Laminate

Abstract

Provided is a laminate which has enhanced adhesiveness between the laminate and a container even when silicone is transferred from a protective layer side to a heat seal layer side and which has transparency. This laminate is an in-mold label including a substrate layer, a heat seal layer, and a coat layer, wherein the coat layer contains thermoplastic resin particles and a (meth)acrylic acid-based copolymer, the thermoplastic resin particles have an average particle diameter of 0.01-0.80 μm, and the (meth)acrylic acid-based copolymer has a polar group.

Description

Technical Field

[0001] The present invention relates to a laminate.

Background Art

[0002] As methods of in-mold molding, there are a blow molding method and an injection molding method. Blow molding is a method of forming a resin container by placing a lump of molten cylindrical raw material resin between split molds and applying air pressure from the inside to expand the lump of raw material resin. Further, the injection molding method is a method of forming a resin container by injecting raw material resin between a concave mold and a convex mold. The blow molding method further includes a direct blow method and a stretch blow method. The direct blow method is a method of forming a resin container by heating raw material resin above its melting point to melt it to form a parison and applying air pressure to the parison in a mold to expand it. The stretch blow method is a method of forming a resin container by placing a preform previously formed from raw material resin in a mold, stretching the preform with a rod near the softening point of the raw material resin, and applying air pressure to expand it.

[0003] As a label for a resin container blow-molded as described above, an in-mold label that is heat-sealed to the surface of the resin container by heat during molding is used. For example, an in-mold label in which a heat-sensitive adhesive layer containing an ethylene-vinyl acetate copolymer is laminated on a polypropylene film is used for a polyethylene container (see, for example, Patent Document 1).

[0004] In addition, an in-mold label has been proposed that includes a heat-sealable resin layer containing a polyethylene-based resin on a base material layer and enhances the adhesiveness to polyethylene terephthalate by subjecting the heat-sealable resin layer to a surface oxidation treatment (see, for example, Patent Document 2).

[0005] On the other hand, in some cases, after forming a printed layer on an in-mold label by printing product information, a protective layer is applied on top of the printed layer to prevent scratches, stains, etc. The protective layer is formed by applying a coating liquid called overprint varnish. The coating liquid includes, for example, curable resins such as acrylic resin, urethane resin, and epoxy resin.

[0006] Some coating solutions contain silicone to improve the surface slipperiness of in-mold labels. In-mold label sheets are stored either cut and stacked or wound into rolls. When silicone is added, it can migrate from the protective layer of an in-mold label to the in-mold label stacked on top of it. The surface of the in-mold label that is in contact with the protective layer is the adhesive surface to the container, and a decrease in adhesion due to this silicone migration has been observed.

[0007] Furthermore, in order to suppress the decrease in adhesion of the in-mold label even when silicone migrates from the protective layer to the heat-sealable resin layer, a technique has been proposed to provide an adhesion strength reduction suppression layer containing a (meth)acrylic acid copolymer having polar groups on the outermost surface of the heat-sealable resin layer side of the in-mold label (see, for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2004-136486 [Patent Document 2] Japanese Patent Publication No. 2018-060185 [Patent Document 3] International Publication No. WO2020 / 067327 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, while Patent Document 3 can suppress the reduction in adhesive strength, there was still room for further improvement regarding the inherent adhesive strength. In addition, in-mold labels require transparency from the perspective of aesthetics when combined with the container, so there was still room for further research and development.

[0010] The present invention aims to provide a laminate that maintains adhesion to a resin container and is transparent, even when silicone migrates from the protective layer to the heat-seal layer.

[0011] As a result of diligent research conducted by the present inventors to solve the above problems, they discovered that by providing a laminate comprising a base layer, a heat seal layer, and a coating layer, and by providing the coating layer with a (meth)acrylic acid copolymer and thermoplastic resin particles having a predetermined average particle size, the adhesion between the laminate and the resin container is enhanced and transparency is achieved, thus completing the present invention. In other words, the present invention is as follows:

[0012] [1] A laminate comprising a base layer, a heat seal layer, and a coating layer, The coating layer comprises thermoplastic resin particles and (meth)acrylic acid-based copolymer. The thermoplastic resin particles have an average particle size of 0.01 to 0.80 μm. The (meth)acrylic acid copolymer has polar groups. Laminated structure.

[0013] [2] The laminate according to [1] above, wherein the average particle size of the thermoplastic resin particles is 0.01 to 0.45 μm.

[0014] [3] The laminate described in [1] or [2] above, wherein the haze value is 60% or less.

[0015] [4] The laminate according to [1] or [2] above, wherein the (meth)acrylic acid copolymer has primary to tertiary amino groups.

[0016] [5] The laminate according to [1] or [2] above, wherein the (meth)acrylic acid copolymer has a melting point of less than 60°C or does not have a melting point.

[0017] [6] A label used by adhering it to a resin container which is a stretch blow molded body, The absolute value of the area-dimensional change rate at 80°C is 1% or less. The tack force at 80°C is 0.8 N / cm. 2 The following is The laminate described in [1] above.

[0018] [7] The tack force at 90°C is 1.2 N / cm 2 The laminate described in [6] above, which is less than [6].

[0019] [8 The laminate according to [6] or [7] above, wherein the heat of fusion rate of the heat seal resin of the heat seal layer at 80°C is 80% or less.

[0020] [9] The heat seal layer comprises a first heat seal resin and a second heat seal resin, The melting point of the first heat seal resin is 75 to 85°C. The melting point of the second heat-seal resin is 95 to 105°C. The laminate described in [6] or [7] above. [Effects of the Invention]

[0021] According to the present invention, even when silicone migrates from the protective layer to the heat-seal layer, a laminate can be provided that maintains adhesion to the resin container and is also transparent. [Brief explanation of the drawing]

[0022] [Figure 1] This is a cross-sectional view showing the structure of the laminate 1. [Figure 2] As an example of use, this is a cross-sectional view of an in-mold label 10 when a protective layer 5 and a printed layer 3 are placed on a laminate 1. [Figure 3]This is a flowchart illustrating part of the recycling process. [Figure 4] This figure shows an example of a resin container with an in-mold label attached. [Modes for carrying out the invention]

[0023] The laminate of the present invention will be described in detail below. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto. In the following explanation, the term "(meth)acrylic" refers to both acrylic and methacrylic.

[0024] (Laminated structure) The laminate of the present invention comprises, for example, a base layer, a heat-seal layer, and a coating layer. The laminate of the present invention is used to adhere to a resin container by in-mold molding (i.e., it is a laminate for in-mold molding). In the laminate of the present invention, the coating layer contains thermoplastic resin particles and a (meth)acrylic acid copolymer. The thermoplastic resin particles have an average particle size of 0.01 to 0.80 μm. The (meth)acrylic acid copolymer has polar groups.

[0025] The laminate includes a heat-seal layer and a coating layer, and the coating layer contains thermoplastic resin particles and a (meth)acrylic acid copolymer, thereby enhancing adhesion to the resin container. When thermoplastic resin particles are used, transparency may be impaired due to diffuse reflection of light. However, in the laminate according to this embodiment, since the thermoplastic resin particles have a relatively small average particle size of 0.80 μm or less, transparency can be obtained while maintaining adhesion.

[0026] The average particle size of the thermoplastic resin particles is preferably 0.01 to 0.45 μm, as this provides even better transparency.

[0027] The haze value of the laminate is preferably 60% or less, as this allows for the aesthetic appeal inherent in transparency.

[0028] The (meth)acrylic acid copolymer preferably has primary to tertiary amino groups, as this further improves its adhesive properties. Furthermore, the (meth)acrylic acid copolymer preferably has a melting point of less than 60°C or no melting point, in order to distinguish it from heat-seal resins.

[0029] Furthermore, the laminate is particularly preferable when used by bonding it to a resin container that is a stretch blow molded body, as it provides a label peeling effect during the recycling process. From the viewpoint of achieving the above-mentioned label peeling effect, the laminate preferably has an absolute value of 1% or less in area dimensional change rate at 80°C, and a tack force of 0.8 N / cm at 80°C. 2 The following is preferable:

[0030] The above area-dimensional change rate is calculated as the percentage change (%) of the product of the dimensions in the TD (Transverse Direction) and MD (Machine Direction) directions of the laminate when the temperature changes from 0°C to 80°C. A detailed measurement method will be described later.

[0031] Generally, in-mold labels (and in-mold molding laminates) are placed in molds used for in-mold molding of resin containers, and melt due to the heat generated during molding, adhering to the surface of the resin container. As a result, the in-mold label adheres to the resin container over its entire surface, making mechanical removal difficult. Therefore, in order to remove the laminate from the resin container, a high-temperature immersion treatment is sometimes used during the recycling process, in which the labeled container is immersed in high-temperature water or an alkaline aqueous solution. The treatment temperature in this case is usually 80-90°C.

[0032] The laminate of the present invention has a tack force of 0.8 N / cm at 80°C. 2Because the rate of change in area and dimensions at 80-90°C is low, the laminate becomes more easily detached from the resin container during high-temperature immersion treatment. Furthermore, the absolute value of the area and dimension change rate of the laminate of the present invention at 80°C is 1% or less, meaning it hardly shrinks at all. Therefore, for resin containers that shrink by more than 1% in absolute value of the area and dimension change rate at 80°C, stress is generated between the label and the container due to the difference in shrinkage, and this stress makes the label more easily detached. In this way, the laminate of the present invention, designed to improve peelability during high-temperature immersion treatment, can improve the recyclability of resin containers.

[0033] In injection molding and direct blow molding, molten resin is molded, so stretch stress is less likely to be applied. On the other hand, in stretch blow molding, a semi-molten preform is expanded by strong blow pressure, so stretch stress is applied.

[0034] Therefore, when a stretch-blown molded article is subsequently heated again to near the temperature at which it was molded, stress is generated, and it tends to contract in the opposite direction to the direction of expansion. Furthermore, when using an ester-based resin, particularly polyethylene terephthalate (PET), as the raw material resin and molding by the stretch-blow method, the temperature of the preform and the stretch-blow molding can be, for example, 70 to 150°C, 80 to 120°C, or 90 to 115°C. Therefore, resin containers molded by the stretch-blow method are particularly prone to shrinkage during high-temperature immersion treatment, and especially ester-based resin containers are prone to shrinkage during high-temperature immersion treatment heated to 80 to 90°C, which tends to widen the difference in area dimensional change rate with the laminate of the present invention. Therefore, the laminate and in-mold label of the present invention are prone to peeling from resin containers molded by the stretch-blow method, and even more prone to peeling from ester-based resin containers. For this reason, the laminate and in-mold label of the present invention can preferably be used as labels for stretch-blown molded articles, or as labels for ester-based resin molded articles that are stretch-blown molded articles.

[0035] From the viewpoint of making it easier to peel off the laminate and in-mold label during recycling, the tack force of the laminate of the present invention at a temperature of 90°C is 1.2 N / cm 2 Preferably less than 1 N / cm 2 The following is more preferable: The tack force is, for example, 0.6 N / cm. 2 That's all.

[0036] From the viewpoint of further separation effect during high-temperature immersion treatment, it is preferable that the heat of fusion rate of the heat-seal resin at 80°C be 80% or less.

[0037] Furthermore, from the viewpoint of facilitating adjustment of tack force, the heat-seal layer of the laminate may contain a first heat-seal resin and a second heat-seal resin. Preferably, the melting point of the first heat-seal resin is 75 to 85°C, and the melting point of the second heat-seal resin is 95 to 105°C.

[0038] (Example of laminate and in-mold label configuration) Figure 1 shows an example of the structure of the laminate of the present invention. Figure 1 is a cross-sectional view of the laminate 1. The laminate 1 is a laminated film having a coating layer 6, a heat seal layer 4, and a base layer 2 in that order. The coating layer 6 contains thermoplastic resin particles and a (meth)acrylic acid copolymer.

[0039] Furthermore, as shown in Figures 2A and 2B, a protective layer 5 may be provided on the substrate layer 2 side of the laminate 1 for ease of transport. A printed layer 3 may also be applied to the substrate layer 2 by printing. A protective layer 5 containing silicone 51 may be applied on top of that. In this way, an in-mold label 10 can be obtained by providing the printed layer 3 and the protective layer 5 on the laminate 1.

[0040] When in-mold labels are stacked on top of each other, the silicone in the protective layer of one in-mold label may migrate to the heat-seal layer of the other in-mold label stacked on top of that protective layer, potentially reducing the adhesion of the heat-seal layer.

[0041] However, in the laminate of the present invention, a coating layer is provided on the outermost surface on the heat-seal layer side. Because the coating layer is interposed between the protective layer and the heat-seal layer, it is possible to prevent the silicone from migrating directly to the heat-seal layer. Although a release sheet can also be provided on the surface of the protective layer to prevent silicone migration, the coating layer can be easily formed by coating or the like, thus enabling low cost and simplification of the manufacturing process.

[0042] Furthermore, if the protective layer is provided on the outermost surface of one side of the substrate layer, other layers may be provided between the substrate layer and the printed layer, and between the printed layer and the protective layer. Examples of other layers include pattern layers such as transfer foil, holograms, and security threads provided for design purposes, anti-counterfeiting purposes, intermediate layers for adjusting thickness and strength, and functional layers such as polarizing films. Similarly, if the coating layer is provided on the outermost surface of the other side of the substrate layer, the above-mentioned other layers may be provided between the substrate layer and the heat-seal layer.

[0043] As an example of use, Figure 2B shows a cross-sectional view of a single in-mold label 10 after it has been separated from the in-mold labels 10 shown in Figure 2A that were stacked on top of each other. As shown in Figure 2B, silicone 51 has migrated from the other in-mold labels 10 that were stacked on the heat seal layer 4, but the coating layer 6 prevents the silicone 51 from adhering to the heat seal layer 4.

[0044] (Recycling of labeled containers)

[0045] The series of recycling processes, including high-temperature immersion treatment, will be briefly explained using the flowchart in Figure 3. When the plastic container recycling process is carried out, the labeled containers first go through processes such as unpacking, sorting by container material, and manual sorting, before moving on to the crushing process S101.

[0046] In the crushing process S101, the labeled containers are sheared and crushed using shearing blades. The crushed fragments of the labeled containers are then flake-washed by stirring while being immersed at high temperature in a stirring vessel (flake washing process S102). The flake-washed fragments of the resin containers then proceed to the neutralization process and then to the specific gravity separation process S103, where they are finally collected as resin fragments after washing and separation are complete.

[0047] Here, the temperature of the high-temperature immersion treatment in the flake washing process S102 in Figure 3 is typically 80-90°C. The laminate 1 of the present invention has a tack force of 0.8 N / cm at 80°C. 2 The following is the lowest. Therefore, it becomes easier for the resin container to peel off during high-temperature immersion treatment at 80-90°C.

[0048] Furthermore, since the laminate 1 of the present invention has an absolute value of 1% or less in area dimensional change rate at 80°C, it hardly shrinks compared to the resin container 20. As a result, stress is generated due to the difference in shrinkage between the laminate 1 and the in-mold label 10 and the resin container 20, making the label more likely to peel off. Thus, since the laminate 1 of the present invention is designed to enhance the separation effect during high-temperature immersion treatment, the recyclability of the resin container 20 can be improved. Also, as described above, resin containers made by stretch blow molding tend to have a wider difference in area dimensional change rate between the laminate and the in-mold label. In particular, when the area dimensional change rate of the resin container is 4% or more, the above separation effect is even higher and preferable.

[0049] The following explains each layer.

[0050] <Base material layer> The base material layer is not particularly limited as long as it can impart strength to the laminate, and for example, it can be a thermoplastic resin film. That is, the base material layer can be composed of a thermoplastic resin or the like. Examples of the thermoplastic resin include polyolefin resins, polyester resins, polyvinyl chloride resins, polyamide resins, polystyrene resins, and polycarbonate resins. It is more preferable that the thermoplastic resin constituting the base material layer contains a polyolefin resin as the main component. The main component refers to a component that occupies 50% by mass or more based on the total of each resin. When the thermoplastic resin constituting the base material layer contains a polyolefin resin as the main component, the base material layer is a polyolefin resin film.

[0051] Examples of the polyolefin resin that can be used for the base material layer include polypropylene resins and polyethylene resins. Among them, from the viewpoints of moldability and mechanical strength, a polypropylene resin is preferable.

[0052] Examples of the polypropylene resin include isotactic homopolypropylene obtained by polymerizing propylene alone, syndiotactic homopolypropylene and other propylene homopolymers, propylene copolymers mainly composed of propylene and copolymerized with α-olefins such as ethylene, 1-butene, 1-hexene, 1-heptene, 1-octene, and 4-methyl-1-pentene. The propylene copolymer may be a binary system or a multi-component system of ternary or higher, and may be a random copolymer or a block copolymer.

[0053] Examples of the polyethylene resin include high-density polyethylene with a density of 0.940 to 0.965 g / cm 3 medium-density polyethylene with a density of 0.920 to 0.935 g / cm 3 low-density polyethylene with a density of 0.900 to 0.920 g / cm 3Examples include linear low-density polyethylene, copolymers mainly composed of ethylene, copolymers obtained by copolymerizing propylene, butene, hexene, heptene, octene, and α-olefins such as 4-methylpentene-1, maleic acid-modified ethylene-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate copolymers, metal salts of ethylene-methacrylic acid copolymers (metals such as zinc, aluminum, lithium, sodium, potassium, etc.), ethylene-cyclic olefin copolymers, and maleic acid-modified polyethylene.

[0054] One of the above polyolefin resins can be used alone, or two or more can be used in combination.

[0055] Examples of polyester resins that can be used in the base layer include polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate. Examples of polyamide resins that can be used in the base layer include nylon-6, nylon-6,6, nylon-6,10, and nylon-6,12.

[0056] The thermoplastic resin used for the base layer preferably has a melting point of 110°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher. This prevents the base layer from melting at the temperature of the high-temperature immersion treatment, making it easier to maintain the rigidity of the base layer during the high-temperature immersion treatment. Furthermore, it makes it easier to set the stretching temperature to 90°C or higher when stretching occurs, thus reducing thermal shrinkage of the base layer at the temperature of the high-temperature immersion treatment. As a result, it becomes easier to adjust the absolute value of the area dimensional change rate of the laminate to 1% or less.

[0057] In this specification, the melting point and glass transition point of the resin are measured by differential scanning calorimetry (DSC).

[0058] (Filler) The base layer may contain fillers in the thermoplastic resin film that constitutes the base layer. Examples of fillers that can be used in the base layer include inorganic fillers and organic fillers.

[0059] The filler contained in the base layer may be one of the above-mentioned inorganic fillers or organic fillers, or a combination of two or more types.

[0060] From the viewpoint of improving the transparency of the base layer, the filler content in the base layer is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. The base layer may not contain any filler. A filler content of 10% by mass or less prevents the formation of pores during stretching, making it easier to achieve overall transparency of the label.

[0061] Depending on the purpose, the substrate layer may contain additives such as sterically hindered antioxidants (phenol-based, phosphorus-based, amine-based, sulfur-based, etc.), light stabilizers (sterically hindered amine-based, benzotriazole-based, benzophenone-based, etc.), dispersants, lubricants, and antistatic agents.

[0062] The amount of additives in the substrate layer can typically be set independently for each type of additive, from 0.001% to 3% by mass, in order to obtain sufficient effects from the additives while suppressing a decrease in printability.

[0063] (porosity) The porosity of the substrate layer is preferably 5% or less, and more preferably 3% or less. A porosity of 5% or less in the substrate layer makes it easier to achieve transparency. However, a low porosity tends to result in lower thermal insulation of the laminate. When thermal insulation is low, the heat that flows during in-mold molding, when in contact with the molten parison or semi-molten preform constituting the resin container, easily escapes to the outside, and this heat does not effectively contribute to the melting of the heat seal layer, thus tending to reduce adhesive strength. However, according to the laminate of this embodiment, sufficient adhesive strength can be obtained even when the porosity is low. Furthermore, the process of recycling and crushing prevents the heat-seal layer from remaining on the resin container, and the label that adheres to the resin container after the crushing process retains its strength. This strength acts as a repulsive force against the stress caused by the difference in shrinkage during high-temperature immersion, making it easier to peel the heat-seal layer from the resin container.

[0064] (thickness) From the viewpoint of suppressing wrinkle formation during printing and facilitating fixation to the desired position when inserted into the mold, the thickness of the base layer is preferably 20 μm or more, and more preferably 40 μm or more. Furthermore, from the viewpoint of suppressing the reduction in strength due to the thinning of the container at the label boundary when the laminate is placed on a container, the thickness of the base layer is preferably 200 μm or less, and more preferably 150 μm or less. Therefore, the thickness of the base layer is preferably 20 to 200 μm, and more preferably 40 to 150 μm.

[0065] The base layer may be a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, each layer can provide various functions such as white opacity, adhesion to the ink used in the printing layer, heat insulation, and easy peelability.

[0066] Suitable transparent substrate layers include polypropylene-based unoriented films (CPP films), polypropylene-based biaxially oriented films (BOPP films), polyethylene terephthalate-based unoriented films (CPET films), and polyethylene terephthalate-based biaxially oriented films (BOPET films), which do not contain fillers.

[0067] The surface of the substrate layer may be activated by an activation treatment to improve adhesion with the printed layer. Examples of activation treatments include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and ozone treatment. Among these, corona discharge treatment or flame treatment is preferred, and corona treatment is more preferred.

[0068] From a similar viewpoint, a printable layer may be provided between the substrate layer and the printing layer. The printable layer preferably contains at least one of a binder and an antistatic agent to improve adhesion with the printing layer. The printable layer may also contain additives such as antiblocking agents, colorants, defoamers, and antifungal agents as needed.

[0069] (Printing layer) The printed layer is formed by printing for the purpose of adding design elements or information such as images, product names, manufacturer names, usage instructions, and barcodes. The printing method is not particularly limited, and known printing methods such as gravure printing, offset printing, flexographic printing, label printing, and screen printing can be used. In addition, depending on the printing method, inks such as oil-based inks, oxidative polymerization-curing inks, ultraviolet-curing inks, water-based inks, and liquid toner inks can be used.

[0070] Furthermore, the printed layer is not limited to printing by the above printing method, but may also include printing by various printers, hot stamping, cold stamping, transfer foil, and conventionally known decorations such as holograms.

[0071] (protective layer) The protective layer is located on the outermost surface of one side of the substrate layer on which the printed layer is applied. By containing silicone, the protective layer can reduce the coefficient of friction of the outermost surface, thereby reducing damage to the printed layer and preventing soiling. Silicone is a silicon compound having polysiloxane bonds.

[0072] From the viewpoint of reducing the coefficient of friction and improving slipperiness, the Si atom content in the protective layer is preferably 1 atm% or more, more preferably 2 atm% or more, and even more preferably 3 atm% or more. From the viewpoint of reducing bleed-out, the Si atom content in the protective layer is preferably 15 atm% or less, more preferably 8 atm% or less, and even more preferably 6 atm% or less. Therefore, the Si atom content in the protective layer is preferably 1 to 15 atm%, more preferably 2 to 8 atm%, and even more preferably 3 to 6 atm%. The above Si atom content can be determined as the Si atom concentration measured by the XPS method.

[0073] From the viewpoint of facilitating molding, the protective layer is preferably formed by applying a silicone-containing coating liquid onto a substrate layer on which a printed layer is provided. As the coating liquid, a coating liquid called overprint (OP) varnish can usually be used. OP varnish is generally a highly transparent coating liquid containing a resin that hardens by visible light, ultraviolet light, and oxidative polymerization. As the coating liquid, commercially available OP varnish that already contains silicone can be used, or a coating liquid prepared by mixing silicone with OP varnish that does not contain silicone can be used.

[0074] The thickness of the protective layer varies depending on the printing method, but is usually 0.5 to 20 μm, preferably 1 to 10 μm, and more preferably 1.5 to 8 μm. Thicker protective layers tend to have higher slipperiness or abrasion resistance, while thinner layers tend to reduce curing defects.

[0075] (Heat seal layer) The heat seal layer is provided to enhance the adhesion between the laminate and the in-mold label and the container. Generally, during in-mold molding of a container, the in-mold label is positioned inside the mold so that the container and the heat seal layer face each other. The heat generated during in-mold molding melts the heat seal layer, causing the in-mold label (or laminate) to heat-fuse to the surface of the resin container. Furthermore, from the viewpoint of strengthening adhesion, it is preferable to provide a coating layer on the outermost surface of the heat seal layer, as shown in Figure 1.

[0076] The heat-seal layer of the laminate of the present invention exhibits particularly high adhesion to containers made of polyethylene terephthalate (PET) resin. Because PET has a low melt viscosity and it is difficult to maintain the parison shape in the molten state, PET resin containers are usually formed by the stretch-blow method, which heats the material to near its softening point rather than its melting point. Therefore, the heat-sealing of the laminate and in-mold label to the PET resin container is also performed at a heating temperature near the softening point of the PET resin, rather than its melting point. For PET resin containers formed in this manner, it is preferable that the heat-seal layer be a film of a thermoplastic resin with a low melting point of 60-130°C, in order to sufficiently melt the heat-seal resin of the laminate and in-mold label and improve adhesion to the container, even under lower molding conditions compared to the direct-blow method which heats the material above its melting point. A lower melting point allows for sufficient adhesion with less heat. Furthermore, a higher melting point makes film molding easier and reduces issues such as sticking to the roll during film manufacturing. The above melting point can be measured using a differential scanning calorimetry (DSC).

[0077] From the viewpoint of easily adjusting the adhesive strength, it is preferable to use a combination of two or more thermoplastic resins with different melting points as the heat seal resin for the heat seal layer.

[0078] Examples of thermoplastic resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid alkyl ester copolymer (alkyl group has 1 to 8 carbon atoms), and metal salts of ethylene-(meth)acrylic acid copolymer (e.g., salts with metals selected from Zn, Al, Li, K, and Na). Furthermore, thermoplastic resins include random copolymers or block copolymers of α-olefins obtained by copolymerizing at least two comonomers selected from α-olefins having 2 to 20 carbon atoms in their molecules.

[0079] Among these, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene copolymers copolymerized using a metallocene catalyst are preferred.

[0080] Furthermore, in this invention, the laminate needs to have a characteristic that allows for easy separation from the resin container during high-temperature immersion treatment for recycling, while maintaining sufficient adhesive strength between the laminate and the resin container during normal use. For this reason, it is preferable to use a combination of heat-seal resins having different melting points, from the viewpoint of easily adjusting the adhesive strength and improving the separation effect during high-temperature immersion treatment. Specifically, a heat-seal resin having a melting point of 75-85°C for the first heat-seal resin and a melting point of 95-105°C for the second heat-seal resin, with a tack force of 0.8 N / cm at 80°C. 2 It is preferable to adjust and use the product as follows. From this viewpoint, the content ratio (mass ratio) of the first heat seal resin and the second heat seal resin in the heat seal layer is preferably 5:95 to 90:10, more preferably 7.5:92.5 to 70:30, and even more preferably 10:90 to 50:50.

[0081] The heat of fusion rate of the heat-seal resin at 80°C is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. A heat of fusion rate of 80% or less makes it easier for the label to peel off the resin container when immersed at high temperatures.

[0082] The heat-seal resin may contain a tackifier. Examples include hydrogenated petroleum resins, aromatic hydrocarbon resins, and aliphatic hydrocarbon resins. Examples of hydrogenated petroleum resins include partially hydrogenated petroleum resins. Examples of aromatic hydrocarbon resins include terpene resins, rosin resins, and styrene resins. In addition, additives commonly used in the polymer field, such as antifogging agents, lubricants, antiblocking agents, antistatic agents, antioxidants, heat stabilizers, light stabilizers, weather stabilizers, and ultraviolet absorbers, may be included as needed. The content of these additives is usually 0.01 to 5% by mass, independently for each type of additive.

[0083] The heat seal layer may be a single-layer structure consisting only of the thermoplastic resin film described above, or it may be a multilayer structure. If the heat seal layer is a multilayer structure, it may consist, for example, a first heat seal layer on the inside (substrate layer side) and a second heat seal layer on the outside (coating layer side). In this case, the components constituting the second heat seal layer are the same as those listed above as components constituting the heat seal layer. On the other hand, in the first heat seal layer, it is preferable that the heat seal resin contains the first heat seal resin having a melting point of 75 to 85°C as described above. It is preferable that the content of the first heat seal resin in the first heat seal layer is 80% by mass or more. Furthermore, it is preferable that the heat of fusion rate of the heat seal resin in the first heat seal layer at 80°C is 80% or less, more preferably 75% or less, and even more preferably 70% or less.

[0084] When the heat seal layer has a single-layer structure, the thickness of the heat seal layer is preferably 0.5 μm or more, more preferably 0.7 μm or more, and even more preferably 1 μm or more, from the viewpoint of improving adhesion. Furthermore, the thickness of the heat seal layer is preferably 10 μm or less, and more preferably 7 μm or less, from the viewpoint of suppressing cohesive failure within the heat seal layer. Therefore, the thickness of the heat seal layer is preferably 0.5 to 10 μm, and more preferably 0.7 to 7 μm.

[0085] (Coat layer) The coating layer is provided on the outermost surface of the other side of the substrate layer on which the heat seal layer is provided. The coating layer contains thermoplastic resin particles from the viewpoint of providing adhesion. Furthermore, the thermoplastic resin particles have a predetermined average particle size from the viewpoint of transparency. From the viewpoint of maintaining the adhesion of the heat seal layer, it is preferable that the coating layer is laminated adjacent to the heat seal layer. This coating layer can enhance adhesion to the resin container.

[0086] Furthermore, the coating layer contains a (meth)acrylic acid copolymer having polar groups. By including the above (meth)acrylic acid copolymer in the coating layer, the decrease in adhesion due to silicone migration can be suppressed. Laminates or in-mold labels are manufactured as long sheets, then cut and stored stacked as sheets, or wound up and stored in rolls. In the case of in-mold labels without a coating layer, the protective layer of one in-mold label and the heat-seal layer of the other in-mold label are adjacent. In this case, depending on the storage conditions, silicone may migrate from the protective layer to the adjacent heat-seal layer, and a phenomenon has been observed in which the adhesion of the heat-seal layer to which the silicone has migrated decreases.

[0087] On the other hand, in the laminate of the present invention, a coating layer is provided on the outermost surface of the other side of the base layer, and the coating layer is interposed between the heat seal layer and the protective layer, thereby preventing silicone from directly adhering to the heat seal layer. This reduces the influence of silicone on the heat seal layer and suppresses a decrease in adhesiveness.

[0088] The average particle size of the thermoplastic resin particles is in the range of 0.01 to 0.80 μm. Because the thermoplastic resin particles have an average particle size of 0.01 to 0.80 μm, transparency can be obtained while maintaining adhesion. From the viewpoint of transparency, an average particle size of 0.55 μm or less is more preferable, and 0.45 μm is preferable. below It is even more preferable that it be 0.2 μm or less, and particularly preferable that it be 0.2 μm or less.

[0089] Thermoplastic resin particles are, for example, olefin copolymer particles, which can be obtained from an olefin copolymer emulsion. An olefin copolymer is a copolymer containing 50% by mass or more of olefin as a polymerization component. Examples of olefin copolymers include ethylene-(meth)acrylic acid copolymer, alkali (earth) metal salt of ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester-maleic anhydride copolymer, (meth)acrylic acid grafted polyethylene, maleic anhydride grafted polyethylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, maleic anhydride grafted (meth)acrylic acid ester-ethylene copolymer, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-propylene-butene copolymer, maleic anhydride grafted ethylene-butene copolymer, and maleic anhydride grafted propylene-butene copolymer.

[0090] Preferably, the olefin copolymer has a melting or softening point of 130°C or lower, and more preferably, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester-maleic anhydride copolymer, maleic anhydride grafted ethylene-vinyl acetate copolymer, maleic anhydride grafted (meth)acrylic acid ester-ethylene copolymer, maleic anhydride grafted ethylene-propylene-butene copolymer, maleic anhydride grafted ethylene-butene copolymer, or maleic anhydride grafted propylene-butene copolymer. By using these olefin copolymers, the ink receptivity can be improved.

[0091] The melting point of the thermoplastic resin particles is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. In particular, when the thickness of the coating layer is 3 μm or less, and even 1 μm or less, the melting point of the thermoplastic resin particles is 60°C or higher, which suppresses the decrease in transparency caused by the fusion of thermoplastic resin particles when the coating liquid is dried to obtain a coating film.

[0092] As a dispersant for dispersing olefin copolymers in water to form an emulsion, at least one selected from the group consisting of nonionic surfactants, nonionic water-soluble polymers, cationic surfactants, and cationic water-soluble polymers can be used.

[0093] From the viewpoint of adhesion to the resin container, the content of thermoplastic resin particles in the coating layer is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more. The content of thermoplastic resin particles in the coating layer may be 90% by mass or less, or 85% by mass or less.

[0094] Furthermore, (meth)acrylic acid copolymers having polar groups exhibit good compatibility with PET resin, allowing for the molding of labeled containers without reducing the adhesion between the laminate and the PET resin container. From the viewpoint of adhesion, it is preferable that the (meth)acrylic acid copolymer has polar groups. The (meth)acrylic acid copolymer having polar groups may be anionic, cationic, or amphoteric, as long as it is polar. However, from the viewpoint of enhancing the effect of suppressing the reduction in adhesion of the heat seal layer, a (meth)acrylic acid copolymer having cationic groups is preferred, and a water-soluble (meth)acrylic acid copolymer having cationic groups is more preferable. If the (meth)acrylic acid copolymer having polar groups is water-soluble, the formation of the coating layer becomes easy by preparing a coating solution using an aqueous solvent and applying the coating solution. The (meth)acrylic acid copolymer having polar groups can be used together with, for example, ethyleneimine copolymers, water-soluble polymers having a quaternary ammonium salt structure or a phosphonium salt structure, vinyl polymers that have been cationized by modification of water-soluble polymers such as polyvinylpyrrolidone and polyvinyl alcohol. One or more of these can be used in combination.

[0095] Among (meth)acrylic acid copolymers having cationic groups, amino group-containing (meth)acrylic acid copolymers are preferred from the viewpoint of suppressing a decrease in adhesion.

[0096] In this specification, a cationic group is a group that acquires a positive charge when dissolved in water. A cationic group can be, for example, (A) a group that can bond with an anion to form a salt, or (B) a group that can bond with a proton to form a cation in the presence of an acid (e.g., acetic acid) and can bond with an acid anion. The group in (A) above can be, for example, an ammonium base or a phosphonium base together with an anion. The group in (B) above can be, for example, a nitrogen compound group such as an amino group.

[0097] An amino group is a group represented by the following formula (a), R 1 and R 2 Each of these can independently be a hydrogen atom, a C1-C3 alkyl group, or a C1-C3 alkenyl group, and the cationic group constituting the ammonium base is the group represented by the following formula (b), R 3 ~R 5 Each of these can independently be an alkyl group having 1 to 3 carbon atoms, or an alkenyl group having 1 to 3 carbon atoms. In this specification, R 1 and R 2 If both are hydrogen atoms, the group represented by the following formula (a) is a primary amino group, and R 1 and R 2 If either of the atoms is a hydrogen atom, the group represented by formula (a) below is a secondary amino group, and R 1 and R 2 If none of the atoms are hydrogen atoms, the group represented by formula (a) below shall be a tertiary amino group. The group represented by formula (b) below shall be a quaternary amino group. -NR 1 R 2 …(a) -N+R 3 R 4 R 5 …(b)

[0098] From the viewpoint of improving adhesion, the amino group-containing (meth)acrylic acid copolymer preferably has primary to tertiary amino groups, more preferably has secondary or tertiary amino groups, and even more preferably has tertiary amino groups. The "(meth)acrylic acid copolymer" in the "polar group-containing (meth)acrylic acid copolymer" contained in the coating layer can be different from the heat-sealable thermoplastic resin contained in the heat-seal layer. That is, the "polar group-containing (meth)acrylic acid copolymer" contained in the coating layer does not need to have heat-seal properties and may have a melting point of, for example, less than 60°C, -50 to 50°C, or -20 to 40°C, or may not have a melting point at all. The "polar group-containing (meth)acrylic acid copolymer" may not have a melting point. Furthermore, the "polar group-containing (meth)acrylic acid copolymer" may have a glass transition temperature of, for example, -50 to 70°C, -20 to 60°C, or 0 to 50°C.

[0099] The content of the (meth)acrylic acid copolymer having polar groups in the coating layer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of suppressing a decrease in adhesive strength. The content of the (meth)acrylic acid copolymer having polar groups in the coating layer is preferably 50% by mass or less, and more preferably 40% by mass or less, from the viewpoint of preventing blocking when the laminate and in-mold labels are stored stacked together.

[0100] The coating layer may contain other auxiliary components such as binders, antistatic agents, crosslinking accelerators, antiblocking agents, pH adjusters, and defoaming agents, to the extent that they do not impair the effects of the invention. Examples of binders include polyvinyl alcohol, polyvinylpyrrolidone, polyoxyalkylene derivatives, polyethyleneimine and its derivatives, polyacrylic acid copolymers, and urethane resins. Among these, polyethyleneimine or its derivatives are preferred. The content of each of these auxiliary components in the coating layer is preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, and particularly preferably 7% by mass or less. Furthermore, the total content of these auxiliary components in the coating layer is preferably 25% by mass or less, preferably 20% by mass or less, even more preferably 19% by mass or less, and particularly preferably 18% by mass or less. Furthermore, the coating layer preferably does not contain a silane coupling agent, and if it does contain a silane coupling agent, the content of the silane coupling agent is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.8% by mass or less, and particularly preferably 0.5% by mass or less. By the coating layer not containing a silane coupling agent, or by the low content of the silane coupling agent in the coating layer, the risk of the polar groups of the (meth)acrylic acid copolymer being crushed by silanol groups produced by hydrolysis is reduced, and its function is more easily exhibited.

[0101] From the viewpoint of improving adhesion and suppressing the decrease in adhesive strength, the thickness of the coating layer is preferably 0.01 μm or more, more preferably 0.03 μm or more, and even more preferably 0.1 μm or more. Furthermore, from the viewpoint of maintaining the adhesion of the heat seal layer and transparency, the thickness of the coating layer is preferably 7 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less.

[0102] (Method of manufacturing a laminate) The method for manufacturing the laminate is not particularly limited, but it can be manufactured by laminating a heat-seal layer onto one side of a base layer.

[0103] Methods for forming a single-layer substrate film include extrusion molding (cast molding) using a T-die, inflation molding using an O-die, and calendering using a rolling mill. Methods for forming a multilayer substrate film include supplying the thermoplastic resin composition to be used for each layer to different extruders for melting, supplying the thermoplastic resin composition discharged from each extruder to a T-die or O-die with a multilayer die configuration, and discharging it in a film form by lamination within the multilayer die. It is also possible to extrude and laminate a single-layer or multilayer sheet with a thermoplastic resin composition. With this method, it is also possible to use a paper substrate for the base layer.

[0104] Methods for laminating a heat seal layer to the other side of a substrate layer include co-extrusion, extrusion lamination, coating, and film lamination.

[0105] In the co-extrusion method, a thermoplastic composition for the base layer and a thermoplastic composition for the heat seal layer (there may be multiple of each) are supplied to a multilayer die, and the layers are laminated and extruded within the multilayer die, so lamination is performed simultaneously with molding.

[0106] In the extrusion lamination method, the base layer is first formed, then a molten thermoplastic composition for the heat seal layer is laminated onto it, and then nipped with a roll while cooling. Therefore, the forming and lamination are performed as separate processes.

[0107] In the film lamination method, the base layer and the heat-seal layer are each formed as separate films, and then bonded together using a pressure-sensitive adhesive. Therefore, the forming and lamination processes are performed separately.

[0108] The coating layer can be applied by coating on the heat-seal layer prepared by the method described above. Examples of coating methods include solvent coating and water-based coating. Among these methods, co-extrusion is preferred from the viewpoint of ensuring strong adhesion between each layer.

[0109] The base layer or heat seal layer may be an unstretched film or a stretched film.

[0110] Examples of stretching methods include 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.

[0111] The base layer and the heat seal layer may be stretched individually before lamination, or they may be stretched together after lamination. Alternatively, the stretched layers may be stretched again after lamination.

[0112] When stretching is performed, the stretching temperature is preferably in a range above the glass transition temperature of the thermoplastic resin used in each layer if the thermoplastic resin is amorphous. If the thermoplastic resin is crystalline, 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.

[0113] The stretching speed of the thermoplastic resin film is not particularly limited, but from the viewpoint of stable stretch molding, it is preferably in the range of 20 to 350 m / min.

[0114] Furthermore, the stretching ratio when stretching a thermoplastic resin film can be appropriately determined considering the characteristics of the thermoplastic resin used. For example, when stretching a thermoplastic resin film containing a propylene homopolymer or copolymer thereof in one direction, the stretching ratio is usually about 1.2 times or more, preferably 2 times or more, while it is usually 12 times or less, preferably 10 times or less. In the case of biaxial stretching, the stretching ratio 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, in terms of area stretching ratio.

[0115] Within the above stretching ratio range, it is easier to impart mechanical strength to the laminate and obtain resilience against shrinkage of the resin container during high-temperature immersion, thus improving the label separation rate. In addition, the thermoplastic resin film is less prone to breakage, and stable stretch molding tends to be possible.

[0116] A coating layer is provided on the outermost surface of the other side of the substrate layer by applying a coating liquid for the coating layer onto a heat-seal layer laminated on the substrate layer. Coating methods include printing and coating. The coating liquid can be prepared by dissolving or dispersing each component of the coating layer, such as thermoplastic resin particles and a polar (meth)acrylic acid copolymer, in a solvent. If the thermoplastic resin particles are water-dispersible and the polar (meth)acrylic acid copolymer is water-soluble, a water-dispersible and water-soluble coating liquid can be prepared using an aqueous solvent. This facilitates process control and is preferable from a safety standpoint. The aqueous solvent may mainly consist of water and may also contain water-soluble organic solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, toluene, and xylene. "Mainly consisting of water" means that 50% or more by mass of the total is water.

[0117] The coating of the coating solution and the drying of the coating film may be performed in-line with the formation of the substrate layer, or off-line. The amount of coating solution applied can be adjusted as appropriate, taking into account the thickness of the coated layer after drying, the concentration of the contained components, etc. For coating, coating equipment such as die coaters, bar coaters, roll coaters, lip coaters, gravure coaters, spray coaters, blade coaters, reverse coaters, and air knife coaters can be used. For drying, drying equipment such as hot air blowers and infrared dryers can be used.

[0118] The manufacturing method for in-mold labels is not particularly limited, but they can be manufactured by laminating a printed layer and a protective layer on the side of the laminate opposite to the heat-sealed layer. A printed layer can be provided on the side of the substrate layer of the laminate opposite to the heat-sealed layer by printing. Examples of printed information include product names, logos, manufacturer names, sales company names, usage instructions, and barcodes.

[0119] Printing methods include, for example, gravure printing, offset printing, flexographic printing, label printing, and screen printing.

[0120] If necessary, other layers besides the printed layer, such as a pattern layer, are provided, and then a protective coating liquid is applied to provide a protective layer on the outermost surface of one side of the substrate layer. In particular, providing the protective layer by printing, similar to the printed layer described above, is preferable because it simplifies the process and allows for easy selection of protective layer materials from commercially available products. Alternatively, another layer may be provided between the substrate layer and the heat seal layer.

[0121] (Labeling) The laminate of the present invention and the in-mold labels using the same are processed into the required shape and dimensions by cutting or die-cutting. Cutting or die-cutting can be performed before printing, but it is preferable to perform it after printing for ease of processing.

[0122] The thickness of the in-mold label is preferably 25 μm or more, and more preferably 45 μm or more, from the viewpoint of suppressing wrinkles in the label. Furthermore, from the viewpoint of providing transparency while suppressing the reduction in strength due to the thinning of the container at the label boundary when the in-mold label is applied to the container, the thickness is preferably 200 μm or less, and more preferably 150 μm or less.

[0123] (Containers with in-mold labels) An in-mold labeled container is a resin container on which the in-mold label of the present invention described above is provided on the surface. In the laminate of the present invention, a polyolefin resin film, which is inexpensive and has excellent moldability and mechanical strength, can be suitably used as the base layer. However, since a thermoplastic resin film having a melting point in a specific range depending on the molding temperature of stretch blow molding is used as the heat seal layer, the laminate exhibits high adhesion even to PET resin, which may be different from the base layer, and is an optimized label for PET resin containers that are stretch blow molded. However, since the heat seal layer of the laminate of the present invention also exhibits high adhesion in direct blow molding, it can also be used for polyethylene resin containers and polypropylene resin containers other than PET resin containers.

[0124] (Container material) As described above, the laminate of the present invention has high adhesion to PET resin and is optimized as a laminate for PET resin containers. However, it also exhibits good adhesion to polyethylene resins other than PET resin, polypropylene resins, etc., and the material of the container is not particularly limited.

[0125] In particular, laminates in which the heat-seal layer has a polar resin layer on its surface can be used for polar resin containers made of polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polybutylene succinate, and polylactic acid. Other polar resin containers that can be used include polycarbonate resins, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, and methyl methacrylate-styrene (MS) resin, as they have a similar bonding mechanism to polyester resins.

[0126] The container may be transparent or a natural color that does not contain colorants such as pigments or dyes, or it may be an opaque color produced by colorants or coloring agents.

[0127] The cross-sectional shape of the container body may be a perfect circle, an ellipse, or a rectangle. If the cross-sectional shape of the body is rectangular, it is preferable that the corners have curvature. From the viewpoint of strength, it is preferable that the cross-section of the body be a perfect circle or an ellipse close to a perfect circle, and more preferably a perfect circle.

[0128] (Manufacturing method for in-mold labeled containers) (In-mold molding) The method for manufacturing a container with an in-mold label is not particularly limited, as long as the in-mold label can be provided on the surface of the resin container during the in-mold molding of the resin container.

[0129] Suitable in-mold molding methods for using the laminate of the present invention include stretch blow molding, direct blow molding, injection molding, and differential pressure molding. As described above, the in-mold label of the present invention exhibits high adhesion to stretch blow molded products, and is particularly excellent in adhesion to PET resin containers. Furthermore, the in-mold label is easily peeled off the resin container during the high-temperature immersion process in recycling.

[0130] (Characteristics of laminates and in-mold labeled containers) As described above, a labeled container is obtained in which an in-mold label is attached to the surface of the container. The in-mold labeled container preferably has the following characteristics.

[0131] (Average particle size) In the laminate of the present invention, the thermoplastic resin particles contained in the coating layer preferably have an average particle diameter of 0.01 to 0.80 μm, from the viewpoint of providing adhesion between the resin container and the label, and from the viewpoint of providing transparency to the laminate. This can be measured using a laser diffraction particle size distribution analyzer. The average particle diameter of the thermoplastic resin particles can also be determined by observing the surface of the coating layer with an electron microscope, measuring the maximum diameter of at least 10 particles, and taking the average value.

[0132] (Haze value) From the viewpoint of aesthetics, the haze value of the laminate of the present invention is preferably 60% or less, and more preferably 55% or less. The haze value is measured in accordance with JIS-K-7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NDH2000).

[0133] (Percentage change in area and dimensions) Preferably, the absolute value of the area-dimensional change rate of the laminate of the present invention at a temperature of 80°C is 1% or less. The smaller the area-dimensional change rate, the more likely stress is to occur between the laminate and the easily shrinking resin container, making it easier for the label to peel off the resin container during high-temperature immersion treatment. Similarly, from the viewpoint of making it easier to peel off the in-mold label during recycling, preferably, the absolute value of the area-dimensional change rate of the laminate of the present invention at a temperature of 90°C is also 1% or less. The method for calculating the rate of change in area dimensions will be explained in the section on examples.

[0134] (Tackling power) The tack force of the laminate of the present invention at a temperature of 80°C is 0.8 N / cm 2 The following, preferably 0.75 N / cm² 2 More preferably, 0.7 N / cm 2 More preferably, 0.65 N / cm 2The following is particularly preferred: 0.6 N / cm 2 The following applies: The lower the tack force at 80°C, the easier it is for the laminate and in-mold label to peel off from the resin container during high-temperature immersion treatment, making the resin container easier to recycle. An example of this tack force is 0.01 N / cm². 2 That's all.

[0135] Similarly, from the viewpoint of making the laminate and in-mold label easier to peel off during recycling, the tack force of the laminate of the present invention at a temperature of 90°C is 1.2 N / cm 2 Preferably less than 1 N / cm 2 The following is more preferable: The tack force is, for example, 0.6 N / cm. 2 That's all. On the other hand, from the viewpoint of ensuring sufficient adhesion of the in-mold label to the resin container during in-mold molding, the tack force of the laminate of the present invention at a temperature of 100°C is 1.2 N / cm. 2 The above is preferable, for example, 8 N / cm 2 The following applies: The method for calculating tack force will be explained in the section on examples.

[0136] (Melting rate) In the laminate of the present invention, the melting rate of the heat seal layer at a temperature of 80°C is preferably 80% or less, more preferably 75% or less, even more preferably 70% or less, and particularly preferably 65% ​​or less. A melting rate of 80% or less makes it easier to keep the tack force low at the temperature during high-temperature immersion treatment. The melting rate at 80°C is, for example, 1% or more.

[0137] Similarly, from the viewpoint of keeping the tack force low, the melting rate of the heat seal layer at a temperature of 90°C is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less. The melting rate at 90°C is, for example, 60% or more.

[0138] On the other hand, from the viewpoint of ensuring sufficient adhesion of the laminate to the resin container, the melting rate of the heat seal layer at a temperature of 100°C is preferably 70% or more, more preferably 75% or more, even more preferably 80% or more, and particularly preferably 85% or more. The melting rate at 100°C is, for example, 100% or less. Furthermore, if the laminate comprises multiple heat-seal layers, it is preferable that the outermost heat-seal layer (opposite the base layer) has the above-mentioned melting rate.

[0139] (Fusion heat rate) In the laminate of the present invention, the heat of fusion rate of the heat seal layer at a temperature of 80°C is preferably 80% or less, more preferably 75% or less, even more preferably 70% or less, and particularly preferably 65% ​​or less. If the heat of fusion rate is 80% or less, it is easier to keep the tack force low at the temperature during high-temperature immersion treatment. The heat of fusion rate at 80°C is, for example, 1% or more. The above heat of fusion rate is measured by DSC.

[0140] (Adhesive strength) From the viewpoint of suppressing peeling from the resin container under normal use conditions, the adhesive strength of the laminate of the present invention to the resin container is preferably 200 gf / 15 mm or more, more preferably 300 gf / 15 mm or more, and even more preferably 350 gf / 15 mm or more. From the viewpoint of easily peeling from the resin container during high-temperature immersion treatment, the above adhesive strength may be 600 gf / 15 mm or less, and may be 450 gf / 15 mm or less.

[0141] The method for calculating adhesive strength will be explained in the section on examples.

[0142] (Label separation rate) From the viewpoint of separation effectiveness, the label separation rate of the laminate of the present invention at 80°C is preferably 40% or more. More preferably, it is 100%. The method for calculating the label separation rate will be explained in the section on examples. [Examples]

[0143] 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.

[0144] (Manufacturing Example 1) 40 kg of isopropanol (Tokuyama Corporation, product name: Tokuso IPA) was charged into a 150 L reactor equipped with a reflux condenser, nitrogen inlet tube, lifter, thermometer, dropping funnel, and heating jacket. While stirring, 12.6 kg of N,N-dimethylaminoethyl methacrylate (Sanyo Chemical Industries, product name: Methacrylate DMA), 12.6 kg of butyl methacrylate (Mitsubishi Rayon Corporation, product name: Acryester B), and 2.8 kg of higher alcohol methacrylate (Mitsubishi Rayon Corporation, product name: Acryester SL, a mixture of lauryl methacrylate and tridecyl methacrylate) were introduced into the reactor. Next, nitrogen was purged from the system, and the temperature inside the reactor was raised to 80°C. Then, 0.3 kg of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd., product name: V-60(AIBN)) was introduced into the reactor as a polymerization initiator.

[0145] The copolymerization reaction was carried out by continuously stirring the reactor for 4 hours while maintaining the temperature at 80°C. After cooling to room temperature, the resulting copolymer was neutralized by introducing 4.3 kg of glacial acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) into the reactor. Next, isopropanol was removed by distillation while introducing 48.3 kg of ion-exchanged water into the reactor, replacing the system with an aqueous system, and a viscous aqueous solution (solid content concentration 35% by mass) of a methacrylic acid copolymer (with no melting point, weight-average molecular weight 40,000) having a tertiary amino group as a polar group in its side chain was obtained. Furthermore, since the obtained methacrylic acid copolymer bonded with protons in the aqueous solution and bonded with acetate ions as cations, it was confirmed that the polar group is a cationic group.

[0146] (Manufacturing example 2) 96.7 parts by mass of OP varnish (manufactured by T&K TOKA, product name: L-carton OP varnish KS), 3 parts by mass of silicone main agent (manufactured by T&K TOKA, product name: UV-reactive silicone A), and 0.3 parts by mass of silicone auxiliary agent (manufactured by T&K TOKA, product name: UV-reactive silicone B) were mixed to obtain a coating liquid for a protective layer containing silicone.

[0147] (Example 1) <Manufacturing of in-mold labels> As a material for the base layer, a thermoplastic resin (a1) made of a thermoplastic resin (propylene homopolymer (product name: Novatec PP FY4, manufactured by Nippon Polypropylene Co., Ltd., MFR (230℃, 2.16kg load): 5g / 10min, melting point: 167℃)) was prepared. Furthermore, as a material for the heat seal layer, thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³) is used. 3 )) 70% by mass, and thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³) 3 ))30% by mass was mixed to prepare thermoplastic resin (b1). Furthermore, as the material (solid content) for the coating layer, a dispersion of thermoplastic resin particles (ethylene-methacrylic acid copolymer (EMAA) (melting point: 90°C, average particle size: 0.07 μm)) (80% by mass in terms of solid content) and 20% by mass of the methacrylic acid copolymer (acrylic copolymer with polar groups (melting point: none)) obtained in Production Example 1 were mixed to prepare thermoplastic resin (c1). A thermoplastic resin composition (a1) was melt-kneaded in an extruder set to 230°C, then supplied to an extrusion die set to 250°C and extruded into a sheet. Next, it was cooled using a cooling device, and the resulting unstretched sheet was heated to 140°C and stretched four times in the MD direction to obtain a four-fold stretched film. Next, the thermoplastic resin (b1) was melt-kneaded in another extruder set to 230°C, then co-extruded into a sheet and laminated onto the above 4x stretched film. This resulted in a laminated film with a two-layer structure of a 4x stretched film / thermoplastic resin composition (b1). The laminated film was cooled to 60°C and then reheated to approximately 140°C using a tenter oven and stretched 10 times in the TD direction. After heat treatment in a heat setting zone adjusted to 160°C, it was cooled to 60°C and the edges were slit. Meanwhile, a resin composition (c1) for forming a coating layer was applied to the stretched resin composition (b1) using a bar coater as a coating liquid. Next, it was dried in a 10m long oven at a drying temperature set to 80°C. This resulted in the laminate of Example 1 having a three-layer structure (composition: a1 / b1 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer are stacked in this order, and a total thickness of 80.15 μm.

[0148] <Manufacturing of labeled containers> The above laminate was cut into single sheets and punched out into 8cm x 6cm rectangles to create evaluation samples. These samples were charged using an electrostatic charging device and placed inside the molding die of a stretch blow molding machine (Nissei ASB Co., Ltd., machine name: ASB-12M) and clamped. At this time, the laminate was positioned so that the base layer was in contact with the die (so that the coating layer faced the cavity side). The laminate was also positioned so that the long side of the label was parallel to the circumferential direction of the body of the resin container within the die. The die was controlled so that the surface temperature on the cavity side was within the range of 20 to 45°C.

[0149] Subsequently, labeled containers were molded under the following molding conditions. <Molding conditions> A polyethylene terephthalate resin preform was preheated to 98°C and introduced into a mold, where it was stretch blow molded for 6 seconds under a blow pressure of 3.2 MPa. After cooling to 50°C in 5.5 seconds, the mold was opened to obtain a labeled container 20 having a rectangular body 21, as shown in Figures 4A and 4B. The horizontal dimension 20W of the body was 145 mm, the depth dimension 20L was 72.5 mm, and the height dimension 20H was 130 mm. Dimension 20H was measured from the bottom surface to the bottom edge of the cap opening 22.

[0150] The stretching ratio of the labeled container 20 was 1.2 times in the horizontal direction W, 2.6 times in the depth direction L, and 1.8 times in the height direction H. The stretching ratio was determined as the ratio of the dimensions 20W, 20L, and 20H of the labeled container 20 to the dimensions of the preform in the horizontal direction W, depth direction L, and height direction H. Since the body 21 of the labeled container bulges out from the bottom, the dimensions 20W and 20L were measured at different positions in the height direction H, and the average value of each measurement was adopted.

[0151] (Example 2) As the material for the coating layer of Example 1, the dispersion of thermoplastic resin particles was changed to that of thermoplastic resin particles (ethylene-methacrylic acid copolymer (EMAA) (melting point: 90°C, average particle size: 0.5 μm)), and a thermoplastic resin (c2) was prepared by the same procedure. Furthermore, by performing the same procedure as in Example 1, a laminate of Example 2 was obtained having a three-layer structure (composition: a1 / b1 / c2, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) and a total thickness of 80.15 μm, in which the base layer / heat seal layer / coat layer were laminated in this order, and a labeled container was formed by performing the same procedure as in Example 1.

[0152] (Example 3) As the material for the coating layer in Example 1, the dispersion of thermoplastic resin particles was changed to that of thermoplastic resin particles (ethylene-methacrylic acid copolymer (EMAA) (melting point: 90°C, average particle size: 0.7 μm)), and a thermoplastic resin (c3) was prepared by the same procedure. Furthermore, by performing the same procedure as in Example 1, a laminate of Example 3 was obtained having a three-layer structure (composition: a1 / b1 / c3, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) and a total thickness of 80.15 μm, in which the base layer / heat seal layer / coat layer were laminated in this order, and a labeled container was formed by performing the same procedure as in Example 1.

[0153] (Example 4) The material used for the heat seal layer in Example 1 was a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³)). 3 A thermoplastic resin (b2) was prepared using 100% by mass. Otherwise, by the same procedure as in Example 1, a laminate of Example 4 was obtained having a three-layer structure (composition: a1 / b2 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm, and a labeled container was formed by the same procedure as in Example 1.

[0154] (Example 5) The material used for the heat seal layer in Example 1 was a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³)). 3 ))90% by mass, and thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³) 3 ))10% by mass was mixed to prepare thermoplastic resin (b3). Otherwise, by the same procedure as in Example 1, a laminate of Example 5 was obtained having a three-layer structure (composition: a1 / b3 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of drawing axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm, and a labeled container was formed by the same procedure as in Example 1.

[0155] (Example 6) The material used for the heat seal layer in Example 1 was a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³)). 3 )) 50% by mass, and thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³) 3 50% by mass of the mixture was prepared to create thermoplastic resin (b4). Otherwise, by the same procedure as in Example 1, a laminate of Example 6 was obtained with a three-layer structure (composition: a1 / b4 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of drawing axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm was obtained, and a labeled container was formed by the same procedure as in Example 1.

[0156] (Example 7) The material used for the heat seal layer in Example 1 was a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³)). 3 )) 30% by mass, and thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³) 3 ))70% by mass was mixed to prepare thermoplastic resin (b5). Otherwise, by the same procedure as in Example 1, a laminate of Example 7 was obtained having a three-layer structure (composition: a1 / b5 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of drawing axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm. A labeled container was then formed by the same procedure as in Example 1.

[0157] (Example 8) The material used for the heat seal layer in Example 1 was a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³)). 3 )) 10% by mass, and thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³) 3 ))90% by mass was mixed to prepare thermoplastic resin (b6). Otherwise, by the same procedure as in Example 1, a laminate of Example 8 was obtained with a three-layer structure (composition: a1 / b6 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of drawing axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm was obtained, and a labeled container was formed by the same procedure as in Example 1.

[0158] (Example 9) The material used for the heat seal layer in Example 1 was a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³)). 3 )) 100% by mass was mixed to prepare thermoplastic resin (b7). Otherwise, by the same procedure as in Example 1, a laminate of Example 9 was obtained with a three-layer structure (composition: a1 / b7 / c1, thickness: 75 μm / 5 μm / 0.15 μm, number of drawing axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm was obtained, and a labeled container was formed by the same procedure as in Example 1.

[0159] (Example 10) The material for the first heat seal layer is a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³)). 3 )) 100% by mass was mixed to prepare thermoplastic resin (b8). The material for the second heat seal layer is a thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8402, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 30g / 10min, melting point: 97℃, density: 0.902g / cm³)). 3 )) 70% by mass, and thermoplastic resin (metallocene catalyst polyethylene (product name: Engage8401, manufactured by Dow Chemical, MFR (190℃, 2.16kg load): 31g / 10min, melting point: 79℃, density: 0.885g / cm³) 3 ))30% by mass was mixed to prepare thermoplastic resin (b9). Next, resin composition (b8) and resin composition (b9) were melt-kneaded in extruders set to 230°C, respectively, and then supplied to a multilayer die set to 250°C for lamination inside the die. The mixture was then co-extruded into a sheet onto the 4x stretched film obtained in Example 1 to obtain a laminated film with a three-layer structure of a base layer, a first heat-seal layer, and a second heat-seal layer. The laminated film was cooled to 60°C, heated again to approximately 140°C using a tenter oven, and stretched 10 times in the TD direction. After heat treatment in a heat-setting zone adjusted to 160°C, it was cooled to 60°C and the edges were slit. Meanwhile, a resin composition (c1) for forming the coating layer was applied to the stretched resin composition (b9) using a bar coater as a coating liquid. Next, it was dried in a 10m long oven at a drying temperature of 80°C. As a result, the base layer / first heat seal layer / second heat seal layer / coat layer are laminated in this order. 4 layersA laminate of Example 10 was obtained having a structure (composition: a1 / b8 / b9 / c1, thickness: 75 μm / 2 μm / 3 μm / 0.15 μm, number of drawing axes: 2 axes / 1 axis / 1 axis / -) and a total thickness of 80.15 μm.

[0160] (Comparative Example 1) In Example 1, the thermoplastic resin particles were replaced with thermoplastic resin particles (ethylene-methacrylic acid copolymer (EMAA) dispersion (melting point: 90°C, average particle size: 1.0 μm)) and a thermoplastic resin (c4) was prepared by the same procedure. Furthermore, by performing the same procedure as in Example 1, a laminate of Comparative Example 1 was obtained with a three-layer structure (composition: a1 / b1 / c4, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were laminated in this order, and a total thickness of 80.15 μm was obtained, and a labeled container was formed by performing the same procedure as in Example 1.

[0161] (Comparative Example 2) As the material for the coating layer in Example 1, a thermoplastic resin (c5) was prepared, consisting of a methacrylic acid-based copolymer (acrylic copolymer with polar groups (melting point: none)) obtained in Production Example 1. Furthermore, by performing the same procedure as in Example 1, a laminate of Comparative Example 2 was obtained having a three-layer structure (composition: a1 / b1 / c5, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) in which the base layer / heat seal layer / coat layer were stacked in this order, and a total thickness of 80.15 μm. A labeled container was then formed by performing the same procedure as in Example 1.

[0162] (Comparative Example 3) As the material for the coating layer in Example 1, a thermoplastic resin (c6) consisting of a dispersion of thermoplastic resin particles (ethylene-methacrylic acid copolymer (EMAA) (melting point: 90°C, average particle size: 0.07 μm)) was prepared. Furthermore, by performing the same procedure as in Example 1, a laminate of Comparative Example 3 was obtained having a three-layer structure (composition: a1 / b1 / c6, thickness: 75 μm / 5 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis / -) and a total thickness of 80.15 μm, in which the base layer / heat seal layer / coat layer were laminated in this order, and a labeled container was formed by performing the same procedure as in Example 1.

[0163] (Comparative Example 4) In Example 1, without creating a coating layer, a laminate of Comparative Example 4 was obtained by performing the same procedure as in Example 1, with a two-layer structure (composition: a1 / b1, thickness: 75 μm / 0.15 μm, number of stretch axes: 2 axes / 1 axis) in which a base layer / heat seal layer was laminated, and a total thickness of 80 μm was obtained. A labeled container was then formed by performing the same procedure as in Example 1.

[0164] (raw materials) Table 1 shows a list of the raw materials used in each example and comparative example. [Table 1]

[0165] (Evaluation method) <Thickness> The total thickness of the laminate was measured in accordance with JIS K7130:1999 using a constant-pressure thickness gauge (product name: PG-01J, manufactured by Teclock Co., Ltd.). The thickness of each layer in the laminate was determined as follows: The sample to be measured was cooled to a temperature of -60°C or lower using liquid nitrogen, and a razor blade (product name: Proline Blade, manufactured by Schick Japan Co., Ltd.) was applied at a right angle to the sample placed on a glass plate to cut it and prepare a sample for cross-sectional observation. The cross-section of the obtained sample was observed using a scanning electron microscope (product name: JSM-6490, manufactured by JEOL Ltd.), and the boundary lines for each thermoplastic resin composition of each layer were identified from the appearance, and the total thickness of the laminate was multiplied by the thickness ratio of each observed layer to determine the total thickness.

[0166] <Average particle size of thermoplastic resin particles> The average particle size of thermoplastic resin particles was determined by observing the surface of the coating layer with an electron microscope, measuring the maximum diameter (diameter of the circumscribed circle) of 10 particles, and taking the average value.

[0167] <Percentage change in area and dimension of laminated material> A sample was prepared by cutting out a section of the laminate so that its length in the MD direction was 50 mm and its length in the TD direction was 5 mm. The prepared sample was placed inside a thermomechanical analyzer TMA7100 (manufactured by Hitachi High-Tech Science Corporation), and the sample was held with a fixing device so that the measurement piece was 15 mm inside the TMA7100. The sample was heated under the conditions of a temperature range of 0 to 120°C and a heating rate of 10°C / min while applying a load of 49 N. The dimension in the MD direction (D) at the temperature of 0°C before heating was measured. M 0) and the dimension in the MD direction after heating (D M 1) was measured. After heating, the dimensions were measured at temperatures of 80°C and 90°C. Similarly, using a sample cut from the laminate so that the length in the TD direction was 50 mm and the length in the MD direction was 5 mm, the dimensions in the TD direction (D) before and after heating were measured. T 0 and D T 1) was measured.

[0168] From the measured values ​​of each dimension, the area dimensional change rate K at temperatures of 80°C and 90°C can be calculated using the following formula. 10 The percentage change in area / dimension K was calculated. 10 (%) indicates a negative sign if the material contracts after heating, and a positive sign if it expands. Area dimensional change rate K 10 (%) = (D M 0×D T 0-D M 1×D T 1) / (D M 0×D T 0) × 100

[0169] <Melting rate of the heat seal layer> A 5 mg sample of the heat-seal layer was placed in a differential scanning calorimeter DSC7000X (manufactured by Hitachi High-Tech Science Corporation). Using this differential scanning calorimeter, a heating / cooling / heating cycle was performed at a scanning speed of 10 m / min in the temperature range of -60°C to 200°C to obtain a DSC curve. From the DSC curve of the second heating process, the heat of fusion for the entire heating process and the heat of fusion at each temperature of 80°C, 90°C, and 100°C were determined. The melting rate was calculated by dividing the heat of fusion at each temperature by the heat of fusion for the entire heating process.

[0170] <Fusion rate of the heat seal layer> The DSC curve was obtained in the same manner as described above. The total endothermic peak area S of the DSC curve for the second heating step. T The endothermic peak area S below 80°C was measured. 80 The following measurements were taken, and the heat of fusion rate at 80°C was calculated based on the formula below. Heat of fusion rate = S 80 / S T ×100

[0171] <Tackiness> A sample of the laminate was placed in a tacking test machine (TAC-II) (manufactured by REHSCA). Using this machine, a stainless steel probe with a diameter of φ5 mm, heated to a predetermined temperature, was pressed against the surface of the laminate that was in contact with the resin container with a load of 10 N for 30 seconds. After 1 minute, the tack force (N / cm) was measured when the laminate was peeled off at a peeling speed of 30 m / min. 2 ) was measured.

[0172] <Haze value> The haze value was measured in accordance with JIS-K-7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NDH2000).

[0173] <Percentage change in area and dimensions of resin containers> As shown in Figures 4A and 4B, the label on the body 21 of the labeled container 20 10 On the side opposite to the side to which the label is attached, 10A sample was prepared by cutting out a section of the same area as the area to which the material was attached, with a width of 50 mm in the horizontal direction (W) and a width of 5 mm in the vertical direction (H). Using this sample, the area dimensional change rate K of the laminate was determined. 10 Similarly, the horizontal dimension W at the temperature 0°C before heating (D W 0) and the horizontal dimension W after heating (D W 1) was measured. After heating, the dimensions were measured at 75°C, 80°C and 90°C. Similarly, using a sample cut from a labeled container 20 so that the vertical length H was 50 mm and the horizontal length W was 5 mm, the vertical dimension H (D) before and after heating was measured. H 0 and D H 1) was measured.

[0174] From the measured values ​​of each dimension, the area dimensional change rate K at temperatures of 75°C, 80°C, and 90°C can be calculated using the following formula. 30 The percentage change in area / dimension K was calculated. 30 (%) indicates a negative sign if the material contracts after heating, and a positive sign if it expands. Area dimensional change rate K 30 (%) = (D W 0×D H 0-D W 1×D H 1) / (D W 0×D H 0) × 100

[0175] <Label separation rate> For each example and comparative example, the label portion of the labeled container was cut off as a single unit from the label and the resin container using a cutter. The mass (Ta) of the cut-off labeled container was measured. The label portion was pulverized into flakes using a pulverizer (Morita Seiki Co., Ltd., product name: XL-15, mesh screen size 8 mmφ) to prepare a sample for evaluation. The sample was placed in a constant temperature water bath maintaining water temperatures of 75°C, 80°C, and 90°C, and immersed for 10 minutes while stirring. The sample was removed from the high-temperature water and thoroughly dried. Similarly, the sample was placed in a constant temperature water bath maintaining the temperature of an alkaline solution (sodium hydroxide solution) at 80°C and 90°C, and immersed for 10 minutes while stirring (high-temperature immersion process). After removing the sample from the high-temperature alkaline solution and neutralizing it, it was washed with water, and the label and resin container that had sunk in the water were recovered. The total mass (Tb) of the recovered label and resin container was measured. Subsequently, the label was completely peeled off the resin container, and the mass (B) of the remaining resin container was measured. The (specific gravity) separation rate (%) of the labels was calculated using the following formula, based on the mass of the labels before immersion and the mass of the labels that peeled off and were separated by specific gravity after immersion. Label separation rate (%) = (Ta - Tb) / (Ta - B) × 100

[0176] <Adhesion strength between resin containers and in-mold labels> A printed layer was created on the substrate layer side of the laminates obtained in the examples and comparative examples by printing a pattern including characters (MS Gothic, 6-20 points) using a flexographic printing press (MT Tech Co., Ltd., machine name: FC11B) and UV flexographic ink (T&K TOKA Co., Ltd., product name: Flexo 500). Furthermore, the protective coating solution obtained in Manufacturing Example 2 was applied to the printed layer using a gravure roll, and the protective coating solution was cured by irradiating it with 800 J of energy from a UV lamp to form a protective layer and obtain an in-mold label. The thickness of the cured protective layer was 2.5 μm.

[0177] The obtained in-mold labels were immediately cut into sheets and punched out into rectangles with a long side of 8 cm and a short side of 6 cm to prepare evaluation samples (A). Separately, the obtained in-mold labels were wound into a roll so that the surface of one outermost layer, the protective layer, and the surface of the other outermost layer, the coating layer, were in contact, and this was left to stand for 8 days in an environment of 25°C and 50% relative humidity. After that, the roll of in-mold labels was unwound and cut into sheets, and punched out into rectangles with a long side of 8 cm and a short side of 6 cm to prepare evaluation samples (B).

[0178] The punched in-mold labels were charged using an electrostatic charging device and then placed inside the molding die of a stretch blow molding machine (Nissei ASB Co., Ltd., machine name: ASB-70DPH) and clamped. The labels were placed so that the protective layer was in contact with the die (the coating layer facing the cavity side). The in-mold labels were placed in the die so that the long side of the label was parallel to the circumferential direction of the body of the resin container. The die was controlled so that the surface temperature on the cavity side was within the range of 20 to 45°C.

[0179] Meanwhile, a polyethylene terephthalate resin preform was preheated to 100°C. Next, the preform was guided into a mold and stretch-blow molded for 6 seconds under a blow pressure of 3.2 MPa. It was then cooled to 50°C in 5.5 seconds. Next, the mold was opened to obtain a labeled container with a rectangular body measuring 12 cm in height and approximately 7 cm on each side.

[0180] The resulting labeled containers were stored for two days at a temperature of 23°C and a relative humidity of 50%. Next, the label and the container body were cut together using a cutter, and a total of six measurement samples were taken from the two containers, each measuring 12 cm in length (8 cm with the label attached and 4 cm without) and 1.5 cm in width (the label was attached across the entire width), with the circumference of the container body as the longitudinal direction.

[0181] Next, the adhesive portion of the label was carefully peeled away from the non-adhesive portion, leaving a gap of approximately 1 cm to form a gripping area. Then, this gripping area was placed on top of a 1.5 cm wide PET film (50 μm thick) and bonded with adhesive to create the gripping area on the label side, and a sample for measuring adhesive strength was prepared.

[0182] In accordance with JIS K6854-2:1999, a 180-degree peel test was conducted between the container body and the label using a tensile testing machine (Shimadzu Corporation, model: Autograph AGS-5kNJ) at a peel speed of 300 mm / min. The average peel force over a peel length of 25 to 75 mm was measured, and the adhesive strength was defined as the average of the measurements from six samples. The unit of adhesive strength was N / 15 mm.

[0183] Tables 2 to 4 show the evaluation results. Note that in Tables 2 to 4, the water-soluble binder is simply referred to as "binder" for convenience. Furthermore, the porosity of the substrate layer in both the examples and comparative examples was 0%. [Table 2] [Table 3] [Table 4]

[0184] As shown in Tables 2 and 4, in Examples 1 to 10, even with the migration of silicone from the protective layer, the adhesive strength between the in-mold label and the container was sufficient, and the haze value was 60 or less. Thus, the objective of providing a laminate that enhances the adhesion between the in-mold label and the container while also being transparent was achieved.

[0185] On the other hand, as shown in Table 3, in Comparative Example 1, the average particle size of the thermoplastic resin particles contained in the coating layer was greater than 0.8 μm, resulting in an increased haze value, increased opacity, and a deterioration in aesthetics. In Comparative Example 2, the coating layer did not contain thermoplastic resin particles themselves, but only (meth)acrylic acid copolymer, resulting in reduced adhesion strength to the container. In Comparative Example 3, the coating layer contained thermoplastic resin particles but did not contain (meth)acrylic acid copolymer, resulting in reduced adhesion strength to the container. Furthermore, in Comparative Example 4, there was no coating layer, resulting in the lowest adhesion strength.

[0186] From the above, it has become clear that a laminate comprising a base layer, a heat seal layer, and a coating layer, wherein the coating layer contains thermoplastic resin particles and a (meth)acrylic acid copolymer, the thermoplastic resin particles have an average particle size of 0.01 to 0.80 μm, and the (meth)acrylic acid copolymer has polar groups, provides a laminate that adheres to a resin container and is also transparent.

[0187] This application claims priority based on Japanese Patent Application No. 2023-027072, filed on February 24, 2023, and incorporates all the contents of said Japanese Patent Application. [Explanation of symbols]

[0188] 1. Laminate 2 Base material layer 4. Heat seal layer 6 coat layers

Claims

1. A laminate comprising a base layer, a heat seal layer, and a coating layer, The coating layer comprises thermoplastic resin particles and a (meth)acrylic acid-based copolymer. The thermoplastic resin particles have an average particle diameter of 0.07 to 0.7 μm. The (meth)acrylic acid copolymer has polar groups, Laminated structure.

2. The laminate according to claim 1, wherein the average particle size of the thermoplastic resin particles is 0.07 to 0.45 μm.

3. The laminate according to claim 1 or 2, wherein the haze value is 60% or less.

4. The laminate according to claim 1 or 2, wherein the (meth)acrylic acid copolymer has primary to tertiary amino groups.

5. The laminate according to claim 1 or 2, wherein the (meth)acrylic acid copolymer has a melting point of less than 60°C or does not have a melting point.

6. This is a laminate used by bonding it to a resin container that is a stretch blow molded body. The absolute value of the area-dimensional change rate at 80°C is 1% or less. The tack force at 80°C is 0.8 N / cm. ２ The following is The laminate according to claim 1.

7. The tack force at 90°C is 1.2 N / cm. ２ The laminate according to claim 6, which is less than [amount missing].

8. The laminate according to claim 6 or 7, wherein the heat of fusion rate of the heat-sealing resin of the heat-sealing layer at 80°C is 80% or less.

9. The heat seal layer comprises a first heat seal resin and a second heat seal resin, The melting point of the first heat seal resin is 75 to 85°C. The melting point of the second heat-seal resin is 95 to 105°C. The laminate according to claim 6 or 7.

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