step performed by hand or machine but which does not readily peel away during ordinary use.　This laminate film (10) has a substrate layer (1) and a breakable layer (3) in the order given. The substrate layer contains an olefinic resin, and the breakable layer contains the olefinic resin, a resin that is immiscible with the olefinic resin, and particles.

Description

[Technical Field] 【0001】 This invention relates to laminated films and containers. [Background technology] 【0002】 Conventionally, laminated films with a heat-seal layer have been used as in-mold labels. In-mold labels are set in a mold used to form containers and adhere to the surface of the container due to the heat generated during molding. Because the label is adhered simultaneously with the molding of the container, it is characterized by the fact that the label becomes almost integrated with the container, giving it the appearance of being printed directly onto the container. 【0003】 In-mold labels have their adhesive strength adjusted to prevent them from peeling off during normal use, such as during storage or transport of the container (see, for example, Patent Document 1). On the other hand, in-mold labels have also been proposed that have a release portion with weaker adhesive strength to serve as a gripping area when peeling the label from the container (see, for example, Patent Document 2). [Prior art documents] [Patent Documents] 【0004】 [Patent Document 1] Japanese Patent Publication No. 2002-258752 [Patent Document 2] Japanese Patent Publication No. 2004-264825 [Overview of the Initiative] [Problems that the invention aims to solve] 【0005】 In recent years, from an environmental protection standpoint, plastic containers are increasingly being recycled. Containers are sometimes melted down and recycled into plastic materials such as pellets. However, if, for example, the container is made of polyethylene terephthalate and the laminated film is made of polypropylene, recycling the labeled container as is would result in a significant amount of foreign material contamination in the recycled product. 【0006】 Furthermore, laminated films are often printed with labels. When containers with labels are recycled, the ink in the laminated film can cause discoloration in recycled products such as pellets. Not only the ink, but also additives such as adhesives and coatings in the laminated film can degrade when heated during the manufacturing of recycled products, causing discoloration in the recycled products. 【0007】 Therefore, it is necessary to remove the labels from labeled containers, but the laminated film, which is bonded via a heat-seal layer, adheres strongly to the surface of the container. As a result, it is difficult to peel off the entire film by hand, and even if it is peeled off, some of it remains on the container. Because it is difficult to recycle labeled containers as raw materials for the resin of the container as described above, labeled containers have mostly been incinerated as fuel. 【0008】 The present invention aims to provide a laminated film that can be easily peeled off during manual or mechanical crushing processes, but is difficult to peel off under normal use conditions. [Means for solving the problem] 【0009】 As a result of diligent research by the inventors to solve the above problems, they found that the above problems can be solved by providing an easily breakable layer between the heat-seal layer that adheres to the container and the base material layer, and by incorporating multiple mutually immiscible resins into the easily breakable layer, thereby making it easier for layer shearing (cohesive failure) to occur within the easily breakable layer, and thus completed the present invention. In other words, the present invention is as follows. 【0010】 [1] A laminated film having a base layer and an easily breakable layer in this order, The aforementioned substrate layer contains an olefin resin, The easily fractured layer contains the olefin resin, a resin incompatible with the olefin resin, and particles, wherein the particles have an average particle diameter of 3 to 20 μm, and the amount of particles is 15 parts by mass or less relative to the total resin components in the easily fractured layer, and the void ratio of the easily fractured layer is 10% or less. Laminated film. 【0011】 [2] A laminated film having a heat-sealing layer on the surface opposite to the base material layer of the easily breakable layer, The heat-sealing layer contains a resin having a lower melting point than the olefin resin. The laminated film according to [1] above. 【0012】 [3] The particle size distribution D90 / D10 of the particles in the easily breakable layer is 1 to 5. The laminated film according to [1] above. 【0013】 [4] The easily breakable layer is a stretched film. The laminated film according to [1] above. 【0014】 [5] The heat-sealing layer further contains a lubricant. The laminated film according to [1] above. 【0015】 [6] The surface of the base material layer opposite to the heat-sealing layer further includes a coating layer for printing. The laminated film according to [1] above. 【0016】 [7] The peel strength of the easily breakable layer is 100 to 300 gf / 15 mm. The laminated film according to [1] above. 【0017】 [8] A container in which the laminated film according to any one of [1] to [7] above is attached to a resin container body. 【Advantages of the Invention】[[ID=第43]] 【0018】 According to the present invention, it is possible to provide a laminated film that can be easily peeled off in a crushing process by hand or machine, but is difficult to peel off under normal use conditions. 【Brief Description of the Drawings】 【0019】 [Figure 1] It is a cross-sectional view showing an example of the laminated film. [[ID=ID=57]] [Modes for carrying out the invention] 【0020】 The laminated film of the present invention and the container to which the laminated film is attached will be described in detail below. The following is an example or representative example of the present invention, and the present invention is not limited thereto. Furthermore, in the following explanation, "easily breakable layer" refers to a resin layer that can be easily peeled off during crushing processes by hand or machine, but which has sufficient peelability to resist peeling under normal use conditions. The main component refers to a component that makes up 50% by weight or more of the layer, preferably 70% by mass. 【0021】 [Laminated film] The laminated film of the present invention is a laminate of thermoplastic films having a base layer, an easily breakable layer, and a heat-seal layer in that order. The base layer contains, for example, a thermoplastic resin such as an olefin resin. The easily breakable layer contains, for example, a thermoplastic resin such as an olefin resin, a resin that is incompatible with the olefin resin, and particles. The particles of the easily breakable layer have an average particle diameter of 3 to 20 μm and are preferably blended in an amount of 15 parts by mass or less relative to the total resin components of the easily breakable layer. The void ratio of the easily breakable layer is preferably 10% or less. The heat-seal layer contains, for example, a resin with a lower melting point than the olefin resin. The smoothness of the heat-seal layer is, for example, 50 to 200 s. 【0022】 The laminated film of the present invention can be bonded to a container via a heat-seal layer. While not particularly limited, it can be used, for example, as an in-mold label applied during the molding of ethylene-based resin containers. It can also be used as a security label to prevent counterfeiting. 【0023】 Generally, when used as an in-mold label, the laminated film is placed inside the mold used to form the container and adheres to the surface of the container via a heat-seal layer that melts due to the heat generated during molding. In this way, the laminated film adheres to the container as if it were an integral part of it, and its adhesive strength is high, making it difficult to peel off the label by hand. If you try to forcibly peel it off, the label will break and remain on the container. 【0024】 However, the laminated film of the present invention has an easily breakable layer between the base layer and the heat-seal layer. By blending multiple resins and particles in this easily breakable layer, incompatible resins within the layer cause shearing, making it prone to cohesive failure. As a result, the in-mold label can be easily peeled off the container during recycling. 【0025】 Furthermore, the particles in the easily breakable layer have a predetermined average particle size, and are contained in a constant proportion. This has the effect of improving air release during in-mold molding (preventing blistering) and controlling variations in peelability from product to product. 【0026】 Furthermore, after peeling the laminated film from the container, the heat-seal layer remains on the container side. Here, if a portion of the heat-seal layer contains the same material as the resin container, for example, if both the heat-seal layer and the resin container contain ethylene-based resin, the heat-seal layer can be recycled together with the container. Also, if the base layer is made of a different material from the container and may contain various additives, it can be separated from the container along with the easily breakable layer, making it easy to recycle the container as its resin material. Moreover, if a printing coating layer is formed on the surface of the base layer opposite the heat-seal layer, the coating layer can also be removed from the container along with the easily breakable layer. 【0027】 On the other hand, it is also necessary that the laminated film has properties that prevent the label from peeling off easily, not only from the viewpoint of release properties, but also under normal use conditions such as storage, transportation, and printing. For this reason, in the present invention, from the viewpoint of interlayer adhesion (compatibility), it is preferable to contain a specific olefin resin in the base layer and the easily breakable layer. Furthermore, from the viewpoint of compatibility, it is preferable that the easily breakable layer further contains a predetermined elastomer. Furthermore, from the viewpoint of compatibility, it is preferable that the heat seal layer contains a specific olefin elastomer. By containing materials that are compatible with each other in each layer, the interlayer adhesion between the base layer and the easily breakable layer, and between the easily breakable layer and the heat seal layer is increased to a certain extent, and the label can be made less likely to peel off under normal use conditions. 【0028】 Furthermore, the heat seal layer contains a resin with a lower melting point than the olefin resin selected for the base layer and the easily breakable layer, in relation to the other layers of the laminated film, from the viewpoint of heat sealability. In addition, the smoothness of the heat seal layer is adjusted to a predetermined range from the viewpoint of preventing blocking and blistering. 【0029】 Furthermore, the laminated film of the present invention can be used on substrates other than containers, provided that they can be heat-sealed. In this case, from the viewpoint of recycling the substrate, it is preferable that the material of the substrate consists of the same components as some of the components of the heat-seal layer. For example, the material of the substrate is an ethylene-based resin. 【0030】 Here, Figure 1 is a cross-sectional view showing an example of a laminated film. The laminated film 10 illustrated in Figure 1 comprises a base layer 1, a heat-seal layer 2 on one surface of the base layer 1, and an easily breakable layer 3 between the base layer and the heat-seal layer 2. If printing is to be applied to the surface of the base layer 1 opposite to the heat-seal layer 2, a coating layer 4 may be provided for printing characters, patterns, etc. The following explains each layer. 【0031】 (1. Base material layer) The base layer functions as a support for the laminated film. The base layer is preferably a resin film, from the viewpoint of imparting the desired rigidity or stiffness to the laminated film, and further providing water resistance. Olefin resins are preferred as the resin that can be used for the base layer because they exhibit excellent mechanical strength. 【0032】 <Olefin resin> Specific examples of olefin resins include polypropylene, polyethylene, or polymethyl-1-pentene. 【0033】 Among these, the base layer is preferably a resin film containing polypropylene as the main component. Polypropylene not only has excellent mechanical strength, but also enhances interlayer adhesion or compatibility with the same or similar olefin resin (e.g., polypropylene) contained in adjacent easily breakable layers. Therefore, when peeling the label from the container, cohesive fracture between the easily breakable layers takes precedence over interfacial fracture between the base layer and the easily breakable layers. Thus, the mixing of foreign materials caused by interfacial fracture during recycling can be avoided. 【0034】 <<Polypropylene>> Polypropylene is not particularly limited as long as propylene is used as the main monomer. For example, isotactic polymers or syndiotactic polymers obtained by homopolymerizing propylene can be used. Alternatively, propylene-α-olefin copolymers, which are copolymers of propylene as the main component with α-olefins such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene, can also be used. The copolymer may have a binary system or a multi-component system of ternary or more monomer components, and may be a random copolymer or a block copolymer. Furthermore, a propylene homopolymer and a propylene copolymer may be used in combination. 【0035】 As for polypropylene, graft-modified versions can be used as needed from the viewpoint of improving adhesion or moldability between the film and adjacent layers. Known methods can be used for graft modification. Specifically, graft-modified products using unsaturated carboxylic acids or their derivatives as graft monomers can be mentioned. Examples of the above unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, or citraconic acid. Examples of the above unsaturated carboxylic acids include acid anhydrides, esters, amidates, imides, or metal salts of the above unsaturated carboxylic acids. 【0036】 Specific examples of graft monomers include maleic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, ethyl acrylate, or acrylamide. 【0037】 The graft monomer can typically be used in an amount of 0.005 to 10% by mass, preferably 0.01 to 5% by mass, relative to polypropylene. 【0038】 For the base layer, one type of polypropylene from the above may be used alone, or two or more types may be used in combination. From the viewpoint of moldability, mechanical strength, and cost, propylene homopolymer is preferred as the main component of the base layer because it is easy to handle. 【0039】 The base layer may be a film using only polypropylene as the thermoplastic resin, or it may contain thermoplastic resins other than polypropylene to the extent that they do not impair the effects of the present invention. Examples of thermoplastic resins that can be used in combination include ethylene-based resins such as high-density polyethylene, medium-density polyethylene, and linear low-density polyethylene; polyamide-based resins such as nylon-6 and nylon-6,6; thermoplastic polyester-based resins such as polyethylene terephthalate or its copolymer, polybutylene terephthalate, polybutylene succinate, or polylactic acid; polycarbonate; and styrene-based resins such as atactic polystyrene or syndiotactic polystyrene. 【0040】 <Filler> The substrate layer may further contain fillers. The inclusion of fillers facilitates adjustment of the whiteness or opacity of the substrate layer. Examples of usable fillers include inorganic fillers and organic fillers. 【0041】 The base layer is preferably a porous stretched film in which voids are formed inside with the filler as a nucleus by stretching a film containing a filler. During in-mold molding, the heat seal layer melts due to the heat transmitted from the mold, but if the laminated film is porous, the heat insulation is enhanced, resulting in less heat loss and allowing the heat seal layer to melt efficiently and sufficiently. Furthermore, the porous nature of the base layer allows for weight reduction of the laminated film. 【0042】 <<Inorganic filler>> As inorganic fillers, inorganic particles such as calcium carbonate, calcined clay, silica, diatomaceous earth, white clay, talc, titanium dioxide, barium sulfate, barium titanate, alumina, zeolite, mica, or glass fiber can be used, and among these, calcium carbonate is preferred due to its low cost, ease of availability, and minimal adverse effect on the resin. The average particle size of the inorganic filler, as measured by a particle size distribution analyzer using laser diffraction, is usually 0.01 to 15 μm, and preferably 0.1 to 5 μm. 【0043】 The inorganic and organic fillers mentioned above can be used individually or in combination as fillers. From the viewpoint of creating a porous structure, the filler content in the substrate layer (the total amount when inorganic and organic fillers are used in combination) is preferably 10% by mass or more, preferably 15% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less. 【0044】 <Other ingredients> The substrate layer may further contain additives such as heat stabilizers (antioxidants), light stabilizers, dispersants, lubricants, or nucleating agents, as needed. As a heat stabilizer, for example, sterically hindered phenolic antioxidants, phosphorus-based antioxidants, or amine-based antioxidants can be used, usually in a range of 0.001 to 1% by mass. As a light stabilizer, for example, sterically hindered amine-based light stabilizers, benzotriazole-based light stabilizers, or benzophenone-based light stabilizers can be used, usually in a range of 0.001 to 1% by mass. Examples of dispersants or lubricants include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, or salts thereof. These can typically be used in amounts ranging from 0.01% to 4% by mass, for example, to disperse fillers. 【0045】 <Layer configuration> The base layer may be a single layer or a multilayer structure of two or three or more layers. Multilayering makes it possible to impart various functions to the base layer, such as mechanical properties, writing properties, abrasion resistance, or suitability for secondary processing. 【0046】 The base layer preferably includes a stretched film stretched in at least one axial direction, and more preferably includes a porous stretched film having internal voids due to stretching. The base layer including the stretched film has high dimensional stability and mechanical strength, and excellent thickness uniformity, so a laminated film with excellent post-processing properties can be obtained. If the base material layer has a multilayer structure, the number of stretching axes for each layer may be 1 axis / 1 axis, 1 axis / 2 axes, 2 axes / 1 axis, 1 axis / 1 axis / 2 axes, 1 axis / 2 axes / 1 axis, 2 axes / 1 axis / 1 axis, 1 axis / 2 axes / 2 axes, 2 axes / 2 axes / 1 axis, or 2 axes / 2 axes / 2 axes. 【0047】 <Porosity> From the viewpoint of reducing weight or whitening, the porosity of the base layer is preferably 10% or more. From the viewpoint of maintaining strength, the porosity is preferably 60% or less, and more preferably 40% or less. The above porosity can be determined from the ratio of the area occupied by voids in a certain region of the cross-section of the film observed with an electron microscope. 【0048】 (Heat seal layer) The heat-seal layer imparts heat-sealability to the laminated film. The laminated film can be bonded to a container via the heat-seal layer. In addition to the low-melting-point resin, which is the main component that provides heat-sealing properties, the heat-seal layer may further contain an olefin-based elastomer from the viewpoint of interlayer adhesion with the easily fractured layer and from the viewpoint of providing strength. Furthermore, it is preferable to further contain a lubricant from the viewpoint of preventing blocking. Each component is described below. 【0049】 The main component of the heat seal layer is not particularly limited as long as it can provide heat sealability, but it is preferable to use a low-melting-point resin which has a lower melting point than the olefin resin contained in the base layer and the easily fractured layer, and also from the viewpoint of facilitating heat sealing. The low-melting-point resin is a thermoplastic resin having a melting point of 135°C or lower. Preferably, the melting point of the low-melting-point resin is 120°C or lower. If the melting point is 135°C or lower, it is easy to bond with sufficient strength even at low molding temperatures. From the viewpoint of suppressing the softening of the heat seal layer under high-temperature conditions in summer and preventing blocking between in-mold labels during storage, it is preferable that the melting point of the low-melting-point resin be 60°C or higher. 【0050】 While there are no particular limitations on the low-melting-point resins that can be used as long as their melting point is 135°C or lower, specific examples include homopolymers of olefins such as ethylene, propylene, butene, pentene, hexene, methylpentene, or octene; copolymers of two or more of these olefins; copolymers of one or more of these olefins with one or more comonomers copolymerizable with olefins; or metal salts thereof. Examples of comonomers copolymerizable with olefins include styrenes such as styrene and α-methylstyrene; vinyl carboxylates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl laurate, vinyl stearate, vinyl benzoate, or butyl benzoate; and acrylic acids such as acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, or acrylonitrile. 【0051】 From the viewpoint of adhesion to resin containers, among the above, olefin resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, or metallocene catalyst-based polyolefins such as metallocene catalyst-based polypropylene are preferred. From the viewpoint of low melting point and good moldability, low-density polyethylene is more preferred. 【0052】 <Low-density polyethylene (LDPE)> Low-density polyethylene (LDPE), which is used as the main component of the heat seal layer, has a density (g / cm³). 3 The ratio is 0.900 or higher and less than 0.935, and the tensile impact strength is 250 kJ / m 2 The density is as follows: 0.930 g / cm³ 3 The following is preferable: 0.925 g / cm³ 3 The following is more preferable: The tensile impact strength is measured in accordance with JIS K6922-2, and preferably has an upper limit of 230 kJ / m 2 More preferably, 220 kJ / m 2 The following applies, while the lower limit is typically 100 kJ / m³. 2 The above is preferable, preferably 150 kJ / m³ 2 More preferably 180 kJ / m³2 The above is the case. Examples of the low-density polyethylene include high-pressure low-density polyethylene produced by the high-pressure method, and low-pressure low-density polyethylene produced by the low-pressure method using a Ziegler-Natta catalyst. 【0053】 <Olefin-based elastomer> The heat-sealing layer preferably contains an olefin-based elastomer from the viewpoints of interlayer adhesion with the easily destructible layer and imparting strength. The olefin-based elastomer in the heat-sealing layer has fluidity (plasticity) at high temperatures and rubber-like elasticity (elastomer) at normal temperatures, and means a polymer material having a hard segment component made of polyolefins such as polyethylene and polypropylene, and a soft segment component made of another polyolefin, an α-olefin such as 1-butene, 1-hexene, 1-heptene, 4-methyl-1-pentene, or an ethylene-propylene rubber. Known olefin-based elastomers include random copolymers, block copolymers, blends, dynamically crosslinked bodies, or sea-island dispersions, etc., and the types thereof are not particularly limited. The olefin-based elastomer may be a binary system or a multi-component system of ternary or higher. Also, two or more olefin-based elastomers having different compositions can be mixed and used. 【0054】 Various known olefin-based elastomers can be used and are not particularly limited. Among these, random copolymers and block copolymers are preferred, and olefin-based elastomers (R-TPO), which are so-called reactor-made random copolymers and block copolymers, are more preferred. Among these, olefin-based elastomers (R-TPO) that are random copolymers are even more preferred, and metallocene catalyst-based polypropylene-based elastomers (R-TPO) copolymerized using a metallocene catalyst are particularly preferred. 【0055】 The modulus of elasticity of the olefin-based elastomer is preferably 100 MPa or less, more preferably 50 MPa or less, and even more preferably 20 MPa or less. If the modulus of elasticity is below the above upper limit, sufficient interlaminar adhesion with the easily fractured layer can be easily obtained, and sufficient strength can be imparted. The lower limit of the above modulus of elasticity is not particularly limited, but is usually 0.1 MPa or more, and is preferably 0.5 MPa or more from the viewpoint of suppressing excessive tackiness. 【0056】 The above modulus of elasticity is measured as follows. Olefin elastomer is formed into a 500 μm thick sheet using a hydraulic press, and this is cut into 30 mm x 15 mm sections to prepare test specimens. Dynamic viscoelasticity measurements of these test specimens are performed using a solid viscoelasticity analyzer (RSA-III, manufactured by T.A. Instruments Japan). The measurement conditions are: chuck distance 20 mm, measurement frequency 10 Hz, strain 0.1%, heating rate 10 °C / min, tensile mode, and the storage modulus in the TD direction (vertical direction) at 23 °C is determined as the modulus. 【0057】 <Lubricant> The heat seal layer preferably contains a lubricant from the viewpoint of preventing blocking. Examples of lubricants include higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, or salts thereof. Among these, higher fatty acids such as oleic acid and stearic acid are preferred, and ethylenebisoleamide (EBOA) is particularly preferred. 【0058】 Furthermore, by adjusting the smoothness of the heat-seal layer's surface and creating an air channel between the container and the heat-seal layer during in-mold molding, the occurrence of blisters can be reduced through this channel. 【0059】 (Easily Destroyable Layer) The easily breakable layer provides the laminated film with peelability that allows it to be easily peeled off during manual or mechanical crushing processes, while also providing adhesion that makes it difficult to peel off under normal use conditions. The easily breakable layer contains a thermoplastic resin such as an olefin resin, a resin that is incompatible with the olefin resin, and particles. The particles of the easily breakable layer have an average particle size of 3 to 20 μm and are preferably blended in an amount of 15 parts by mass or less relative to the total resin components of the easily breakable layer. The void ratio of the easily breakable layer is preferably 10% or less, and more preferably 5% or less. This is because if there are fewer voids, handling difficulties such as the voids being crushed and the label changing its properties when the label is heat-pressed onto the bottle are less likely to occur. Furthermore, the peel strength of the easily breakable layer is preferably 100 to 300 gf / 15 mm. In addition, from the viewpoint of providing compatibility (interlayer adhesion), for example, the easily breakable layer preferably contains a styrene elastomer. Furthermore, to minimize variations in quality, the particle size distribution D90 / D10 of the easily breakable layer is preferably 1 to 5. Also, from the viewpoint of ease of breakage, the easily breakable layer is preferably a stretched film. 【0060】 <Olefin resin> Regarding olefin resins, the resins listed under <olefin resins> for the base layer can be used. 【0061】 <Resins incompatible with olefin resins> Resins incompatible with olefin resins are incompatible with the olefin resin in the easily fractured layer, causing layer shearing and making the easily fractured layer more susceptible to cohesive fracture. Examples of incompatible resins include styrene resins, polycarbonate resins, and ester resins. Among these, styrene resins are preferred. 【0062】 <<Styrene resin>> Specific examples of styrene-based resins include polystyrene, acrylonitrile styrene resin (AS resin), and acrylonitrile butadiene styrene resin (ABS resin). From the viewpoint of incompatibility with olefin-based resins and ease of availability, polystyrene is preferred. 【0063】 <particle> The particles in the easily breakable layer are larger in diameter compared to the fillers mixed into the substrate, and are also added in small quantities. From the viewpoint of providing release properties and preventing blistering (air release during molding), it is preferable that the particles have a predetermined average particle size, and from the viewpoint of providing stable release properties, they are added in a predetermined amount. The particles in the easily fractured layer can be the same as those used as fillers in the base layer. Among these, zeolite is preferred due to its low cost, ease of availability, and ease of controlling particle size and particle size distribution. 【0064】 The average particle diameter (D50) is preferably 3 μm or more at the lower limit, more preferably 5 μm or more, and particularly preferably 7 μm or more. Furthermore, the upper limit is preferably 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. If the average particle diameter falls below the lower limit or exceeds the upper limit, it becomes difficult to impart sufficient peelability and blistering properties. The particle size distribution is represented by D90 / D10. A D90 / D10 value closer to 1 indicates a sharper particle size distribution. Note that 1 is a theoretical value and cannot be less than 1. In the formula, D90 represents the particle size at which the cumulative value in volume frequency particle size distribution measurement reaches 90%. D50 represents the particle size at which the cumulative value in volume frequency particle size distribution measurement reaches 50%, and D50 also represents the average particle size. D10 represents the particle size at which the cumulative value in volume frequency particle size distribution measurement reaches 10%. The particles according to the present invention preferably have a D90 / D10 value of 5 or less as an upper limit, more preferably 3 or less, and even more preferably 2.5 or less. The lower limit is 1 or more as a theoretical value. 【0065】 The amount of particles is preferably 15 parts by mass or less, more preferably 13 parts by mass or less, and particularly preferably 11 parts by mass or less, relative to the total resin components of the easily breakable layer. If the amount exceeds the upper limit, it becomes difficult to achieve stable peeling performance, and variations will occur from product to product. Furthermore, the lower limit of the amount of particles is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and particularly preferably 3 parts by mass or more. If the amount falls below the lower limit, the function of imparting roughness as (large diameter) particles will not be exhibited. 【0066】 <Styrene-based elastomer> By incorporating a styrene-based elastomer into the easily fractured layer, the adhesion within the easily fractured layer is increased, improving moldability. Examples of styrene-based elastomers include ABA-type block polymers such as styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butylene copolymer-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), and styrene-butadiene-butylene-styrene (SBBS); AB-type block polymers such as styrene-butadiene (SB), styrene-isoprene (SI), styrene-ethylene-butylene copolymer (SEB), and styrene-ethylene-propylene copolymer (SEP); styrene-based random copolymers such as styrene-butadiene rubber (SBR); and ABC-type styrene-olefin crystalline block polymers such as styrene-ethylene-butylene copolymer-olefin crystals (SEBC). Among these, styrene-butadiene-styrene (SBS) is preferred from the viewpoint of operability. 【0067】 The modulus of elasticity of the styrene-based elastomer is preferably 100 MPa or less, more preferably 50 MPa or less, and even more preferably 20 MPa or less. If the modulus of elasticity is below the above upper limit, sufficient interlayer adhesion with the heat seal layer is easily obtained. The lower limit of the modulus of elasticity is not particularly limited, but is usually 0.1 MPa or more, and is preferably 0.5 MPa or more from the viewpoint of suppressing excessive tackiness. 【0068】 The above modulus of elasticity is measured as follows. A styrene-based elastomer is formed into a 500 μm thick sheet using a hydraulic press, and this is cut into 30 mm x 15 mm sections to prepare test specimens. Dynamic viscoelasticity measurements of these test specimens are performed using a solid viscoelasticity analyzer (RSA-III, manufactured by T.A. Instruments Japan). The measurement conditions are: chuck distance 20 mm, measurement frequency 10 Hz, strain 0.1%, heating rate 10 °C / min, tensile mode, and the storage modulus in the TD direction (vertical direction) at 23 °C is determined as the modulus. 【0069】 From the viewpoint of suppressing unnecessary peeling under normal use conditions, the content of styrene-based elastomer in the easily breakable layer is 15 parts by mass or more, preferably 25 parts by mass or more, and more preferably 40% by mass or more, based on 100 parts by mass of the total resin components in the easily breakable layer. From the viewpoint of easily peeling the easily breakable layer from the heat seal layer when force is applied by hand, the content of styrene-based elastomer in the easily breakable layer is 65 parts by mass or less, preferably 55 parts by mass or less, per 100 parts by mass of the total resin components in the easily breakable layer. 【0070】 The easily fractured layer may contain the additives listed in the <other components> of the base layer, to the extent that they do not impair the effects of the present invention. 【0071】 (Coated layer) When printing on a label, it is preferable to provide a printing coating layer on the surface of the base layer opposite the heat-seal layer, from the viewpoint of adhesion with the ink. Alternatively, a printing layer may be laminated on this coating layer, or the coating layer itself may be the printing layer. In the latter case, the coating layer is formed by directly printing on the surface of the base layer opposite the heat-seal layer. In the former case, the coating layer can be formed, for example, by applying a coating agent to the surface of the base layer. 【0072】 [Characteristics of laminated films] (Thickness) The thickness of the base layer is preferably 10 μm or more, and more preferably 30 μm or more. If the thickness of the base layer is above the lower limit, it tends to be easier to obtain a laminated film with the desired stiffness and rigidity. On the other hand, the thickness of the base layer is preferably 300 μm or less, and more preferably 150 μm or less. If the thickness of the base layer is below the upper limit, the flexibility of the laminated film tends to increase, and it is easier to conform to the shape of the container. 【0073】 The thickness of the heat seal layer is preferably 1 μm or more. If the thickness of the heat seal layer is above the lower limit, sufficient adhesive strength to the container is more easily obtained. On the other hand, the thickness of the heat seal layer is preferably 50 μm or less. If the thickness of the heat seal layer is below the upper limit, stickiness is reduced and the laminated film becomes easier to cut, which tends to improve the processability of the laminated film. 【0074】 From the viewpoint of reducing peeling under normal use, the thickness of the easily breakable layer is preferably 0.1 μm or more, and more preferably 0.5 μm or more. From the viewpoint of facilitating peeling by hand, the thickness of the easily breakable layer is preferably 10 μm or less, and more preferably 5 μm or less. 【0075】 (Smoothness) The smoothness of the heat-seal layer side surface of the laminated film is preferably 1000s or less, more preferably 350s or less, even more preferably 300s or less, and particularly preferably 250s or less. If the smoothness is below the above upper limit, the surface irregularities on the heat-seal layer side increase, making it easier to form air channels between the heat-seal layer and the container. This allows for the formation of air channels that can sufficiently release air that enters during application to the outside, thereby reducing the occurrence of blisters. The lower limit of the above smoothness is usually 10s or more, preferably 100 seconds or more, more preferably 120 seconds or more, and even more preferably 160 seconds or more. 【0076】 The above smoothness is the Wang-Ran type smoothness measured according to JIS-P8119:1998. The above-mentioned smoothness can be adjusted to the above range by incorporating particles into the easily fractured layer. 【0077】 (Peel Strength) From the viewpoint of reducing peeling under normal use conditions, the peel strength between the substrate layer and the heat seal layer of the laminated film is preferably 450 gf / 15 mm or less, more preferably 400 gf / 15 mm or less, and even more preferably 300 gf / 15 mm or less. From the viewpoint of easy peeling by hand after use, the above peel strength is preferably 25 gf / 15 mm or more, more preferably 50 gf / 15 mm or more, and even more preferably 100 gf / 15 mm or more. 【0078】 The above peel strength is measured as the peel force obtained by a T-type tensile test at a draw speed of 300 mm / min under test conditions of 20-23°C and 50-60%RH, in accordance with JIS K6854-2:1999. 【0079】 [Method for manufacturing laminated film] The method for manufacturing the laminated film of the present invention is not particularly limited. For example, the laminated film of the present invention can be manufactured by forming each layer of film and then laminating them together. 【0080】 (Film formation) As for the method of forming each layer of film, for example, casting, calendering, rolling, or inflation molding can be used, in which molten resin is extruded into a sheet shape using single-layer or multi-layer T-dies, I-dies, etc., connected to a screw-type extruder. Alternatively, a film may be formed by casting or calendering a mixture of resin and an organic solvent or oil, and then removing the solvent or oil. 【0081】 Methods for laminating films include co-extrusion, extrusion lamination, and coating, and these can be combined. In co-extrusion, the resin compositions of each layer, which have been melt-kneaded in separate extruders, are laminated and extruded in a feed block or multi-manifold, performing film formation and lamination in parallel. In extrusion lamination, another film is formed and laminated by melt-extruding a resin composition onto a pre-formed film. In coating, another film is formed and laminated by coating a resin solution, emulsion, or dispersion onto a film and drying it. The heat-seal layer can be provided not only by co-extrusion and lamination but also by coating or application. 【0082】 (Stretching) Each layer may be stretched individually before lamination, or they may be stretched together after lamination. Furthermore, the unstretched and stretched layers may be stretched again after lamination. 【0083】 Applicable stretching methods include, for example, longitudinal stretching using the difference in peripheral speed of a group of rolls, transverse stretching using a tenter oven, sequential biaxial stretching combining these methods, rolling, simultaneous biaxial stretching using a combination of a tenter oven and a pantograph, and simultaneous biaxial stretching using a combination of a tenter oven and a linear motor. In addition, simultaneous biaxial stretching (inflation molding), in which molten resin is extruded into a tube shape using a circular die connected to a screw-type extruder and then air is blown into it, can also be used. 【0084】 When stretching is performed, the stretching temperature is preferably in a range above the glass transition temperature of the thermoplastic resin used in the film if the thermoplastic resin is an amorphous resin. If the thermoplastic resin is a crystalline resin, the stretching temperature is preferably in a range above the glass transition temperature of the amorphous portion of the thermoplastic resin and below the melting point of the crystalline portion of the thermoplastic resin, specifically a temperature 2 to 60°C lower than the melting point of the thermoplastic resin. 【0085】 The stretching speed is not particularly limited, but from the viewpoint of stable stretch molding, it is preferable to be in the range of 20 to 350 m / min. Furthermore, the stretching ratio can be appropriately determined considering the characteristics of the thermoplastic resin used. For example, when stretching a resin film containing a propylene homopolymer or copolymer thereof in one direction, the stretching ratio is usually 1.2 times or more, preferably 2 times or more, while it is usually 12 times or less, preferably 10 times or less. When biaxially stretched, the stretching ratio is an area stretching ratio, which is usually 1.5 times or more, preferably 10 times or more, while it is usually 60 times or less, preferably 50 times or less. 【0086】 (Formation of the coated layer) A coating layer for printing can be formed on the surface of the substrate layer opposite to the heat-sealed layer. After forming the coating layer, various known printing methods can be used, including offset printing, gravure printing, flexographic printing, letterpress printing, screen printing, inkjet recording, thermal recording, thermal transfer recording, and electrophotographic recording. Among these, offset printing, gravure printing, or flexographic printing are preferred as they easily produce printed materials with excellent weather resistance and water resistance, and gravure printing is preferred for packaging applications. Furthermore, oil-based inks, water-based inks, or UV-curable inks can be used as printing inks. 【0087】 (Processing of laminated films) The laminated film of the present invention may be processed into a shape or size necessary for attachment to a container by cutting or punching. 【0088】 [container] The container of the present invention preferably contains the same type of resin as the resin contained in at least a portion of the heat-seal layer of the laminated film. For example, if the heat-seal layer contains low-density polyethylene, the container body may contain an ethylene-based resin. In this case, the laminated film described above is attached to the container body, and such a labeled container can be manufactured by heat-sealing the heat-seal layer side of the laminated film to the container body. Specifically, as described above, the laminated film can be used as an in-mold label, and the laminated film can be attached by heat during in-mold molding of the container. 【0089】 For example, ethylene-based resins that can be used for the container body have a density of 0.940 to 0.965 g / cm³. 3 High-density polyethylene, with a density of 0.925-0.935 g / cm³ 3 Examples include medium-density polyethylene. [Examples] 【0090】 The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts," "%," etc., in the examples refer to mass-based measurements. 【0091】 [Raw materials] Table 1 shows a list of the raw materials used in the examples and comparative examples. [Table 1] 【0092】 [Manufacturing of laminated films] (Example 1) A resin composition (a) consisting of 84 parts by mass of thermoplastic resin (propylene homopolymer, trade name: Novatec PP FY-4, manufactured by Nippon Polypropylene Co., Ltd., MFR (230℃, 2.16 kg load): 5.0 g / 10 min, melting point: 165℃) and 16 parts by mass of filler (heavy calcium carbonate fine powder, trade name: Softon #1800, manufactured by Bihoku Powdering Industry Co., Ltd., volume average particle size: 1.8 μm) was melt-kneaded in an extruder set to 230℃. Then, it was supplied to an extrusion die set to 250℃ and extruded into a sheet, which was cooled to 60℃ using a cooling device to obtain an unstretched sheet. This unstretched sheet was heated to 135℃ and stretched five times in the longitudinal direction using the difference in peripheral speed of the roll group to form a base layer. 【0093】 Next, 70 parts by mass of low-density polyethylene (high-pressure low-density polyethylene, product name: Novatec LD LC522, manufactured by Nippon Polyethylene Co., Ltd., MFR (190℃, 2.16kg load): 4g / 10min, density: 0.923g / cm³) 3 A resin composition (b) for forming a heat seal layer was prepared by melt-kneading 30 parts by mass of a polyolefin-based elastomer (α-olefin copolymer, trade name: Toughmer PN3560, manufactured by Mitsui Chemicals, MFR (230℃, 2.16 kg load): 6.0 g / 10 min, melting point: 160℃), and 0.5 parts by mass of a lubricant (ethylene bisoleamide, trade name: Slipax O, manufactured by Nippon Chemical Corporation, melting point: 119℃) in an extruder set to 250℃. 【0094】 To another extruder, 45 parts by mass of thermoplastic resin (propylene homopolymer, trade name: Novatec PP FY-4, manufactured by Nippon Polypropylene Co., Ltd., MFR (230℃, 2.16 kg load): 5.0 g / 10 min, melting point: 165℃), 45 parts by mass of polystyrene resin (polystyrene resin, trade name: HIPS 475D, manufactured by PS Japan Co., Ltd., MFR (200℃, 2.16 kg load): 2 g / 10 min)), 1 part by mass of compatibilizer (styrene-butadiene copolymer, trade name: P2000, manufactured by Asahi Kasei Corporation, MFR (230℃, 2.16 kg load): @@ g / 10 min, melting point: 160℃), and 8 parts by mass of large-diameter particles (zeolite, trade name: Silton AMT100, manufactured by Mizusawa Chemical Industries Co., Ltd., average particle size 8 μm) were supplied. This was melt-kneaded in an extruder set to 250°C to prepare a resin composition (c) for forming an easily fractured layer. 【0095】 Next, resin compositions (b) and (c) were co-extruded onto the base layer from each extruder in sheet form to obtain a three-layer sheet laminated in the order of base layer / easily broken layer / heat-seal layer. After cooling this three-layer sheet to 60°C using a cooling device, it was heated to approximately 150°C using a tenter oven and stretched 8.5 times in the transverse direction. Then, it was heat-treated by heating to 160°C, cooled to 60°C, and the edges were slit. 【0096】 This resulted in a laminated film (total layer thickness: 100 μm, individual layer thicknesses: 70 μm / 20 μm / 10 μm, number of stretch axes in each layer: 2 axes / 1 axis / 1 axis) with the layers stacked in the order of base layer / easily broken layer / heat seal layer. This laminated film was punched out to a size of 63 mm × 125 mm to obtain the laminated film of Example 1. 【0097】 (Examples 2 and 3, Comparative Example 3) Subsequently, laminated films for Examples 2, 3, and Comparative Example 3 were obtained in the same manner as in Example 1, except that the proportions of thermoplastic resin and polystyrene resin in the easily fractured layer were changed as shown in Table 2 below. 【0098】 (Example 4) The laminated film of Example 4 was obtained in the same manner as in Example 1, except that the amount of compatibilizer in the easily fractured layer was changed as shown in Table 2 below. 【0099】 (Comparative Examples 1 and 2) Laminated films of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the amount of large-diameter particles in the easily fractured layer was changed as shown in Table 2 below. In the case of Comparative Example 2, the surface of the heat-sealed layer side of the obtained laminated film was embossed. 【0100】 [Measurement of physical properties] For each example and comparative example of laminated film, the surface smoothness on the heat-seal layer side and the peel strength between the heat-seal layer and the easily fractured layer were measured. 【0101】 (Smoothness) The surface smoothness (s) of the heat-sealed layer side of the laminated film was measured according to JIS-P8119:1998. 【0102】 (Peel strength) Each laminated film was used as an in-mold label to manufacture labeled containers. Each laminated film was fixed to one side of a blow molding die using vacuum. The laminated films were fixed so that the base layer side was in contact with the die. Meanwhile, high-density polyethylene (HDPE) (product name: Novatec HD HB330, manufactured by Nippon Polychem Co., Ltd., melting point 134°C) was melt-extruded at 200°C to form a parison. This parison was used to clamp the die, and a pressure of 4.2 kg / cm² was applied. 2 Compressed air was supplied into the parison. This caused the parison to inflate and form a container shape, and it was heat-fused to the laminated film. After molding, the mold was cooled and opened to obtain a hollow, labeled resin container with a capacity of 1000 ml. 【0103】 The label portion of the above-mentioned labeled resin container was cut off with a cutter, and a measurement sample measuring 12 cm in length and 15 mm in width was taken. Next, the label was carefully peeled off from the edge of the measurement sample by about 1 cm to form a gripping area. Based on JIS K6854-2:1999, the measurement sample was set in a tensile testing machine (Shimadzu Autograph AGS-5kNJ) and a 180-degree peel test was performed under the condition of a peeling speed of 300 mm / min. The average value of the peel strength (gf / 15 mm) between peel lengths of 25 mm and 75 mm was calculated. 【0104】 During the measurement of delamination strength, delamination between easily fractured layers was confirmed as follows: (1) Perform FTIR measurement on the label peeled off the resin container and confirm that there are no peaks caused by components used in the heat seal layer, such as polyethylene components. (2) No white, opaque fragments can be visually confirmed on the resin container side. The fragments to be examined in (2) above are fragments of the base material that remain on the resin container side due to the material failure of the base material layer. If the label peels off due to the material failure of the base material layer, a white opaque base material layer with voids formed by the filler remains on the surface of the resin container. Therefore, if the white opaque cross section cannot be visually confirmed, it is presumed that the label was peeled off without the base material layer failing. If the base material layer, which has voids and the lowest mechanical strength, has not failed, then material failure at the easily breakable layer is unlikely. Furthermore, since both the base material layer and the easily breakable layer are made of polypropylene and are more firmly adhered than the easily breakable layer and the heat seal layer, it is thought that the peeling occurred between the easily breakable layer and the heat seal layer. 【0105】 [evaluation] The blister suppression and ease of peeling of the laminated films of each example and comparative example were evaluated as follows. 【0106】 (Manufacturing of labeled containers) Each laminated film was used as an in-mold label to manufacture labeled containers. The labeled containers were manufactured in the same manner as when the interlayer strength was measured. 【0107】 (Blister suppression) The label portion of the above-mentioned labeled resin container was visually inspected for any lifting or blistering caused by the peeling of the label, and the blister suppression was evaluated according to the following criteria. A (Good): No blistering occurred at all. B (Acceptable): Three or fewer small blisters with a diameter of 0.5 mm or less are generated. E (Not acceptable): Blisters larger than 0.5 mm in diameter occur, or four or more of the above-mentioned small blisters occur. 【0108】 (Peel stability (ease of fracture)) From the labeled containers described above, the edges of the label were peeled off with a fingernail. Then, the peeled portion was grasped by hand and the label was peeled off from a position at a 180° angle to the surface of the container body. The way the label peeled off was observed, and the manual peeling stability was evaluated according to the following criteria. A (Good): The label could be completely removed from the container, and no fragments or other material from the label remained on the container. B (Acceptable): The label was completely removed from the container, but some fragments of the label remained on the container. E (Unacceptable): The label could not be completely removed from the container, and fragments of the label remained on the container. 【0109】 (Printability) The laminated films of the examples and comparative examples were cut to A5 size and then conditioned for one day at a temperature of 23°C and a relative humidity of 50%RH. After that, solid printing was performed on the coated layer of printing paper with an ink amount of 2.0 g / m2. UV flexographic ink (product name: Flexo 500, manufactured by T&K TOKA Corporation) was used for printing. Next, UV irradiation was performed using a UV irradiator to achieve an irradiation intensity of 100 mJ / cm2, and samples for ink adhesion evaluation were obtained. The samples were visually observed, and the printing performance was evaluated based on the uniformity of the print according to the following criteria. A: No variation in ink density is observed (Pass) B: Slight variation in ink density is observed (Pass) E: Ink density variations are visible (unacceptable) 【0110】 (Prevention of printing defects after storage) The laminated films of the examples and comparative examples were cut to A5 size and then conditioned for one day at a temperature of 23°C and a relative humidity of 50%RH. After that, 100 sheets were stacked and placed in a press, and pressed at a pressure of 5MPa for 5 minutes. After pressing, the 50th laminated film from the top was removed, and printing and measurements were performed in the same manner as for the printability described above to confirm the ability to prevent printing defects after storage (whether the lubricant would transfer due to pressure from stacking during storage, thus reducing printability). 【0111】 Table 2 shows the evaluation results. [Table 2] 【0112】 The peel strength of Examples 1-4 was 100 (gf / 15mm) or higher in all cases, confirming sufficient adhesion to prevent the labels from peeling off during use of the containers. On the other hand, the interlayer strength of Examples 1-4 was 300 (gf / 15mm) or lower in all cases, indicating good peelability, meaning that the labels could be easily removed by hand. 【0113】 Comparing Example 1 with Comparative Example 1, blistering was observed in Comparative Example 4, where large-diameter particles were not incorporated into the easily fractured layer. Comparing Example 1 with Comparative Example 2, in Comparative Example 2, embossing was applied instead of incorporating large-diameter particles into the easily fractured layer, resulting in a regular uneven surface, excessive transfer of the lubricant in the heat seal layer, and transfer failure. Comparing Example 1 with Comparative Example 3, in Comparative Example 3, where an incompatible resin such as styrene-based resin was not incorporated into the easily fractured layer, no easy fracture occurred and it could not be peeled off by hand. 【0114】 This application claims priority based on Japanese Patent Application No. 2022-186457, filed on November 22, 2022, and incorporates all the contents of said Japanese Patent Application. [Explanation of Symbols] 【0115】 10. Laminated film 1...Base material layer 2. Heat seal layer 3. Easily Destructible Layer 4. Coating layer

Claims

[Claim 1] A laminated film having a base layer and an easily breakable layer in this order, The aforementioned substrate layer contains an olefin resin, The easily fractured layer contains the olefin resin, a resin incompatible with the olefin resin, and particles, wherein the particles have an average particle diameter of 3 to 20 μm, and the amount of particles is 15 parts by mass or less relative to the total resin components in the easily fractured layer, and the void ratio of the easily fractured layer is 10% or less. Laminated film. [Claim 2] A laminated film having a heat-seal layer on the side opposite to the substrate layer of the easily fractured layer, The heat seal layer contains a resin with a lower melting point than the olefin resin. The laminated film according to claim 1. [Claim 3] The particle size distribution D90 / D10 of the easily fractured layer is 1 to 5. The laminated film according to claim 1. [Claim 4] The easily breakable layer is a stretched film. The laminated film according to claim 1. [Claim 5] The heat seal layer further contains a lubricant. The laminated film according to claim 1. [Claim 6] The substrate layer further comprises a printing coating layer on the surface opposite to the heat seal layer. The laminated film according to claim 1. [Claim 7] The peel strength of the easily fractured layer is 100 to 300 gf / 15 mm. The laminated film according to claim 1. [Claim 8] A container having a laminated film according to any one of claims 1 to 7 attached to a resin container body.

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