Laminate

Abstract

The purpose of the present invention is to provide a laminate that can maintain an adhesive strength resistant to easy peeling from a molding during use, that at the same time enables the affixed laminate to be separated from a molding during recycling, and that is resistant to blistering.　The present invention relates to a laminate comprising a porous resin layer and an uneven layer provided on one of the main surfaces of the porous resin layer, wherein the porous resin layer contains a filler; the content of this filler is 40 mass% to 70 mass%; the uneven layer contains a thermoplastic resin; the thermoplastic resin in the uneven layer contains a polyethylene-based resin (A) having a melting point of 80 to 140°C; and the content of the polyethylene-based resin (A) in the thermoplastic resin is at least 40 mass%.

Description

Laminate

[0001] The present invention relates to a laminate.

[0002] Laminates such as labels are attached to molded articles to display product names, contents, and the like. In-mold molding is a known method for attaching a laminate to a molded article. In-mold molding involves pouring a parison (molten molding resin) molten at high temperature into a mold and then cooling it to form a molded article according to the shape of the mold. By placing a laminate such as a label in the mold, a molded article with a molten label attached can be produced using the heat of the heated molding resin. Such molded articles with a laminate typically require high adhesion (adhesion strength) between the laminate and the molded article. For example, Patent Document 1 discusses resin materials for use in a heat-sealable resin layer in a laminate to achieve good adhesion to polyethylene or polypropylene resin containers (molded articles).

[0003] On the other hand, when recycling plastics from the viewpoint of environmental protection, properties opposite to high adhesion between the laminate and the molded product are also required. For example, when recycling a resin container (molded product) to which a shrink label (laminate) is attached, the shrink label is mechanically peeled off from the resin container in the process of crushing the used resin container, and the resin container after peeling is recycled.

[0004] Japanese Patent Application Laid-Open No. 2006-69674

[0005] Thus, in order to obtain a high adhesive strength between the laminate and the molded body, it has been considered to bond the molded body to the main surface of the laminate on the side of the heat-sealable resin layer that can be sufficiently melted by the heat of the heated molding resin, as in Patent Document 1. On the other hand, if the adhesion between the laminate and the molded body is strong as in Patent Document 1, it tends to be difficult to mechanically peel the laminate during a crushing process or the like when recycling after use.

[0006] Furthermore, when molding a laminate and a molded body, defects such as lifting or swelling due to insufficient adhesive strength or trapped air during molding may occur, known as blisters. In this regard, when the adhesion between the laminate and the molded body is adjusted to facilitate peeling during recycling, blisters tend to occur easily during molding. These blisters tend to cause swelling or lifting, particularly when the molded body or laminate is large.

[0007] Therefore, an object of the present invention is to provide a laminate that can be separated from a molded article when it is attached and that is less likely to develop blisters when recycled.

[0008] The present inventors have conducted extensive research to solve the above problems and have come up with the following invention.

[0009] That is, the present invention is as follows. [1] A laminate comprising a porous resin layer and a concave-convex layer provided on either main surface of the porous resin layer, wherein the porous resin layer contains a filler, the content of the filler being 40% by mass or more and 70% by mass or less, the concave-convex layer containing a thermoplastic resin, the thermoplastic resin of the concave-convex layer containing a polyethylene-based resin (A) having a melting point of 80 to 140°C, and the content of the polyethylene-based resin (A) in the thermoplastic resin being 40% by mass or more. [2] The laminate according to [1], wherein the smoothness of the surface on the concave-convex layer side is 10 to 150 seconds. [3] The laminate according to [1] or [2], wherein the porosity of the concave-convex layer is 30% or less. [4] The laminate according to any of [1] to [3], wherein the concave-convex layer further contains a polypropylene-based resin (B). [5] The laminate according to any one of [1] to [4], further comprising a second porous resin layer, the second porous resin layer being laminated on a main surface of the porous resin layer opposite the concave-convex layer, and the porosity of the second porous resin layer being 25 to 60%.

[0010] According to the present invention, it is possible to provide a laminate that can be separated from a molded article when it is attached and that is less likely to develop blisters during recycling.

[0011] Fig. 1 is a schematic cross-sectional view showing an example of a laminate according to an embodiment; Fig. 2 is a schematic cross-sectional view showing another example of a laminate according to an embodiment; Fig. 3 is a schematic cross-sectional view showing an example of a laminate according to an embodiment; Fig. 4 is a schematic front view showing an example of a laminate according to an embodiment.

[0012] The present invention will be described in detail below with reference to the following embodiments. Note that the embodiments are merely examples of the present invention, and the present invention is not limited to these embodiments.

[0013] To solve the above problems, the present inventors conducted extensive research into a laminate that suppresses the occurrence of blisters due to insufficient adhesive strength, while providing peelability that allows for easy separation from a molded body during recycling. Conventionally, laminates have been known that enhance adhesion to a molded body by, for example, applying a low-melting-point resin to a heat-sealable layer and sufficiently melting the heat-sealable layer using the heat of the heated molding resin. However, in this case, the pursuit of high adhesion tends to make it difficult to create a laminate that is easy to peel during recycling. Therefore, the present inventors conducted extensive research into a laminate that combines the opposing directional characteristics of maintaining adhesion while also providing easy peelability during recycling. As a result, the present inventors came up with the laminate of the present embodiment, which has a textured layer on the side that is attached to the molded body during molding, and a porous resin layer containing a predetermined amount of filler.

[0014] [Laminate] The laminate comprises a porous resin layer and a concave-convex layer provided on one of the main surfaces of the porous resin layer. The porous resin layer contains a filler, and the content of the filler in the porous resin layer is 40% by mass or more and 70% by mass or less. The concave-convex layer contains a thermoplastic resin, and the thermoplastic resin of the concave-convex layer contains a polyethylene-based resin (A) having a melting point of 80 to 140°C. The content of the polyethylene-based resin (A) in the thermoplastic resin is 40% by mass or more.

[0015] The laminate of this embodiment comprises the porous resin layer and the uneven layer described above. When attached to a molded body via the uneven layer, the laminate maintains adhesion to the molded body while being easily mechanically separated from the molded body during the crushing process in recycling. The laminate of this embodiment has an uneven layer containing a certain amount of polyethylene-based resin (A). The uneven layer is, for example, provided in a pattern. The presence of such an uneven layer contributes to improving adhesion to the molded body while suppressing excessive adhesion. Furthermore, by providing the laminate with a porous resin layer containing a filler in an amount of 40% by mass or more, the porous resin layer can be made brittle, which can also promote peeling from the brittle porous resin layer during the crushing process in recycling. This makes it easier to mechanically separate the laminate from the molded body during the crushing process in recycling.

[0016] In the above laminate, the porosity of the porous resin layer is preferably high (for example, 35% or more). For example, the porous resin layer can have such a high porosity by containing a predetermined amount of filler and being a porous resin stretched layer stretched in at least one direction. The high porosity of the porous resin layer suppresses the release of heat from the molded resin to the outside of the system, and this heat can be efficiently used to melt the polyethylene resin (A) in the uneven layer. Therefore, the adhesive strength between the laminate and the molded body can be improved.

[0017] As described above, the laminate according to this embodiment has an excellent balance of adhesive strength to the molded body while being easily mechanically separated from the molded body during the crushing process or the like during recycling. Furthermore, since the laminate according to this embodiment includes the concave-convex layer as described above, it is possible to suppress the occurrence of blisters during molding. Blisters can occur due to insufficient adhesive strength of the laminate to the molded body or air entrapment during molding, but the laminate according to this embodiment has a moderate adhesive strength as described above, and the concave-convex layer makes it easy to avoid air entrapment, so it is possible to effectively suppress the occurrence of blisters.

[0018] The laminate will be described in detail below with reference to FIGS. 1 and 2. FIGS. 1 and 2 are schematic cross-sectional views showing an example of the configuration of the laminate. As shown in FIG. 1, the laminate 10 includes a porous resin layer 200 and an uneven layer 100 provided on one main surface of the porous resin layer. When the laminate 10 is used to attach to a molded body, it is molded so that the side including the uneven layer 100 is the side to be attached to the molded body. As shown in FIG. 2, the molded body 10 may further include a second porous resin layer 300 laminated on the main surface of the porous resin layer 200 opposite the uneven layer 100. Furthermore, another layer, such as a substrate layer 400, may be further provided on the main surface of the second porous resin layer 300 opposite the porous resin layer 200.

[0019] (Uneven Layer) The laminate 10 including the uneven layer 100 can easily prevent the occurrence of blisters, such as lifting or swelling, during molding. This is thought to be due to the uneven shape of the uneven layer 100 easily forming an escape route for air when attached to a molded body. Here, the uneven layer may be formed into a desired pattern by coating or the like as long as it has an uneven shape as a laminate. Furthermore, as shown in FIG. 1, the uneven layer preferably has convex portions 100A (which may be formed by coating or the like) laminated on the porous resin layer 200, so that the surface of the porous resin layer 200 becomes concave portions 100B, and the concave portions 100A and the convex portions 100A form the uneven layer 100. (In other words, the uneven layer 100 in this embodiment is not limited to being formed as a layer having unevenness on its own, but also includes a form formed in combination with a portion of another layer to ultimately form an uneven shape.)

[0020] The uneven layer 100 contains a thermoplastic resin, and the thermoplastic resin of the uneven layer contains a polyethylene resin (A) having a melting point of 80 to 140°C.

[0021] The polyethylene resin (A) in the uneven layer 100 has a melting point of 80 to 140°C, which contributes to improved adhesion with the molded body while suppressing excessive adhesion, making it easier to mechanically separate from the molded body during the crushing process in recycling. Conventionally, laminates used for attachment to molded bodies have typically used low-melting-point thermoplastic resins on the entire heat-seal layer to improve heat-sealability and enhance adhesion to the molded body. However, the uneven layer 100 of this embodiment has an uneven shape, for example, patterned, on a portion of the surface of the laminate. Therefore, when used to attach to a molded body, the amount of resin melted by the heat of the molding resin is reduced. This appropriately reduces the adhesion between the molded body and the laminate, improving releasability during the crushing process in recycling. Furthermore, the melting point of the polyethylene resin (A) can be 90°C or higher, 100°C or higher, 110°C or higher, or 120°C or higher. In this case, since the polyethylene resin (A) has a relatively high melting point, it melts to a certain extent due to the heat of the molding resin, but does not melt as much as a thermoplastic resin with a lower melting point. Therefore, adhesion to the molded body due to melting is further reduced, and peelability during the crushing process in recycling can be improved. The melting point of the polyethylene resin (A) is preferably 122°C to 138°C, more preferably 125°C to 135°C, from the viewpoint of adhesion of the convex portions of the concave-convex layer to the molded body.

[0022] The polyethylene resin (A) is not particularly limited as long as it has a melting point within the above range, and examples thereof include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, metal salts of ethylene-methacrylic acid copolymer (ionomer), ethylene-acrylic acid alkyl ester copolymer, and ethylene-methacrylic acid alkyl ester copolymer (the alkyl group preferably has 1 to 8 carbon atoms). Two or more of these resins can also be mixed and used. From the viewpoints of melting behavior during molding and adhesion to the molding resin, the polyethylene resin (A) is preferably high-density polyethylene or medium-density polyethylene. In this specification, high-density polyethylene refers to a polyethylene having a density of 0.94 g / cm. ３ The above polyethylene resins, medium density polyethylene has a density of 0.93 g / cm ３ 0.94g / cm or more ３ Polyethylene resins with a density of less than 0.93 g / cm ３ This refers to polyethylene resins with a molecular weight of less than 1000.

[0023] The uneven layer 100 preferably further contains a polypropylene-based resin (B). In addition to the polyethylene-based resin (A), the inclusion of a polypropylene-based resin (B), which tends to have a higher melting point than the polyethylene-based resin (A), makes it easier to control the amount of melting of the uneven layer due to the heat of the molding resin. This makes it possible to adjust the adhesive strength so that the laminate can be easily mechanically separated from the molded body during the pulverization process in recycling. Examples of the polypropylene-based resin (B) include isotactic homopolypropylene and syndiotactic homopolypropylene, which are homopolymerized propylene, as well as polypropylene-based copolymers with various stereoregularities, primarily 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 polypropylene-based copolymer may be a binary system, a ternary system, or a multi-component system, and may be a random copolymer or a block copolymer. The polypropylene resin (B) preferably contains a propylene homopolymer, and more preferably is a propylene homopolymer, from the viewpoint of improving pore-forming properties and releasability during the pulverization step in recycling.

[0024] The thermoplastic resin of the concave-convex layer 100 may be the same as the thermoplastic resin of the porous resin layer 200 described later.

[0025] The content of the polyethylene resin (A) in the thermoplastic resin of the uneven layer described above is 40% by mass or more. The content of the polyethylene resin (A) in the above range improves the adhesive strength of the laminate with the molded article. From the viewpoint of adhesive strength, the content of the polyethylene resin (A) is preferably 42% by mass or more, more preferably 44% by mass or more, and even more preferably 46% by mass or more. When the uneven layer is formed by coating or the like, the content of the polyethylene resin (A) in the thermoplastic resin of the uneven layer may be 60% by mass or more, 80% by mass or more, or even 100% by mass. From the viewpoint of peelability, the content of the polyethylene resin (A) in the thermoplastic resin of the uneven layer is preferably 85% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, and particularly preferably 55% by mass or less. Furthermore, from the viewpoint of adhesiveness, the content of the polyethylene resin (A) in the uneven layer is preferably 10% by mass or more, and more preferably 20% by mass or more. From the same viewpoint, the content of the polyethylene resin (A) in the irregular layer may be 25% by mass or more.

[0026] In particular, when the uneven layer is formed in a desired pattern by coating or the like, the thermoplastic resin of the uneven layer preferably contains a polyethylene-based resin (A) having a melting point of 80°C or higher but less than 120°C. Furthermore, when the uneven layer is an uneven layer 100 formed integrally with the convex portions 100A, with the concave portions 100B on the surface of the porous resin layer 200, as shown in FIG. 1, the thermoplastic resin of the uneven layer preferably contains a polyethylene-based resin (A) having a melting point of 120 to 140°C. Furthermore, when the uneven layer is an uneven layer 100 formed integrally with the convex portions 100A, with the concave portions 100B on the surface of the porous resin layer 200, as described above, the thermoplastic resin of the uneven layer may further contain a resin having a melting point below 120°C in addition to the polyethylene-based resin (A) having a melting point of 120 to 140°C. In this case, the content of the resin having a melting point below 120°C is preferably 10% by mass or less in the thermoplastic resin of the uneven layer. By limiting the content of resins having a melting point below 120°C to 10% by mass or less, excessive adhesion to the molded body can be suppressed, and adhesive strength can be increased to a level that does not hinder separability during the crushing process during recycling.

[0027] (Filler) The irregularity layer may contain a filler. Examples of the filler include inorganic fillers and organic fillers, which may be used alone or in combination.

[0028] Examples of inorganic fillers include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, diatomaceous earth, titanium oxide, zinc oxide, barium sulfate, silicon oxide, magnesium oxide, and inorganic particles obtained by surface-treating these with a fatty acid, a polymer surfactant, an antistatic agent, etc. Among these, heavy calcium carbonate, light calcium carbonate, calcined clay, and talc are preferred because they have good pore formability and are inexpensive.

[0029] The organic filler is not particularly limited, but is preferably an organic particle that is incompatible with the polyolefin resin, has a melting point or glass transition temperature higher than that of the polyolefin resin, and is finely dispersed under the melt-kneading conditions of the polyolefin resin. Examples of organic fillers include organic particles of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyamide, polycarbonate, polyethylene sulfide, polyphenylene sulfide, polyimide, polyether ketone, polyether ether ketone, polymethyl methacrylate, poly-4-methyl-1-pentene, a homopolymer of a cyclic olefin, or a copolymer of a cyclic olefin and ethylene. The melting point (°C) and glass transition temperature (°C) of the resin can be measured by differential scanning calorimetry (DSC).

[0030] The inorganic filler and the organic filler may be selected from the above and used alone, or two or more may be used in combination. When two or more types are combined, a combination of an inorganic filler and an organic filler may be used. From the viewpoint of adhesiveness, the content of the filler in the uneven layer is preferably 70% by mass or less. From the same viewpoint, the content of the filler in the uneven layer may be 60% by mass or less, 40% by mass or less, 20% by mass, or 0% by mass.

[0031] The filler for the irregularity layer may be the same as the filler for the porous resin layer described below.

[0032] (Other Components) In the present invention, the uneven layer may optionally contain known additives as needed. Examples of additives include known auxiliaries such as antioxidants, light stabilizers, UV absorbers, crystal nucleating agents, plasticizers, filler dispersants, slip agents such as fatty acid amides, antiblocking agents, dyes, pigments, release agents, and flame retardants. In particular, when durability is required for the composite molded product, such as for outdoor use, it is preferable to include antioxidants, light stabilizers, etc. The content of the additives in the uneven layer may be appropriately selected within a range that does not impair the effects of the present invention, and may be, for example, 0.001 to 5% by mass.

[0033] For the uneven layer 100, the average height from the concave portion to the convex portion (difference in unevenness) is preferably 3 μm or more and 15 μm or less. When the average difference in unevenness is 3 μm or more, it becomes easier to obtain the effect of suppressing the occurrence of blisters due to air entrapment. When the average difference in unevenness is 15 μm or less, it becomes easier to suppress a decrease in the adhesion of the laminate to a molded product or a decrease in the printability of the laminate. From the same viewpoint, the average difference in unevenness is more preferably 5 μm or more, and even more preferably 6 μm or more. The average difference in unevenness is more preferably 13 μm or less, and even more preferably 10 μm or less.

[0034] The uneven layer 100 may be any layer that forms the above-described uneven shape on the surface of the laminate 10. The uneven shape may be provided on the porous resin layer 200 by coating, printing, or the like, or may be manufactured so as to have an uneven shape by integrally molding the uneven layer 100 with the porous resin layer 200. A manufacturing method for integrally molding the uneven layer 100 with the porous resin layer 200 includes, for example, a method in which the uneven layer 100 and the porous resin layer 200 are integrally molded on a film using the same thermoplastic resin composition, and then an uneven shape for forming the uneven layer is imparted to manufacture a laminate including the uneven layer 100 and the porous resin layer 200.

[0035] The uneven shape of the uneven layer 100 described above may be such that, when observed from a cross section in the thickness direction of the laminate, the uneven layer 100 has an uneven shape on the surface side (the side of the laminate when attached to the molded body), as shown in the example of the schematic cross-sectional view in FIG. 3(a). When observed from the front view from the main surface on the surface side of the uneven layer, this uneven shape may have a pattern observed based on convex or concave portions, as shown in the example of the schematic front view in FIG. 3(b). FIG. 3(b) shows an example in which a lattice-like pattern is formed. The pattern observed in the front view is not particularly limited. For example, this pattern may be any shape, such as a trapezoid, pyramidal, tortoiseshell, oblique line, or lattice.

[0036] (Area ratio of convex portions) The area ratio of the convex portions in the uneven layer is preferably 20% or more, more preferably 30% or more, and even more preferably 35% or more, from the viewpoint of improving adhesion and suppressing the occurrence of blisters. The area ratio of the convex portions is preferably 65% ​​or less, more preferably 55% or less, and even more preferably 45% or less, from the viewpoint of releasability and suppressing the occurrence of blisters. The "area ratio of convex portions" indicates the ratio of the area occupied by convex portions protruding from a reference plane obtained by taking a three-dimensional image of the surface of the uneven layer and analyzing the image, per unit area of ​​the surface of the uneven layer.

[0037] (Porosity of the uneven layer) The porosity of the uneven layer (particularly the convex portions) is preferably 30% or less. If the porosity of the uneven layer (of the convex portions) is 30% or less, when the laminate is attached to a molded body, the occupancy rate of the polyethylene resin (A) in the uneven layer increases, and the adhesive strength between the laminate and the molded body tends to increase. The porosity of the uneven layer may be 0%. Similarly, from the viewpoint of easily increasing adhesive strength, the porosity of the uneven portions is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less.

[0038] The porosity can be measured by determining the area ratio of pores in a certain region of the cross section of the uneven layer (particularly the convex portions) observed with an electron microscope. Specifically, an arbitrary portion of the uneven layer is cut out, embedded in epoxy resin, and solidified. Then, the uneven layer (laminate) is cut perpendicular to its surface using a microtome, and the cut surface is attached to an observation sample stage so that the observation surface is the observation surface. Gold, gold-palladium, or the like is vapor-deposited on the observation surface, and the pores are observed at an arbitrary magnification (e.g., 500x to 3000x) that is easy to observe with an electron microscope. The observed region is captured as image data. The obtained image data is processed using an image analyzer to determine the area ratio (%) of the pores, which can then be used as the porosity (%). In this case, the porosity can be determined by averaging the measured values ​​from observations of 10 or more arbitrary locations.

[0039] (Porous Resin Layer) The laminate 10 includes the porous resin layer 200, which facilitates improved adhesion to the molded body and facilitates peeling during the crushing process in recycling. As described above, when adhering to the molded body, the porous resin layer stores the thermal energy generated during molding, making it less likely to be released outside the system, and this facilitates sufficient use in the resin melting caused by the convex portions. Furthermore, the presence of the porous resin layer 200 also helps to prevent the occurrence of blisters. As described below, the porous resin layer preferably has a porosity greater than or equal to a predetermined level. This facilitates creating an escape route for air in the direction along the surface of the laminate (lateral direction) or dispersing and accommodating air, thereby preventing the formation of bulges between the laminate and the molded body. In addition, the presence of the porous resin layer 200 also reduces the occurrence of bulges due to the improved adhesive strength resulting from the heat insulating effect described above.

[0040] The porous resin layer 200 preferably contains a polyolefin-based resin as a thermoplastic resin. The polyolefin-based resin is not particularly limited, and examples include polyolefin-based resins such as polypropylene-based resin, high-density polyethylene, medium-density polyethylene, low-density polyethylene, poly-4-methyl-1-pentene, and ethylene-cyclic olefin copolymer. Two or more of these resins can also be mixed and used. Suitable examples of the polyolefin-based resin for the porous resin layer include those listed as the thermoplastic resin for the uneven layer. The melting point of the polyolefin-based resin for the porous resin layer is preferably 120°C or higher. The porous resin layer may contain a polyolefin-based resin with a melting point of less than 120°C, but the content of the polyolefin-based resin is preferably 10% by mass or less.

[0041] The porous resin layer 200 is preferably a porous stretched resin layer stretched at least uniaxially. Furthermore, the thermoplastic resin of the porous resin layer 200 preferably contains a crystalline polypropylene resin and a thermoplastic resin incompatible with the crystalline polypropylene resin. The crystalline polypropylene resin may be any of the polypropylene-based resins described above, with a crystallinity of 65% or more, preferably 66% or more, and particularly preferably 67-80%. When a crystallinity of 65% or more is used, phase separation between the crystalline polypropylene resin and the incompatible thermoplastic resin is likely to occur when an incompatible thermoplastic resin is used. Stretching in a phase-separated state facilitates the generation of pores originating from the interface, making it easier to achieve a higher porosity. This facilitates the achievement of higher adhesive strength and imparts brittleness to the porous resin layer, making the laminate more likely to peel from the molded body during the pulverization process in recycling. A crystallinity of 80% or less makes it easier to obtain. The degree of crystallinity can be calculated using the density of the crystalline polypropylene resin (the theoretically determined density of the crystalline and amorphous parts of the polypropylene resin) determined using a resin sample by a density gradient tube method, an underwater displacement method, or the like.

[0042] Examples of thermoplastic resins that are incompatible with crystalline polypropylene resins (hereinafter sometimes referred to as incompatible thermoplastic resins) include polyethylene-based resins, polystyrene-based resins, cyclic polyolefin-based resins, ethylene-cyclic olefin copolymer resins, polyamide-based resins such as nylon-6, nylon-6,6, nylon-6,10, and nylon-6,12, thermoplastic polyester-based resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, polybutylene terephthalate, polybutylene succinate, polylactic acid, and aliphatic polyesters, and polycarbonates. Two or more incompatible thermoplastic resins may be mixed and used. From the viewpoints of chemical resistance, production costs, and the like, polyethylene-based resins are preferred as incompatible thermoplastic resins.

[0043] From the viewpoint of pore formation, the thermoplastic resin preferably contains an appropriate amount of an incompatible thermoplastic resin in addition to crystalline polypropylene. The content of the incompatible thermoplastic resin in the thermoplastic resin is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and particularly preferably 45% by mass or more, from the viewpoints of improving the porosity, enhancing the heat insulating effect, and imparting brittleness to the porous resin layer. The content of the incompatible thermoplastic resin in the thermoplastic resin is preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, and particularly preferably 55% by mass or less, from the viewpoints of improving the porosity, enhancing the heat insulating effect, and imparting brittleness to the porous resin layer. Here, "incompatible" means that when a blend of a crystalline polypropylene resin and an incompatible thermoplastic resin is observed under an electron microscope, it has a sea-island morphology, and the dimensions of the sea-island structure are 0.3 to 10 μm.

[0044] The average particle size of the inorganic filler can be measured as the particle size corresponding to 50% of the total (cumulative 50% particle size) measured using a particle measuring device, for example, a laser diffraction particle measuring device (Microtrac, manufactured by Nikkiso Co., Ltd.) The average dispersed particle size of the organic filler can be determined by observing a cut surface of a sheet with an electron microscope, measuring the maximum diameters of at least 10 particles, and calculating the average value as the average dispersed particle size when dispersed in a resin by melt-kneading and dispersion.

[0045] The porous resin layer contains a filler to obtain a porous structure. The fillers for the porous resin layer can be those listed for the concave-convex layer above. When a layer containing a filler is stretched, a large number of fine pores centered on the filler can be formed in the layer, thereby obtaining a porous structure. The porous structure of the porous resin layer can be whitened, opaqued, and lightweight, and can also improve heat insulation and suppress the release of heat from the molding resin to the outside of the system. The filler is preferably surface-treated for hydrophobicity. When the filler is surface-treated for hydrophobicity, its dispersibility in the thermoplastic resin is improved, and a porous structure tends to be easily formed.

[0046] The average particle size of the inorganic filler and the average dispersed particle size of the organic filler are preferably large from the viewpoint of ease of mixing with the polyolefin resin. Furthermore, when voids are generated inside by stretching to improve opacity and printability, the average particle size of the inorganic filler and the average dispersed particle size of the organic filler are preferably small from the viewpoint of preventing problems such as sheet breakage and reduction in surface strength during stretching. Specifically, the average particle size of the inorganic filler and the average dispersed particle size of the organic filler are preferably 0.01 μm or more, more preferably 0.02 μm or more. Furthermore, the average particle size of the inorganic filler and the average dispersed particle size of the organic filler are preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less.

[0047] The content of the filler in the porous resin layer is 40% by mass or more. From the viewpoint of increasing the porosity and making the porous resin layer brittle, the content is preferably 45% by mass or more, more preferably 50% by mass or more, and even more preferably 52% by mass or more. The content of the filler in the porous resin layer is 70% by mass or less. From the viewpoint of imparting rigidity to the laminate and improving handleability, the content is preferably 65% ​​by mass or less, more preferably 60% by mass or less.

[0048] The porous resin layer may contain any known additives as needed, such as those listed for the concave-convex layer.

[0049] The thickness of the porous resin layer is preferably 2 μm or more, more preferably 4 μm or more, because the effects of whitening, opacity, weight reduction, and heat insulation are easily obtained. Moreover, the thickness of the porous resin layer is preferably 10 μm or less, more preferably 8 μm or less, because the mass of the laminate is easily reduced and handling is easily improved.

[0050] (Porosity) The porous resin layer preferably has a porous region with a porosity of 35 to 60%, which represents the proportion of pores. Such a high porosity of the porous resin layer can impart brittleness. This facilitates the progress of crushing (i.e., peeling from the laminated compact) from the brittle porous resin layer when a physical impact is applied to the labeled container during the crushing process in recycling, facilitating separation of the laminated compact. The porosity of the porous resin layer may be substantially uniform throughout the porous resin layer, but it does not necessarily have to be uniform throughout the layer. For example, as shown in FIG. 1 , the porosity of the porous resin layer 200 may be different between the region L where the convex portions of the uneven portion 100 are stacked and the region H where no convex portions are present. FIG. 1 shows, for example, a laminate in which the region H is a porous region with a high porosity, and the region L has a lower porosity than the porous region.

[0051] From the viewpoint of improving adhesive strength due to the heat insulating effect, the porosity of the porous region in the porous resin layer is preferably 37% or more, more preferably 40% or more, even more preferably 42% or more, and particularly preferably 45% or more. From the viewpoint of maintaining mechanical strength, the porosity of the porous region is preferably 70% or less, more preferably 65% ​​or less, even more preferably 60% or less, and particularly preferably 55% or less. The porosity of the porous resin layer can be measured by the same measuring method as the porosity of the above-mentioned uneven layer.

[0052] (Surface Treatment) From the viewpoint of improving adhesion to the molded body and other layers, it is also preferable that the porous resin layer is subjected to a surface treatment to activate the surface. Examples of the surface treatment include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment, etc., and these treatments can be combined. Among them, corona discharge treatment or flame treatment is preferred, and corona treatment is more preferred.

[0053] When corona discharge treatment is performed, the discharge amount is preferably 600 J / m ２ (10W・min / m ２ ) or more, more preferably 1,200 J / m２ (20W・min / m ２ ) or more. The discharge amount is preferably 12,000 J / m ２ (200W・min / m ２ ) or less, more preferably 10,800 J / m ２ (180W・min / m ２ The discharge amount when flame treatment is carried out is preferably 8,000 J / m ２ More preferably, 20,000 J / m or more. ２ The discharge amount is preferably 200,000 J / m or more. ２ or less, more preferably 100,000 J / m ２ The following is the result.

[0054] (Smoothness of Laminate) The smoothness of the surface of the uneven layer side of the laminate is preferably 10 to 150 seconds. The smoothness can be measured by the smoothness test method (Oken method) in JIS P 8155:2010. This smoothness is measured by measuring the flow rate of air flowing over the surface of a test piece under certain conditions, and the measurement result is calculated as the time (seconds) required for a unit flow rate of air to flow. Therefore, the longer the smoothness time (seconds), the higher the smoothness (smoother) of the measured surface tends to be.

[0055] If the smoothness of the surface of the concave-convex layer of the laminate is 150 seconds or less, a flow path for discharging ambient air is formed during molding, making it easier to suppress the occurrence of blisters and tending to improve releasability during the crushing process for recycling. If the smoothness is less than 10 seconds, the printability of the laminate is likely to deteriorate. The smoothness is preferably 100 seconds or less, more preferably 80 seconds or less, and even more preferably 60 seconds or less.

[0056] (Second porous resin layer) In addition to the porous resin layer and the concave-convex layer described above, the laminate preferably further comprises a second porous resin layer. The inclusion of the second porous resin layer further improves the heat insulating effect of the laminate, makes it easier to suppress the release of thermal energy outside the system during molding, and makes it easier to strengthen the adhesion to the molded body due to the convex portions.

[0057] The thermoplastic resins listed as examples of the porous resin layer can be used for the second porous resin layer. In the second porous resin layer, the thermoplastic resin is preferably a propylene-based resin, preferably a propylene homopolymer, from the viewpoints of pore formation and heat insulation. The second porous resin layer is preferably a porous stretched resin layer stretched at least uniaxially. The second porous resin layer also preferably contains a filler to achieve the desired porosity, and the fillers listed for the porous resin layer above can be used. However, from the viewpoint of ease of mixing with the polyolefin-based resin, the average particle diameter of the filler is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. Furthermore, when generating pores inside the sheet by stretching to improve opacity and printability, the average dispersed particle diameter of the filler is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less, from the viewpoint of preventing problems such as sheet tearing and reduced surface strength during stretching. The content of the filler in the second porous resin is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of achieving a high porosity as described below. From the viewpoint of imparting rigidity to the laminate and improving handleability, the content of the filler in the second porous resin layer is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less.

[0058] The thickness of the second porous resin layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of obtaining higher whitening, opacification, and heat insulation effects. Furthermore, the thickness of the second porous resin layer is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, from the viewpoint of reducing the mass of the laminate and improving handleability.

[0059] The second porous resin layer preferably has a porosity of 10 to 60%. From the viewpoint of improving adhesive strength due to the heat insulating effect, the porosity of the porous region in the second porous resin layer is preferably 15% or more, more preferably 20% or more, even more preferably 25% or more, and particularly preferably 30% or more. From the viewpoint of maintaining mechanical strength, the porosity of the second porous region is preferably 58% or less, more preferably 55% or less, even more preferably 52% or less, and particularly preferably 50% or less. The porosity of the second porous resin layer can be measured by the same method as that for the porosity of the concave-convex layer.

[0060] (Substrate Layer) The laminate may further include a substrate layer. The substrate layer can provide the laminate with an appropriate thickness and stiffness suitable for printing. There are no particular limitations on the material constituting the substrate layer; however, for example, the substrate layer is preferably a thermoplastic resin layer with excellent water resistance. Examples of the thermoplastic resin that can be used include resins similar to those listed as polyolefin-based resins for the porous resin layer. From the viewpoint of providing stiffness suitable for printing, the thermoplastic resin is preferably a polypropylene-based resin. The substrate layer may contain a filler, similar to the porous resin layer, and may be porous or a stretched layer stretched at least uniaxially. The substrate layer being a stretched layer makes it easier to provide stiffness to the laminate. The substrate layer may also contain other optional components.

[0061] When the substrate layer has a porous structure, the porosity is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more from the viewpoints of heat insulation, whitening, opacification, and weight reduction. From the viewpoint of maintaining mechanical strength, the porosity of the substrate layer is preferably 50% or less, more preferably 45% or less, and even more preferably 40% or less.

[0062] The thickness of the substrate layer is preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, from the viewpoint of easily obtaining sufficient stiffness. Also, from the viewpoint of easily improving handleability, the thickness of the substrate layer is preferably 400 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. The substrate layer may be a single layer or a sheet of two or more layers.

[0063] The laminate may have other layers such as a surface layer and a print-receiving layer in addition to the layers described above.

[0064] (Method for Producing Laminate) The laminate can be obtained, for example, by laminating sheet-like materials of a porous resin layer and a concave-convex layer formed on a film as described below, and then forming a pattern using an embossing roll to form a concave-convex shape. It is preferable to stretch the laminate in at least one direction after lamination. The method for forming the concave-convex shape of the concave-convex layer is not particularly limited, and methods such as forming by coating or printing on the porous resin layer, in addition to a method using an embossing roll, can be used. Examples of processing methods using an embossing roll include a method of forming an embossed pattern on the surface of a molded resin layer using a cooling roll, and a method of molding a resin layer, cooling the resin layer, and reheating the cooled resin layer to form an embossed pattern on the surface. Examples of embossed patterns provided on the embossing roll include trapezoidal, pyramidal, tortoiseshell, oblique, and lattice patterns. In the case of oblique and lattice patterns, the line density per 2.54 cm (1 inch) is preferably 20 lines or more, more preferably 30 lines or more, and even more preferably 50 lines or more, from the perspective of air evacuation. From the viewpoint of making it difficult for an embossed pattern to appear on the printed surface, the embossing depth is preferably 1,500 lines or less, more preferably 1,200 lines or less, and even more preferably 1,000 lines or less. From the viewpoint of efficiently discharging air from between the laminate and the molding resin during in-mold molding, the embossing depth is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. On the other hand, from the viewpoint of ensuring a sufficient contact area between the laminate and the molding resin, the embossing depth is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less.

[0065] When forming a concave-convex shape using an embossing roll, it is preferable that the embossing be performed after forming each layer and before the stretching and heat treatment steps. If a resin with a low melting point is applied to the heat-sealing layer and the heat-sealing surface is embossed, followed by the stretching and heat treatment steps, the concave-convex shape tends to be alleviated as the resin melts, and the smoothness tends to increase. However, in the laminate according to this embodiment, by using a resin with a relatively high melting point on the heat-sealing surface, the surface smoothness can be maintained low. Furthermore, by performing the stretching of the resin layer after embossing, the resin layer itself is stretched, but the stretching does not extend to the concave-convex layer (especially the convex portions). Therefore, many voids are formed in the stretched resin layer, while the formation of voids in the concave-convex layer (especially the convex portions) is not as great as in the resin layer.

[0066] Sheet-like materials such as porous resin layers can usually be obtained by mixing a polyolefin resin with other components to be contained in each layer and then molding the mixture. The molding method for each layer is not particularly limited, and various known molding methods can be used alone or in combination.

[0067] Each layer constituting the laminate can be molded into a film shape using, for example, cast molding in which a molten resin is extruded into a sheet shape using a single-layer or multi-layer T-die, I-die, etc. connected to a screw-type extruder, calendar molding, roll molding, inflation molding, etc. Each layer may also be molded by cast molding or calendar molding a mixture of a polyolefin resin and an organic solvent or oil, and then removing the solvent or oil.

[0068] Examples of molding methods for forming each layer into a multilayer structure include a multilayer die method using a feed block or a multi-manifold, and an extrusion lamination method using multiple dies, and these methods can also be combined.

[0069] Each layer may be unstretched or stretched. Examples of stretching methods include longitudinal stretching using the difference in peripheral speed between rolls, transverse stretching using a tenter oven, sequential biaxial stretching using a combination of these, rolling, simultaneous biaxial stretching using a tenter oven and a pantograph, and simultaneous biaxial stretching using a tenter oven and a linear motor. Also usable is simultaneous biaxial stretching (inflation molding) in which a molten resin is extruded into a tubular shape using a circular die connected to a screw extruder, and then air is blown into the extruded tubular shape.

[0070] When multiple layers are stretched, each layer may be stretched individually before lamination, or may be stretched together after lamination, or the stretched layers may be stretched again after lamination.

[0071] When the polyolefin resin used in each layer is an amorphous resin, the stretching temperature is preferably in the range of not less than the glass transition temperature of the polyolefin resin. When the polyolefin resin is a crystalline resin, the stretching temperature is preferably in the range of not less than the glass transition temperature of the amorphous part of the polyolefin resin and not more than the melting point of the crystalline part of the polyolefin resin, specifically, a temperature 2 to 60°C lower than the melting point of the polyolefin resin is preferred.

[0072] The stretching speed is not particularly limited, but is preferably within the range of 20 to 350 m / min from the viewpoint of stable stretching. The stretching ratio can also be appropriately determined taking into consideration the properties of the polyolefin resin used, etc. For example, when a layer containing a propylene homopolymer or a copolymer thereof is stretched in one direction, the stretching ratio usually has a lower limit of about 1.2 times, preferably 2 times, and an upper limit of 12 times, preferably 10 times. On the other hand, when biaxially stretching is performed, the stretching ratio, in terms of areal stretching ratio, is usually a lower limit of 1.5 times, preferably 10 times, and an upper limit of 60 times, preferably 50 times.

[0073] (Molded Product) The laminate of the present embodiment described above is suitable for use as a label attached to a molded product formed by direct blow molding or stretch blow molding using a preform. The material for forming the molded product is not particularly limited, and for example, a material containing a polyolefin resin can be used. The polyolefin resin contained in the molded product can be, for example, the same as that used in the porous resin layer. The polyolefin resin contained in the molded product and the polyolefin resin contained in the porous resin layer or the uneven layer may be the same or different. The color and shape of the molded product are not particularly limited, and any color or shape can be used.

[0074] 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. In the examples, "parts", "%", and the like are based on mass unless otherwise specified.

[0075] Example 1 Resin compositions for forming a substrate layer, a porous resin layer, and a second porous resin layer were prepared according to the following procedure, and then a laminate was obtained through a laminate preparation step.

[0076] (Preparation of resin composition a1) As a resin composition for forming a base layer, 80 mass % of a propylene homopolymer (trade name: Novatec PP FY4, manufactured by Japan Polypropylene Corporation) and 20 mass % of heavy calcium carbonate (trade name: Softon 1800, manufactured by Bihoku Funka Kogyo Co., Ltd.) as a filler were blended and stirred and mixed in a mixer to obtain resin composition a1.

[0077] (Preparation of resin composition b1) As a resin composition for forming a porous resin layer, a crystalline polypropylene resin (B) is a propylene homopolymer (trade name: Novatec PP FL4, manufactured by Japan Polypropylene Corporation, melting point 163 ° C, crystallinity 68%) 20% by mass, a polyethylene resin (A1) is an incompatible thermoplastic resin, a high-density polyethylene (trade name: Novatec HD HJ381, manufactured by Japan Polyethylene Corporation, melting point 131 ° C) 20% by mass, and a filler is a light calcium carbonate (trade name: Calfine YM30, manufactured by Maruo Calcium Co., Ltd.) 60% by mass was blended and stirred and mixed with a mixer to obtain a resin composition b1. In the resin composition b1, the content of the polyethylene resin (A1) in the thermoplastic resin is 50% by mass. In Example 1, the porous resin layer and the uneven layer were integrally formed into a sheet using the resin composition b1, and then the uneven layer was formed by applying an uneven shape in the preparation of the following laminate.

[0078] (Preparation of resin composition c1) As a resin composition for forming a second porous resin layer, 55% by mass of a propylene homopolymer (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation) and 45% by mass of a filler heavy calcium carbonate (trade name: Softon 1800, manufactured by Bihoku Funka Kogyo Co., Ltd.) were blended and stirred and mixed in a mixer to obtain a resin composition c1.

[0079] (Preparation of Laminate) Resin composition a1 (substrate layer) was melt-kneaded in an extruder set at 250° C., extruded into a sheet through a die, and cooled to 70° C. in a cooling device to obtain a single-layer unstretched sheet. This unstretched sheet was reheated to 145° C. and then stretched 5 times in the longitudinal direction by utilizing the difference in peripheral speed between multiple rolls to obtain a longitudinal uniaxially stretched film.

[0080] Resin composition b1 (irregular layer, porous resin layer) and resin composition c1 (second porous resin layer) were melt-kneaded in an extruder set at 250 ° C. individually, and then fed into an extrusion die. Then, the resin composition b1 and the resin composition c1 were extruded into a sheet so that the film derived from the resin composition b1 and the resin composition c1 was laminated, and laminated on one side of the longitudinal uniaxially stretched film (substrate layer), and #25 line, 25 μm deep gravure embossed between a metal cooling roll and a matte rubber roll, and the two were bonded by nipping and pressing while transferring the embossed pattern to the film side derived from the resin composition b1 (irregular layer, porous resin layer), and cooled with a cooling roll to obtain a sheet having an embossed convex irregular layer formed.

[0081] The sheet with the convex portions formed thereon was reheated to 158°C in an oven, then stretched 9 times in the transverse direction using a tenter stretching machine and heat-treated at 170°C to obtain the laminate of Example 1. The laminate of Example 1 had a total thickness of 86 μm. Each layer of the laminate, laminated in the order of base layer / second porous resin layer / porous resin layer (concave-convex layer), consisted of a1 / c1 / b1 resin composition, respectively, and had a biaxial / uniaxial / uniaxial stretching axis number. The thicknesses of the base layer / second porous resin layer / porous resin layer were 53 μm / 20 μm / 6 μm, and the porosities were 35% / 32% / 50%, respectively. Convex portions with a height of 7 μm were formed on the concave-convex layer of the laminate. The porosity of the concave-convex layer was 10%. The height of the convex portions of the uneven layer was measured by embedding the laminate in epoxy resin, solidifying it, and then using a microtome to prepare a cut surface parallel to the plane formed by the thickness direction and MD direction of the film.The cut surface was then metallized by vapor deposition, and then observed at 3000x magnification using an electron microscope (scanning microscope JCM-6000, manufactured by JEOL Ltd.) and measured by image measurement.

[0082] [Example 2] A laminate of Example 2 was obtained in the same manner as Example 1, except that the resin composition c1 forming the second porous resin layer was obtained by changing the content of propylene homopolymer to 70% by mass and heavy calcium carbonate to 30% by mass.

[0083] [Example 3] A laminate of Example 3 was obtained in the same manner as in Example 1, except that a resin composition b1 for forming a porous resin layer was obtained using 25 mass% of polypropylene resin (B), 25 mass% of polyethylene resin (A1), and 50 mass% of precipitated calcium carbonate. In the resin composition, the content of polyethylene resin (A1) in the thermoplastic resin was 50 mass%.

[0084] [Example 4] A laminate of Example 4 was obtained in the same manner as in Example 1, except that the resin composition c1 forming the second porous resin layer contained 40 mass% propylene homopolymer and 60 mass% heavy calcium carbonate.

[0085] [Example 5] (Preparation of Laminate) Resin composition a1 (substrate layer) was melt-kneaded in an extruder set at 250°C, extruded into a sheet through a die, and cooled to 70°C in a cooling device to obtain a single-layer unstretched sheet. This unstretched sheet was reheated to 145°C and then stretched 5 times in the longitudinal direction by utilizing the difference in peripheral speed between multiple rolls to obtain a longitudinal uniaxially stretched film.

[0086] Resin composition b1 (porous resin layer) and resin composition c1 (second porous resin layer) were melt-kneaded individually in an extruder set at 250 ° C., and then fed to an extrusion die. Next, films derived from resin composition b1 and resin composition c1 were extruded into a sheet so as to be laminated, and laminated on one side of the longitudinally uniaxially stretched film (substrate layer) to obtain a sheet.

[0087] The sheet was reheated to 158 ° C in an oven, then stretched 9 times in the transverse direction using a tenter stretcher and heat-treated at 170 ° C. A coating liquid consisting of a polyethylene resin (A2) ethylene methacrylic acid copolymer (trade name: AQUATEX AC-3100, manufactured by Japan Coating Resins Co., Ltd., melting point: 90 ° C.) was applied to the heat-treated sheet in a grid pattern so that the convex height after drying was 4 μm, and then dried to obtain the laminate of Example 5. The laminate of Example 5 had a total thickness of 83 μm. Of the laminate, the substrate layer / second porous resin layer / porous resin layer each had a resin composition of a1 / c1 / b1, respectively, and had a biaxial / uniaxial / uniaxial stretching axis number. The thicknesses of the substrate layer / second porous resin layer / porous resin layer were 53 μm / 20 μm / 6 μm, and the porosities were 35% / 32% / 50%, respectively. The concave-convex layer of the laminate had convex portions with a height of 4 μm. The porosity of the concave-convex layer was 0%.

[0088] [Example 6] A laminate of Example 6 was obtained in the same manner as in Example 1, except that a resin composition b1 for forming a porous resin layer was obtained using 30 mass% of polypropylene resin (B), 30 mass% of polyethylene resin (A1), and 40 mass% of precipitated calcium carbonate. In the resin composition, the content of polyethylene resin (A1) in the thermoplastic resin was 50 mass%.

[0089] [Example 7] A laminate of Example 7 was obtained in the same manner as in Example 1, except that the resin composition b1 for forming the porous resin layer was obtained using 8 mass% of the polypropylene resin (B), 32 mass% of the polyethylene resin (A1), and 60 mass% of precipitated calcium carbonate. In the resin composition, the content of the polyethylene resin (A1) in the thermoplastic resin was 80 mass%.

[0090] Comparative Example 1 A laminate of Comparative Example 1 was obtained in the same manner as in Example 1, except that the embossed pattern was not transferred in the production of the laminate.

[0091] [Comparative Example 2] A laminate of Comparative Example 2 was obtained in the same manner as in Example 1, except that the resin composition b1 for forming the porous resin layer contained 32 mass% of the polypropylene resin (B), 8 mass% of the polyethylene resin (A1), and 60 mass% of precipitated calcium carbonate. In the resin composition, the content of the polyethylene resin (A1) in the thermoplastic resin was 20 mass%.

[0092] [Comparative Example 3] A laminate of Comparative Example 3 was obtained in the same manner as in Example 1, except that the resin composition b1 was replaced with 100 mass% of metallocene-catalyzed polyethylene (product name: Engage 8401, manufactured by Dow Corporation, melting point 79°C).

[0093] [Comparative Example 4] A laminate of Comparative Example 4 was obtained in the same manner as in Example 1, except that the resin composition b1 for forming the porous resin layer contained 35 mass% of the polypropylene resin (B), 35 mass% of the polyethylene resin (A1), and 30 mass% of precipitated calcium carbonate. In the resin composition, the content of the polyethylene resin (A1) in the thermoplastic resin was 50 mass%.

[0094] The composite moldings of the above examples and comparative examples were evaluated as follows. The results are shown in Table 2.

[0095] (Porosity) After embedding the laminate in epoxy resin and solidifying it, a cut surface parallel to the plane formed by the thickness direction and MD direction of the film was prepared using a microtome. After metallizing this cut surface by vapor deposition, it was observed at 3000 times magnification using an electron microscope (JEOL Ltd., scanning microscope JCM-6000). The pore portions of each layer were binarized using image processing software (Inkscape), and the area ratio (%) of pores occupying the measurement range was calculated to determine the porosity (%) of each layer. The porosity of the porous resin layer was measured in the region without convexities in the convex layer, such as region H in FIG. 1.

[0096] (Thickness) The thickness (total thickness) of the laminate was measured in accordance with JIS K7130:1999 using a constant pressure thickness measuring instrument (product name: PG-01J, manufactured by Teclock Corporation). 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 with liquid nitrogen, and the sample was placed on a glass plate. A razor blade (product name: Proline Blade, manufactured by Schick Japan Co., Ltd.) was applied perpendicularly to the sample to cut it, preparing a sample for cross-sectional observation. The cross-section of the obtained sample was observed using a scanning electron microscope (product name: JCM-6000, manufactured by JEOL Ltd.), and the boundary lines for each thermoplastic resin composition of each layer were identified from the appearance. The total thickness of the laminate was calculated by multiplying the thickness ratio of each layer observed.

[0097] (Smoothness) The smoothness of the surface of the laminate was measured in accordance with JIS P 8155 using an Oken type smoothness tester (trade name: EYO-55-1M, manufactured by Asahi Seiko Co., Ltd.).

[0098] (Area ratio of convex portions %) The surface of the laminate (on the uneven layer side) was photographed using a laser microscope (trade name: VK-X 3000, manufactured by KEYENCE) in white light interference mode, and the three-dimensional image of a 1 mm x 1 mm area was analyzed using the VK-X 3000 multi-file analysis application to measure the area ratio of convex portions (ratio of the area of ​​convex portions to the total area of ​​the image). The area of ​​the convex portions was measured by defining a plane derived by the least squares method from the coordinates of the uneven layer surface obtained by analyzing the image as a reference plane, and the portions protruding from this reference plane were defined as convex portions. Images were taken of 10 locations on the laminate surface, and the average of the measured area ratios was taken as the area ratio % of convex portions on the surface of the uneven layer.

[0099] (Step of Attaching to Molded Article) In the following steps, the laminate of each Example or Comparative Example was attached to a large molded article, and the peelability and suppression of blister formation were evaluated.

[0100] The laminates of each Example or Comparative Example were punched into a rectangle measuring 120 mm wide and 150 mm long. The processed laminates were placed on one side of a blow molding die capable of molding a container-shaped molded article with a capacity of 3 L, with the porous resin layer (the uneven layer side) facing the cavity, and fixed onto the die using suction. Then, high-density polyethylene (Novatec HD HB420R, manufactured by Japan Polyethylene Co., Ltd.) was melted at 200°C between the dies and extruded into a parison shape. The parison at the part where the laminate was to be attached was set to 200°C. The die was then clamped, and a pressure of 4.2 kg / cm was applied. ２ Compressed air of 1000 psi was supplied into the parison. The parison was inflated for 16 seconds to adhere closely to the mold, forming a container and fusing it with the laminate. The molded body was cooled in the mold, and the mold was opened to obtain a molded body with the laminate attached (labeled molded body). The mold cooling temperature was 20°C, and the shot cycle time was 38 seconds per shot.

[0101] (Removability) A portion to which the laminate was attached was cut out from the labeled molded article of each Example and Comparative Example. The mass (Ta) of the cut-out labeled molded article was measured. The portion to which the laminate was attached was crushed into flakes using a crusher (manufactured by Morita Seiki, product name: XL-15, mesh screen size 8 mmφ) to prepare a sample for evaluation. Of the evaluation samples, the total mass (Tb) of the molded article and the laminate remaining on the molded article (not peeled off in the crushing process) was measured. Thereafter, the laminate was completely peeled off from the molded article, and the mass (B) of the remaining molded article was measured.

[0102] The peeling rate (%) of the laminate was calculated from the mass of the laminate before pulverization and the mass of the laminate peeled off in the pulverization process using the following formula: Peeling rate (%) of laminate = (Ta - Tb) / (Ta - B) x 100 The peeling rate calculated above was evaluated according to the following criteria: ◎: Peeling rate is 90% or more ○: Peeling rate is 85% or more but less than 90% ×: Peeling rate is less than 85%

[0103] (Blistering) The parison temperature was changed to 180°C, and the above-mentioned molded body attachment process was performed to produce labeled molded bodies. Below, labeled molded bodies with a parison temperature of 200°C, similar to the above-mentioned molded body attachment process, were also evaluated. The resulting labeled molded bodies were evaluated for blister suppression according to the following criteria. Here, blisters are likely to occur due to poor adhesion of the laminate to the molded body and insufficient air evacuation between the laminate and the molded body during molding. Therefore, by evaluating the presence or absence of blistering in this test, both the adhesion to the molded body and the air evacuation ability during attachment can be evaluated. Good: No blisters occurred in labeled molded bodies with parison temperatures of 180°C and 200°C. Fair: Blisters occurred in the labeled molded body with a parison temperature of 180°C, but not in the labeled molded body with a parison temperature of 200°C. Bad: Blisters occurred in both labeled laminated bodies with parison temperatures of 180°C and 200°C.

[0104]

[0105] When the laminates of Examples 1 to 7 were attached to a molded body, the peelability during the crushing process was 85% or more, and at least when the parison temperature was 200°C, no blisters occurred even when the laminates were attached to a large molded body, confirming good adhesion.

[0106] In Comparative Examples 1 and 2, blisters occurred in both labeled molded articles molded with parisons at 180°C and 200°C. In Comparative Example 1, blisters occurred due to air entrapment because a textured layer was not provided. Furthermore, in Comparative Example 2, the laminate did not adhere to the molded article at all, resulting in blisters. For this reason, it was not possible to evaluate releasability in Comparative Example 2. In Comparative Example 3, although strong adhesion to the molded article was possible, releasability during the crushing process was insufficient. In Comparative Example 4, the amount of filler in the porous resin layer was small, and releasability during the crushing process was insufficient.

[0107] 10 Laminate 100 Concave-convex layer 100A Convex portion 100B Concave portion 200 Porous resin layer 300 Second porous resin layer 400 Base layer H, L Regions

Claims

1. A laminate comprising a porous resin layer and a concave-convex layer provided on one of the main surfaces of the porous resin layer, wherein the porous resin layer contains a filler, the filler content of which is 40% by mass or more and 70% by mass or less, the concave-convex layer contains a thermoplastic resin, the thermoplastic resin of the concave-convex layer contains a polyethylene resin (A) having a melting point of 80 to 140°C, and the content of the polyethylene resin (A) in the thermoplastic resin is 40% by mass or more.

2. The laminate according to claim 1, wherein the smoothness of the surface on the uneven layer side is 10 to 150 seconds.

3. The laminate according to claim 1 or 2, wherein the porosity of the uneven layer is 30% or less.

4. The laminate according to claim 1 or 2, wherein the uneven layer further contains a polypropylene-based resin (B).

5. The laminate according to claim 1 or 2, further comprising a second porous resin layer, said second porous resin layer being laminated on the main surface of said porous resin layer opposite said uneven layer, and said second porous resin layer having a porosity of 25 to 60%.

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