Laminate

Abstract

To provide a laminate that satisfies both satisfactory adhesive strength to an adherend and physically satisfactory releasability.SOLUTION: A laminate comprises a heat seal layer and a ground layer, where the solid content of the heat seal layer per unit area is 0.05 to 1.5 g / m2, the heat seal layer includes thermoplastic resin (A) with the melting point of Tm(A), the ground layer includes thermoplastic resin (B), the thermoplastic resin (B) has a melting point Tm(B) of (Tm(A)+10°C) or higher and lower than (Tm(A)+60°C), the content of thermoplastic resin having a melting point lower than (Tm(A)+10°C) in the ground layer is 20 mass% or less, and the content of the thermoplastic resin (B) in the ground layer is 20 to 50 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate. [Background technology]

[0002] Generally, various contents are sold in plastic containers, and labels bearing information describing the contents are sometimes attached to the plastic containers.

[0003] Therefore, the label is usually required to have a strong adhesive strength to the resin container, but from the viewpoint of recycling the resin container, it is also required that the label be easily peelable from the labeled resin container after use.

[0004] In response to this, Patent Document 1 discloses an in-mold label that is both adhesive and releasable. The in-mold label can be peeled off from a resin container by immersing it in a high-temperature aqueous sodium hydroxide solution. This takes advantage of the process of immersing used resin containers in hot water or a hot alkaline aqueous solution to clean the container when recycling them. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-168354 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the timing for removing labels during the process of recycling resin containers is not limited to the step of immersing the containers in hot water or a hot alkaline aqueous solution for the above-mentioned cleaning. For example, labels may be removed by consumers themselves when sorting the containers, or labels may be removed during a crushing step of the resin containers carried out before the above-mentioned cleaning.

[0007] Therefore, an object of the present invention is to provide a laminate suitable for the above-mentioned label, which has both good adhesive strength to the adherend and good physical releasability. [Means for solving the problem]

[0008] There is a trade-off between having high adhesive strength to an adherend and being able to easily physically peel the laminate from the adherend without necessarily using a chemical solution. However, as a result of extensive research, the present inventors have found that in a laminate comprising a heat seal layer and a base layer, by specifying the thermoplastic resin contained in each layer and the solid content per unit area of ​​the heat seal layer, it is possible to achieve both high adhesive strength and good peelability, and have completed the present invention.

[0009] That is, the gist of one aspect of this embodiment is as follows. [1] A heat seal layer and a base layer are provided, The solid content per unit area of ​​the heat seal layer is 0.05 to 1.5 g / m 2 and the heat seal layer contains a thermoplastic resin (A) having a melting point Tm(A), the underlayer contains a thermoplastic resin (B), the thermoplastic resin (B) has a melting point Tm(B) of (Tm(A)+10°C) or more and less than (Tm(A)+60°C), the content of the thermoplastic resin having a melting point lower than (Tm(A)+10°C) in the underlayer is 20% by mass or less, The content of the thermoplastic resin (B) in the underlayer is 20 to 50% by mass. [2] The underlayer further contains a thermoplastic resin (C), The laminate according to [1] above, wherein the thermoplastic resin (C) has a melting point Tm(C) of (Tm(A)+60°C) or higher. [3] The laminate according to [1] or [2], wherein the underlayer further contains particles. [4] The laminate according to any one of the above [1] to [3], wherein the thickness of the underlayer is 0.5 to 10 μm. [5] The laminate according to any one of the above [1] to [4], wherein the content of the thermoplastic resin (A) in the heat seal layer is 50% by mass or more. [Effects of the Invention]

[0010] The laminate according to this embodiment can achieve both good adhesive strength to the adherend and good physical releasability. Therefore, the laminate adhered to the adherend with a strength high enough to cause no practical problems can be easily peeled off by a consumer or during a crushing process of the adherend, such as a resin container, and the like, and residual heat seal layer can be suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described in detail. However, the description below is one aspect of an embodiment of the present invention, and the present invention is not limited to these details. Furthermore, the present invention can be implemented with any modifications within the scope of the gist thereof. In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0012] <<Laminate>> The laminate according to this embodiment includes a heat seal layer and a base layer. The solid content per unit area of ​​the heat seal layer is 0.05 to 1.5 g / m 2 and the heat seal layer contains a thermoplastic resin (A). The underlayer contains 20 to 50 mass % of a thermoplastic resin (B) whose melting point Tm(B) is equal to or higher than (Tm(A)+10°C) and lower than (Tm(A)+60°C), where Tm(A) is the melting point of the thermoplastic resin (A) contained in the heat seal layer. The content of the thermoplastic resin in the underlayer, whose melting point is lower than (Tm(A)+10° C.) where Tm(A) is the melting point of the thermoplastic resin (A), is 20% by mass or less.

[0013] Generally, a heat seal layer needs to have a certain thickness in order to exhibit its heat sealing function. However, if the heat seal layer is thick, it tends to be difficult to peel by hand or during a crushing process. In contrast, in the laminate according to this embodiment, the solid content per unit area of ​​the heat seal layer is 0.05 to 1.5 g / m 2 By making the thickness as thin as 100 mm, high peelability can be achieved. On the other hand, by adopting the above-mentioned solid content per unit area, adhesiveness decreases. Therefore, the laminate according to this embodiment contains a specific thermoplastic resin (B) in the base layer that serves as the base for the heat seal layer. The thermoplastic resin (B) used has a melting point Tm(B) within a certain range relative to the melting point Tm(A) of the thermoplastic resin (A) contained in the heat seal layer, and its content is within a specific range. As a result, it has become possible to maintain an excellent balance between adhesion and releasability, which was previously thought to be difficult to achieve, and the present invention has been completed. Furthermore, with the laminate according to this embodiment, the heat seal layer is less likely to remain on the adherend when the laminate is peeled from the adherend, and the adherend can be recycled with higher purity after the laminate is peeled.

[0014] <Heat seal layer> The heat seal layer in this embodiment is a layer that, when heated, develops adhesiveness between the laminate and an adherend.

[0015] The heat seal layer in this embodiment contains a thermoplastic resin (A). The thermoplastic resin (A) is preferably a heat seal resin. Furthermore, from the viewpoint of adhesion to the adherend, the thermoplastic resin (A) preferably has a melting point, and more preferably has a melting point at which it melts at the heating temperature when adhering the laminate of this embodiment to the adherend.

[0016] The melting point Tm(A) of the thermoplastic resin (A) is preferably 60 to 120° C. From the viewpoint of adhesion to the adherend, the melting point Tm(A) is preferably 120° C. or lower, more preferably 110° C. or lower, and even more preferably 100° C. or lower. From the viewpoints of blocking prevention and releasability, the melting point Tm(A) is preferably 60° C. or higher, more preferably 80° C. or higher, and even more preferably 85° C. or higher.

[0017] The thermoplastic resin (A) may be, for example, a polyethylene resin. Examples of polyethylene resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid alkyl ester copolymer, and metal salts of ethylene-(meth)acrylic acid copolymer. Here, the carbon number of the alkyl group in the ethylene-(meth)acrylic acid alkyl ester copolymer is preferably 1 to 8. Furthermore, the metal salt of the ethylene-(meth)acrylic acid copolymer is preferably a salt with one or more metals selected from the group consisting of Zn, Al, Li, K, and Na. In this specification, (meth)acrylic acid means at least one of acrylic acid and methacrylic acid.

[0018] In this embodiment, the content of thermoplastic resin (A) in the heat seal layer is preferably 50% by mass or more, may be 50 to 100% by mass, or may be 50 to 99% by mass. From the viewpoint of enhancing adhesion to the adherend, the content is preferably 50% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 80% by mass or more. Furthermore, the content may be 100% by mass, i.e., the heat seal layer may consist solely of thermoplastic resin (A). However, if the heat seal layer contains other components, the content may be 99% by mass or less, 95% by mass or less, or 90% by mass or less, from the viewpoint of optimally obtaining the effects of the other components.

[0019] The heat seal layer in the present embodiment may further contain other components in addition to the thermoplastic resin (A). Examples of the other components include ethyleneimine polymers and auxiliary components.

[0020] In this embodiment, the heat seal layer preferably further contains an ethyleneimine-based polymer in addition to the thermoplastic resin (A). By including an ethyleneimine-based polymer in the heat seal layer, the adhesion between the heat seal layer and the underlayer can be improved, and the heat seal layer tends to be prevented from remaining on the adherend when the laminate is peeled from the adherend. Furthermore, by including an ethyleneimine-based polymer in the heat seal layer, good wettability with the underlayer can be imparted, and more stable adhesive strength can be achieved.

[0021] The content of the ethyleneimine polymer in the heat seal layer is preferably, for example, 1 to 15% by mass. From the viewpoint of wettability to the underlayer, the content is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. From the viewpoint of adhesion to the adherend, the content is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less.

[0022] Examples of auxiliary components in this embodiment include antistatic agents, crosslinking accelerators, antiblocking agents, pH adjusters, and antifoaming agents.

[0023] The content of each auxiliary component in the heat seal layer is, for example, 0.1 to 10% by mass, and may be 0.5 to 5% by mass. The total content of the auxiliary components is, for example, 0.1 to 10% by mass, and may be 0.5 to 5% by mass. From the viewpoint of optimally obtaining the effects of the auxiliary, each content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and the total content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. From the viewpoint of optimally obtaining the effects of the other components, each content is preferably 10% by mass or less, more preferably 5% by mass or less, and the total content is preferably 10% by mass or less, more preferably 5% by mass or less.

[0024] The heat seal layer in this embodiment may further contain a resin that does not have a melting point in addition to the thermoplastic resin (A). However, from the viewpoint of adhesive strength to the adherend, the content of the resin that does not have a melting point in the heat seal layer is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less.

[0025] From the viewpoint of forming a thin film, the heat seal layer in this embodiment is preferably a coating layer formed by coating.

[0026] The thickness of the heat seal layer in this embodiment can be determined by the amount of solid content (coating amount) per unit area. In this embodiment, the solid content per unit area of ​​the heat seal layer is 0.05 to 1.5 g / m 2 Here, from the viewpoint of adhesiveness to the adherend, the solid content is set to 0.05 g / m 2 or more, and 0.07 g / m 2 More than 0.08 g / m is preferable. 2 More preferably, 0.1 g / m or more 2 From the viewpoint of releasability, the solid content is more preferably 1.5 g / m. 2 less than or equal to 1.0 g / m 2 Less than 0.8 g / m is preferred 2 Less than 0.5 g / m is more preferable. 2The following is even more preferred:

[0027] In addition, conventional heat seal layers have had to be thicker than a certain thickness in order to exhibit good heat sealing properties. However, the laminate according to the present embodiment can ensure good adhesion to the adherend by using a specific thermoplastic resin (B) contained in the underlayer, so that the solid content per unit area of ​​the heat seal layer can be set within the above range, and as a result, good releasability can also be achieved.

[0028] <Base layer> The underlayer in this embodiment is a layer that underlies the heat seal layer in the laminate, and together with the heat seal layer, can precisely control the adhesiveness and peelability of the laminate to the adherend.

[0029] The underlayer may be a stretched layer or a non-stretched layer, and may be a single layer or a multilayer.

[0030] The underlayer in this embodiment contains a thermoplastic resin (B). The thermoplastic resin (B) preferably semi-melts at the heating temperature when the laminate is bonded to the adherend. When the underlayer contains such a thermoplastic resin (B) at a specific content, the elastic modulus of the underlayer is appropriately reduced at the heating temperature when heat-sealing is performed, thereby achieving high adhesion to the adherend and good releasability.

[0031] The thermoplastic resin (B) in this embodiment has a melting point Tm(B) higher than the melting point Tm(A) of the thermoplastic resin (A) contained in the heat seal layer. Specifically, the melting point Tm(B) of the thermoplastic resin (B) is preferably 10°C or higher and lower than the melting point Tm(A) of the thermoplastic resin (A). That is, the melting point Tm(B) is preferably (Tm(A)+10°C) or higher and lower than (Tm(A)+60°C). From the viewpoint of releasability, the difference between the melting point Tm(B) of the thermoplastic resin (B) and the melting point Tm(A) of the thermoplastic resin (A) is preferably 10° C. or more, more preferably 20° C. or more, and even more preferably 30° C. or more. From the viewpoint of adhesion to the adherend, the difference in melting point is preferably less than 60° C., more preferably 58° C. or less, and even more preferably 56° C. or less.

[0032] The melting point Tm(B) of the thermoplastic resin (B) in this embodiment is not particularly limited as long as it is within the above-mentioned range relative to the melting point Tm(A) of the thermoplastic resin (A), and will differ depending on the type of adherend, but is preferably, for example, 70° C. to 150° C. From the viewpoint of adhesion to the adherend, the melting point Tm(B) is preferably 150° C. or lower, more preferably 148° C. or lower, even more preferably 146° C. or lower, and even more preferably 145° C. or lower. On the other hand, from the viewpoint of releasability, the melting point Tm(B) is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, even more preferably 120°C or higher, and particularly preferably 130°C or higher.

[0033] Examples of the thermoplastic resin (B) include propylene-based copolymers having various stereoregularities, which are obtained by copolymerizing propylene as a main component with α-olefins such as ethylene, 1-butene, 1-hexene, 1-heptene, 1-octene, and 4-methyl-1-pentene, as well as ethylene-based polymers such as high-density polyethylene, medium-density polyethylene, and ethylene-α-olefin copolymers.

[0034] When the thermoplastic resin (B) is a propylene-based copolymer or an ethylene-based polymer as described above, the adhesion between the heat-sealing layer and the underlayer whose surface has been oxidized is enhanced, and as a result, when the laminate according to this embodiment is peeled from the adherend, the heat-sealing layer is less likely to remain on the adherend, and peeling marks of the laminate are less likely to remain.

[0035] In this embodiment, the content of the thermoplastic resin (B) in the underlayer is 20 to 50% by mass. From the viewpoint of improving adhesion to the adherend, the content is 20% by mass or more, preferably 25% by mass or more, and more preferably 30% by mass or more. Furthermore, from the viewpoint of suppressing a decrease in releasability due to excessive adhesion of the laminate to the adherend, the content is 50% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less.

[0036] The underlayer in the present embodiment may further contain other components in addition to the thermoplastic resin (B). Examples of the other components include the thermoplastic resin (C) and particles, antioxidants, light stabilizers, dispersants, and lubricants.

[0037] The thermoplastic resin (C) is a resin whose melting point Tm(C) is at least 60°C higher than the melting point Tm(A) of the thermoplastic resin (A), i.e., a thermoplastic resin that satisfies the relationship Tm(C)≧(Tm(A)+60°C).

[0038] In this embodiment, the undercoat layer preferably further contains the above-mentioned thermoplastic resin (C) in addition to the thermoplastic resin (B), from the viewpoint of preventing excessive adhesion to the adherend and making it easier to obtain good releasability.

[0039] The melting point Tm(C) of the thermoplastic resin (C) may be (Tm(A)+60°C) or higher, and is preferably, for example, (Tm(A)+60°C) or higher and (Tm(A)+100°C) or lower. From the viewpoint of peelability, the melting point Tm(C) is (Tm(A)+60°C) or higher, preferably (Tm(A)+65°C) or higher, and more preferably (Tm(A)+70°C) or higher. From the viewpoint of adhesive strength to the adherend, the melting point Tm(C) is preferably (Tm(A)+100°C) or lower, more preferably (Tm(A)+90°C) or lower, and even more preferably (Tm(A)+80°C) or lower.

[0040] The melting point Tm(C) of the thermoplastic resin (C) in this embodiment is not particularly limited as long as it is within the above-mentioned range relative to the melting point Tm(A) of the thermoplastic resin (A), and will vary depending on the type of adherend. However, for example, it is preferably 120°C or higher, more preferably 120 to 200°C. From the viewpoint of peelability, the melting point Tm(C) is preferably 120°C or higher, more preferably 145°C or higher, and even more preferably 155°C or higher. Furthermore, although there is no particular upper limit, from the viewpoint of adhesive strength to the adherend, the melting point Tm(C) is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower.

[0041] Examples of the thermoplastic resin (C) include polyolefin resins, polystyrene resins, polyester resins, polyamide resins, polycarbonate resins, etc. Among these, polyolefin resins are preferred, and propylene homopolymers are more preferred. When the laminate according to this embodiment further includes a substrate layer (described later), the thermoplastic resin (C) is preferably the same type of resin as the thermoplastic resin used in the substrate layer, from the viewpoint of interlaminar strength with the substrate layer. However, it is not required that the thermoplastic resin (C) and the thermoplastic resin used in the substrate layer be exactly the same resin. Furthermore, this does not exclude an embodiment in which the thermoplastic resin (C) and the thermoplastic resin used in the substrate layer are different types of resin.

[0042] When the underlayer of this embodiment contains a thermoplastic resin (C), the content of the thermoplastic resin (C) in the underlayer is preferably 5 to 80% by mass. From the viewpoint of releasability, the content is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 25% by mass or more. From the viewpoint of adhesion to the adherend, the content is preferably 80% by mass or less, more preferably 70% by mass or more, and even more preferably 60% by mass or less. The underlayer does not necessarily need to contain the thermoplastic resin (C).

[0043] In this embodiment, the underlayer preferably contains particles in addition to the thermoplastic resin (B) in order to prevent excessive adhesion to the adherend and to facilitate good releasability. When the underlayer is an oriented layer, it is more preferable that the underlayer contains particles. In this case, pores originating from the particles are formed in the underlayer.

[0044] The particles may be either inorganic particles or organic particles. Examples of inorganic particles include heavy calcium carbonate, light calcium carbonate, calcined clay, silica, diatomaceous earth, talc, titanium oxide, barium sulfate, and alumina. Examples of organic particles include polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-6,6, nylon-6, cyclic olefin, polystyrene, and polymethacrylate.

[0045] When the underlayer of this embodiment contains particles, the particle content in the underlayer is preferably 5 to 70% by mass. From the viewpoint of releasability, the content is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. From the viewpoint of adhesion to the adherend, the content is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. The underlayer does not necessarily need to contain particles.

[0046] One type of particle may be used, or two or more types may be used, and inorganic particles and organic particles may be used in combination. When two or more types of particles are contained, the total content thereof is preferably within the above range.

[0047] The underlayer in this embodiment preferably contains the thermoplastic resin (B) as well as the thermoplastic resin (C) and particles. In this case, the total content of the thermoplastic resin (C) and particles in the underlayer is preferably 40 to 80% by mass. From the viewpoint of releasability, the total content is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. From the viewpoint of adhesion of the laminate to an adherend, the total content is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0048] On the other hand, in the underlayer of this embodiment, the content of the thermoplastic resin having a melting point lower than (Tm(A)+10°C), where Tm(A) is the melting point of the thermoplastic resin (A), is 20% by mass or less. If the content of the thermoplastic resin having such a melting point in the underlayer is too high, the releasability of the laminate may be reduced. Therefore, the content of the thermoplastic resin in the underlayer is 20% by mass or less, preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6% by mass or less. The content of the thermoplastic resin may be 0% by mass. In other words, it is also preferable that the underlayer does not contain the thermoplastic resin.

[0049] In the present embodiment, the content of the thermoplastic resin (B) in the underlayer is preferably 50 to 100% by mass relative to the total of the thermoplastic resin (B) and the thermoplastic resin having a melting point lower than (Tm(A)+10°C), where Tm(A) is the melting point of the thermoplastic resin (A). From the viewpoint of preventing a decrease in the peelability of the laminate due to an increase in the content of the thermoplastic resin having such a melting point, the content is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 80% by mass or more, and even more preferably 95% by mass or more. The upper limit of the content is not particularly limited and may be 100% by mass. In other words, it is also preferable that the underlayer does not contain the thermoplastic resin.

[0050] The underlayer of this embodiment may further contain additives as other components, if necessary. Examples of additives include heat stabilizers, antioxidants, UV stabilizers, dispersants, and lubricants. Conventionally known additives can be used as the various additives. The content of the additive in the underlayer in this embodiment may be, for example, 0.1 to 10% by mass. Here, the content may be, for example, 0.1% by mass or more, 0.5% by mass or more, or 10% by mass or less, or 5% by mass or less. When two or more additives are contained, it is preferable that the total content thereof be within the above range.

[0051] In this embodiment, the underlayer preferably does not substantially contain a resin that does not have a melting point. Here, "substantially does not contain" means that the content in the underlayer is 10% by mass or less. The content of the resin that does not have a melting point in the underlayer may be 5% by mass or less, 1% by mass or less, or even 0% by mass. When the underlayer does not substantially contain a resin that does not have a melting point, the adhesion between the layers tends to be better maintained.

[0052] The thickness of the underlayer in this embodiment is preferably 0.5 to 10 μm. From the viewpoint of adhesion to the adherend, the thickness is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2.5 μm or more. From the viewpoint of releasability, the thickness is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3.5 μm or less.

[0053] In this embodiment, the porosity of the underlayer is preferably 30% or less. From the viewpoint of obtaining opacity and efficiently obtaining good adhesion to the adherend using the limited heat of the parison during in-mold molding, the porosity is preferably 0% or more, more preferably 3% or more, and even more preferably 5% or more. Furthermore, from the viewpoint of preventing the heat seal layer from remaining on the adherend, the porosity is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, and even more preferably 10% or less.

[0054] The porosity in this specification is a value calculated by the following formula (1). Porosity (%)={(ρ0-ρ) / ρ0}×100 ···(1) (In equation (1), ρ0 is the true density and ρ is the density.) Here, the true density of each layer is determined from a press sheet of the thermoplastic resin used by the underwater displacement method based on Method A of JIS K7112:1999 "Method for measuring density and specific gravity of plastics - non-foamed plastics." The density is determined by the following method. That is, based on JIS P8124:2011 "Paper and paperboard - Method of measurement of basis weight," a laminate is punched out to a size of 100 mm x 100 mm, weighed on an electronic balance, and the mass is divided by the area to determine the basis weight. The basis weight is then divided by the thickness of the laminate to determine the density.

[0055] <Base material layer> The laminate according to this embodiment may further include other layers in addition to the heat seal layer and the underlayer. Examples of other layers include a substrate layer. The substrate layer is a layer that supports the heat seal layer and the undercoat layer and provides the laminate with enough rigidity (stiffness) to allow handling during printing or processing. When the laminate according to this embodiment includes a base layer, the laminate preferably includes a heat seal layer, a base layer, and a base layer in this order.

[0056] The substrate layer in this embodiment may be a stretched layer or a non-stretched layer, and may be a single layer or multiple layers.

[0057] The substrate layer in this embodiment preferably contains a thermoplastic resin. The thermoplastic resin used in the substrate layer preferably does not melt or soften at the heating temperature when the laminate is adhered to the adherend.

[0058] The thermoplastic resin preferably has a melting point Tm that is 60°C or higher than the melting point Tm(A) of the thermoplastic resin (A). That is, the melting point Tm of the thermoplastic resin contained in the base layer is preferably (Tm(A) + 60°C) or higher, and more preferably (Tm(A) + 60°C) or higher and (Tm(A) + 120°C) or lower. Here, from the viewpoint of peelability, the melting point Tm is preferably (Tm(A) + 60°C) or higher. Furthermore, from the viewpoint of heat resistance, the melting point Tm is preferably (Tm(A) + 120°C) or lower, more preferably (Tm(A) + 110°C) or lower, and even more preferably (Tm(A) + 100°C) or lower.

[0059] The melting point Tm of the thermoplastic resin is not particularly limited as long as it is within the above-mentioned range relative to the melting point Tm(A) of the thermoplastic resin (A), but is preferably 120° C. or higher, more preferably 120 to 200° C. The melting point Tm is preferably 120° C. or higher, more preferably 145° C. or higher, and even more preferably 155° C. or higher. In addition, although there is no particular upper limit, from the viewpoint of moldability, the melting point Tm is preferably 200° C. or lower, more preferably 190° C. or lower, and even more preferably 180° C. or lower.

[0060] Examples of the thermoplastic resin used in this embodiment include polyolefin resins such as polyethylene resins and polypropylene resins, polystyrene resins, polyester resins, polyamide resins, polycarbonate resins, etc. The thermoplastic resins may be used alone or in combination of two or more.

[0061] The thermoplastic resin is preferably a polyolefin resin from the viewpoint of processability. In addition, when the underlayer contains a thermoplastic resin (C), the thermoplastic resin is preferably the same type of resin as the thermoplastic resin (C) from the viewpoint of interlaminar strength with the underlayer.

[0062] Examples of polyolefin resins include homopolymers composed of olefin monomers such as ethylene, propylene, butylene, pentene, hexene, octene, butadiene, isoprene, chloroprene, methyl-1-pentene, and cyclic olefins, and copolymers composed of two or more of the olefin monomers. The polyolefin resin is more preferably a polyethylene resin or a polypropylene resin.

[0063] In this embodiment, the content of the thermoplastic resin in the base layer is preferably 35 to 90% by mass. From the viewpoint of imparting rigidity, the content is preferably 35% by mass or more, and more preferably 40% by mass or more. From the viewpoint of obtaining the effects of other components, the content may be 90% by mass or less, or may be 70% by mass or less. When two or more thermoplastic resins are used in combination, the total content thereof is preferably within the above range.

[0064] The substrate layer in this embodiment may further contain other components, such as particles and additives.

[0065] In this embodiment, the substrate layer preferably further contains particles in addition to the thermoplastic resin. When the substrate layer is an oriented layer, particles are more preferably contained. This allows the substrate layer to have pores originating from the particles. As a result, the heat insulating properties of the laminate are increased, making it difficult for heat to escape from the parison, thereby improving the adhesive strength with the adherend. In addition, the whiteness and opacity can be increased to impart a paper texture to the laminate.

[0066] On the other hand, the base layer in this embodiment may not have pores or particles from the viewpoint of releasability, transparency, and the like.

[0067] In the case where the base layer in this embodiment contains particles, the particles may be either inorganic particles or organic particles. Examples of inorganic particles include heavy calcium carbonate, light calcium carbonate, calcined clay, silica, diatomaceous earth, talc, titanium oxide, barium sulfate, and alumina. Examples of organic particles include polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-6,6, nylon-6, cyclic olefin, polystyrene, and polymethacrylate.

[0068] In this embodiment, the particle content in the base layer is preferably 5 to 60% by mass. From the viewpoint of pore formation, the content 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 moldability, the content is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.

[0069] One type of particle may be used, or two or more types may be used, and inorganic particles and organic particles may be used in combination. When two or more types of particles are contained, the total content thereof is preferably within the above range.

[0070] The substrate layer in this embodiment may further contain additives as other components, if necessary. Examples of the additives include a heat stabilizer, an antioxidant, an ultraviolet stabilizer, a dispersant, a lubricant, etc. As the various additives, conventionally known ones can be used.

[0071] The content of the additive in the base layer in this embodiment may be, for example, 0.1 to 10% by mass. Here, the content may be, for example, 0.1% by mass or more, 0.5% by mass or more, or 10% by mass or less, or 5% by mass or less. When two or more types of additives are contained, it is preferable that the total content thereof be within the above range.

[0072] The thickness of the substrate layer in this embodiment may be, for example, 20 to 200 μm. From the viewpoints of imparting appropriate rigidity to the laminate to prevent wrinkles during printing or processing and facilitating fixing the laminate in the desired position when inserted into a mold during in-mold molding, the thickness may be, for example, 20 μm or more, preferably 30 μm or more, and more preferably 40 μm or more. Furthermore, from the viewpoint of preventing a decrease in strength at the interface between the laminate and the adherend (resin container) obtained by in-mold molding, the thickness may be 200 μm or less, preferably 150 μm or less, and more preferably 100 μm or less.

[0073] The porosity of the substrate layer in this embodiment is preferably 15 to 45%. From the viewpoint of obtaining opacity and, when the adherend is a resin container, obtaining efficient and good adhesion to the adherend by utilizing the heat of the parison during production of the resin container, the porosity is preferably 15% or more, more preferably 25% or more, and even more preferably 30% or more. Furthermore, from the viewpoint of mechanical strength, the porosity is preferably 45% or less, more preferably 40% or less, and even more preferably 38% or less.

[0074] <Adherend> The adherend to which the laminate according to this embodiment is adhered or peeled is not particularly limited as long as it is made of resin, and a preferred example is a resin container.

[0075] Examples of raw material resins for resin adherends include ethylene-based resins, propylene-based resins, ester-based resins, styrene-based resins, vinyl chloride-based resins, and other resins. Among these, ethylene-based resins and propylene-based resins are more preferred as the raw material resins.

[0076] <<Method for manufacturing laminate>> The method for producing the laminate according to this embodiment is not particularly limited as long as it can produce the laminate described in the above "Laminate". For example, it can be produced by providing a heat seal layer on an underlayer by coating or the like. Furthermore, when the laminate further includes a base layer, it can be produced by, for example, laminating the underlayer and the base layer in this order, and providing a heat seal layer on the surface of the underlayer opposite to the base layer by coating or the like.

[0077] For example, the following methods can be used, but are not limited to these. The resin composition for the base layer is melt-kneaded in advance, extruded into a sheet, and stretched in the longitudinal direction using the difference in peripheral speed between rolls to obtain a longitudinally stretched film. Next, the resin composition for the underlayer is melt-kneaded in advance, laminated into a sheet on the longitudinally stretched film obtained above, and stretched in the transverse direction at a specific temperature using a tenter. After heat treatment and cooling, a sheet comprising the base layer and underlayer is obtained.

[0078] The layers may be individually stretched before lamination, or may be stretched together after lamination, or the unstretched layer and the stretched layer may be stretched again after lamination.

[0079] Examples of the stretching method for stretching a film include a longitudinal stretching method utilizing the difference in peripheral speed between a group of rolls, a transverse stretching method utilizing a tenter oven, a sequential biaxial stretching method combining these, a rolling method, a simultaneous biaxial stretching method using a combination of a tenter oven and a pantograph, and a simultaneous biaxial stretching method using a combination of a tenter oven and a linear motor.

[0080] Alternatively, a simultaneous biaxial stretching (inflation molding) method can be used in which a molten resin is extruded into a tube shape using a circular die connected to a screw extruder, and then air is blown into the extruded material.

[0081] When the thermoplastic resin used is a non-crystalline resin, the stretching temperature is preferably equal to or higher than the glass transition point of the thermoplastic resin. When the thermoplastic resin is a crystalline resin, the stretching temperature is preferably equal to or higher than the glass transition point of the non-crystalline portion of the thermoplastic resin and equal to or lower than the melting point of the crystalline portion of the thermoplastic resin, and specifically, is preferably 2 to 60°C lower than the melting point of the thermoplastic resin.

[0082] The stretching speed is not particularly limited, but is preferably 20 to 350 m / min from the viewpoint of stable stretching.

[0083] The stretching ratio can be appropriately determined taking into consideration the properties of the thermoplastic resin used, etc. For example, when a resin film containing a propylene homopolymer or its copolymer is stretched in one direction, the lower limit of the stretching ratio is usually 1.2 times or more, preferably 2 times or more, and the upper limit is usually 12 times or less, preferably 10 times or less.

[0084] When the resin film is biaxially stretched, the stretching ratio, in terms of area stretching ratio, is usually 1.5 times or more, preferably 10 times or more, and the upper limit is usually 60 times or less, preferably 50 times or less.

[0085] A heat seal layer is formed on the sheet having the base layer and undercoat layer obtained above, and it is preferable to subject the surface of the sheet on the undercoat layer side to an oxidation treatment to activate the surface in order to improve adhesion with the heat seal layer.

[0086] Examples of the oxidation treatment include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and ozone treatment. The oxidation treatment is preferably a corona discharge treatment or a flame treatment, and more preferably a corona discharge treatment.

[0087] When performing corona discharge treatment, the discharge amount is, for example, 600 J / m 2 (10W min / m2 ) or more, 12,000J / m 2 (200W min / m 2 ) or less. Here, the discharge amount is preferably 600 J / m 2 (10W min / m 2 ) or more, and more preferably 1,200 J / m 2 (20W min / m 2 ) or more, and preferably 12,000 J / m 2 (200W min / m 2 ) or less, and more preferably 10,800 J / m 2 (180W min / m 2 ) is as follows.

[0088] The discharge amount when flame treatment is performed is, for example, 8,000 J / m 2 More than 200,000J / m 2 Here, the discharge amount is preferably 8,000 J / m or less. 2 or more, more preferably 20,000 J / m 2 or more, and preferably 200,000 J / m 2 or less, more preferably 100,000 J / m 2 The following is the result.

[0089] The heat seal layer can be provided on the undercoat layer of the sheet by coating or the like. Examples of coating methods include roll coating, blade coating, bar coating, air knife coating, gravure coating, reverse coating, die coating, lip coating, spray coating, comma coating, and size press coating.

[0090] "label" The laminate according to this embodiment is suitable for use in labels, for example. That is, the label according to this embodiment comprises a laminate and a printing layer. Here, the laminate may be one described above in the section "Laminate," and preferred embodiments are also the same, but it is more preferable that the label further comprises a base material layer.

[0091] The printed layer in this embodiment is a layer provided by printing on the substrate layer of the laminate on the side opposite to the undercoat layer side, thereby obtaining the label according to this embodiment.

[0092] Examples of the printed information on the printing layer include product names, product logos, manufacturer names, sales company names, usage instructions, bar codes, and the like.

[0093] Examples of printing methods for forming the print layer include gravure printing, offset printing, flexographic printing, seal printing, and screen printing.

[0094] <<Container with laminate, container with label>> The container with a laminate according to this embodiment includes a resin container and a laminate bonded to at least a partial area of ​​the surface of the resin container. Here, the laminate may be any of those described in the above section "Laminate," and preferred embodiments are also the same, but it is more preferred that the laminate further includes a base layer.

[0095] The labeled container according to this embodiment includes a resin container and a label attached to at least a portion of the surface of the resin container. The label may be any of those described above under "Labels," and preferred embodiments are also the same.

[0096] In the container with laminate and the container with label according to this embodiment, the laminate or the label is adhered to the surface of a resin container, respectively.

[0097] The resin container is preferably an in-mold molded product. Examples of the raw material resin for the resin container include ethylene-based resins, propylene-based resins, ester-based resins, styrene-based resins, vinyl chloride-based resins, and other resins. Among these, the raw material resin is preferably an ethylene-based resin or a propylene-based resin.

[0098] There are no particular limitations on the method for manufacturing the laminate-equipped container and labeled container according to this embodiment. In one embodiment of the production method, for example, the laminate or label is heated to activate the heat seal layer that constitutes the laminate or label, and then the laminate or label is attached to a resin container. Another embodiment is a method of manufacturing the laminate or label by placing a laminate or label at room temperature on the surface of a resin container, pressing the laminate or label whose heat seal layer has been activated by heating, and attaching the laminate or label to the resin container. In another preferred embodiment, a resin container is produced by in-mold molding, and a laminate or label having a heat-sealable layer activated by the heat of the molten molding resin during molding is attached to the surface of the resin container. In this case, the laminate or label becomes a laminate for in-mold molding or a label for in-mold molding. [Example]

[0099] The present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0100] "evaluation" <Melting point> The melting point of the thermoplastic resin was measured using a differential scanning calorimetry (DSC) in accordance with JIS K 7121 (2012). When there is one peak due to melting in the graph obtained by DSC, the melting peak temperature was taken as the melting point. When there are multiple peaks due to melting, the melting point was taken as the point where the integrated value of the peak areas from the low-temperature side of the multiple peaks is 50% of the total peak area.

[0101] <Thickness> The thickness of the entire laminate was measured in accordance with JIS K 7130 (1999) using a constant pressure thickness measuring instrument (manufactured by Teclock Corporation, trade name: PG-01J).

[0102] The thickness of each layer constituting the laminate was measured by the following method. The laminate was cooled to a temperature of -60°C or below with liquid nitrogen, placed on a glass plate, and then cut at a right angle with a razor blade (manufactured by Schick Japan Co., Ltd., product name: Proline Blade) to prepare a sample for cross-sectional observation. The resulting sample was then subjected to cross-sectional observation using a scanning electron microscope (manufactured by JEOL Ltd., product name: JSM-6490), and the boundaries of the heat seal layer, primer layer, and base layer were identified from the compositional appearance. The thickness ratio of each layer was then calculated, and the thickness of each layer was calculated by multiplying each thickness ratio by the total thickness of the laminate.

[0103] <Porosity> The porosity of the underlayer and the base layer constituting the laminate was calculated by the following formula (1). Porosity (%)={(ρ0-ρ) / ρ0}×100 ···(1) (In equation (1), ρ0 is the true density and ρ is the density.)

[0104] <Adhesiveness> The adhesiveness of the laminate was evaluated by the following method. The obtained laminate was cut into sheets and punched into rectangles with long sides of 8 cm and short sides of 6 cm. The punched laminate was placed on one side of a blow molding die capable of molding a resin container with a capacity of 0.4 L, with the heat seal layer facing the cavity side, and was fixed onto the die using suction. Between the molds, high-density polyethylene (product name: Novatec HD HB420R, manufactured by Japan Polyethylene Co., Ltd., MFR (JIS K 7210 (1999)): 0.2 g / 10 min, density (JIS K 7112 (1999)): 0.956 g / cm) was placed. 3 ) was melted at 180°C and extruded into a parison. The parison where the laminate was to be attached was set at 180°C. After the mold is clamped, 4.2 kg / cm 2 Compressed air was supplied into the parison for 20 seconds to expand the parison, causing it to adhere tightly to the mold, forming a container shape and fusing it with the laminate. The molded product was then cooled in the mold and opened to obtain a container with the laminate.

[0105] The container with the laminate obtained above was stored for two days in an environment of 23°C and 50% relative humidity. Next, the laminate and the container body in the area where the laminate was provided were cut out together with a cutter. Three measurement samples were then taken, each 12 cm long (8 cm for the adhesive-attached portion and 4 cm for the non-adhesive portion) and 1.5 cm wide (the adhesive was attached across the entire width), with the circumferential direction of the body of the container as the longitudinal direction. The same procedure was performed on two containers with the adhesive, and a total of six measurement samples were taken. Next, the adhesive portion of the laminate was carefully peeled off by hand from the non-adhesive portion, forming a gripping area by approximately 1 cm. A 1.5 cm wide PET film (50 μm thick) was placed on this gripping area and adhered with an adhesive to form a gripping area on the laminate side. This was used as a sample for measuring adhesive strength.

[0106] The adhesive strength measurement samples obtained above were subjected to a 180-degree peel test between the body of the resin container and the laminate in accordance with JIS K 6854-2 (1999) using a tensile testing machine (Shimadzu Corporation, model name: Autograph AGS-5kNJ) at a peel rate of 300 mm / min. The peel strength of the laminate was measured over a peel length of 25 to 75 mm, and the average value was taken as the peel strength of the sample. The above measurement was performed using six measurement samples for each laminate, and the average value of the peel strengths of the six samples was taken as the adhesive strength.

[0107] The results are shown in the "Adhesive strength (gf / 15mm)" column in Table 2. Adhesive strength of 150gf / 15mm or more was judged to be acceptable for practical use.

[0108] <Removability> The peelability of the laminate was evaluated by the following method. A container with the laminate was obtained in the same manner as described above in the section on <Adhesion>. The portion of the container with the laminate attached was cut out. The mass (Ta) of the cut-out container with the laminate attached was measured. This laminate-attached portion was crushed into flakes using a crusher (Morita Seiki, product name: XL-15, mesh screen size 8 mmφ) to prepare a sample for evaluation. Thereafter, the total mass (Tb) of the resin container and the laminate remaining on the resin container (not peeled off during the crushing process) was measured. Thereafter, the laminate was completely peeled off from the resin container, and the mass (B) of the remaining resin container was measured. Using the masses Ta, Tb and B measured above, the peeling rate (%) of the laminate was calculated according to the following formula. Peeling rate of laminate (%) = (Ta-Tb) / (Ta-B) × 100

[0109] The results are shown in the "Removability" column of Table 2, and the evaluation criteria are as follows. ○: Peeling rate is 95% or more, very good △: Peeling rate is between 70% and 95%, and practical ×: Peeling rate is less than 70%, defective

[0110] <Heat seal layer remaining after peeling> The remaining heat seal layer of the laminate was evaluated by the following method. After measuring the adhesive strength obtained in the above <Adhesion>, 20 points on the surface of the sample (resin container after peeling off the laminate) were observed using a scanning electron microscope (manufactured by JEOL Ltd., product name: JSM-6490) to confirm the presence or absence of a heat seal layer.

[0111] The results are shown in the column "Heat seal layer remaining" in Table 2, and the evaluation criteria are as follows. ○: Almost no heat seal layer remains on the observation surface, very good △: The heat seal layer remains slightly on the observation screen, and it is good. ×: The heat seal layer remains in more than half of the area of ​​the observation screen, and it is defective.

[0112] Example 1 <Base material layer> Propylene homopolymer (product name: Novatec PP FY4, manufactured by Japan Polypropylene Corporation, MFR (230 ° C, 2.16 kg load): 5 g / 10 min, melting point: 167 ° C) 70% by mass, high-density polyethylene (product name: Novatec HD HJ360, manufactured by Japan Polyethylene Corporation, MFR (190 ° C, 2.16 kg load): 5 g / 10 min, melting point: 131 ° C) 10% by mass, and heavy calcium carbonate fine powder (manufactured by Bihoku Funka Kogyo Co., Ltd., product name: Softon #1800, volume average particle size: 1.8 μm) 20% by mass were mixed and fed into an extrusion die set at 230 ° C and extruded into a sheet. This was cooled to 60 ° C using a cooling device to obtain an unstretched sheet. The obtained unstretched sheet was heated to 140°C and stretched 5 times in the machine direction by utilizing the difference in peripheral speed between the rolls to obtain a base layer as a stretched layer.

[0113] <Base layer> 30% by mass of an ethylene-propylene random copolymer (trade name: Wintec WFW4, manufactured by Japan Polypropylene Corporation; MFR (230°C, 2.16 kg load): 7 g / 10 min; melting point: 143°C), 25% by mass of a propylene homopolymer (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation; MFR (230°C, 2.16 kg load): 11 g / 10 min; melting point: 167°C), and 45% by mass of heavy calcium carbonate fine powder (trade name: Softon #1800, manufactured by Bihoku Funka Kogyo Co., Ltd.; volume average particle size: 1.8 μm) were mixed and melted in an extruder heated to 210°C. The mixture was then extruded into a sheet so as to be in contact with the base layer obtained above, and laminated on one side of the base layer to obtain a two-layer laminate sheet. The resulting two-layer laminate sheet was then cooled to 60°C, heated to approximately 150°C in a tenter oven and stretched 9 times in the transverse direction, and then further heated to 160°C for heat treatment. The film was then cooled to 60°C, and the edges were slit to obtain a laminated resin film consisting of a base layer and an undercoat layer with a total thickness of 83 μm (undercoat layer / base layer = 3 μm / 80 μm) and a number of stretching axes for each layer of undercoat layer / base layer = uniaxial / biaxial.

[0114] <Heat seal layer> The surface of the base layer side of the laminated resin film obtained above was subjected to a surface treatment by corona discharge. Then, a coating having a solid content per unit area of ​​0.15 g / m after drying was applied to the treated surface. 2 The coating composition was applied by a bar coater so as to obtain the following. The coating composition was a mixture of a dispersion of ethylene-methacrylic acid copolymer (EMAA) (product name: AC-3100, manufactured by Japan Coating Resins Co., Ltd., melting point: 90°C, average particle size: 1.0 μm) and polyethyleneimine (product name: Saftomer AC72, manufactured by Mitsubishi Chemical Corporation, solid content: 32% by mass), and the mixing amounts were adjusted so that the ethylene-methacrylic acid copolymer content in the resulting heat seal layer was 94% by mass and the polyethyleneimine content was 6% by mass. Next, the coating film was dried in an oven at 60°C to form a heat seal layer, thereby obtaining a laminate having a base layer, an underlayer, and a heat seal layer in this order. Table 1 shows the details of the components of the base layer, undercoat layer, and heat seal layer.

[0115] [Table 1]

[0116] Example 2 A laminate having a base layer, an underlayer, and a heat seal layer in this order was obtained in the same manner as in Example 1, except that during the manufacturing process of the base layer, the heating temperature of the unstretched sheet was changed from 140°C to 155°C and it was stretched in the vertical direction, and during the manufacturing process of the underlayer, the heating temperature of the two-layer laminate sheet was changed from approximately 150°C to approximately 170°C and it was stretched in the horizontal direction.

[0117] Examples 3 to 4, Examples 6 to 8, and Comparative Examples 1 to 3 A laminate comprising a base layer, a primer layer, and a heat seal layer in this order was obtained in the same manner as in Example 1, except that the mixing ratios of the ethylene-propylene random copolymer (trade name: Wintec WFW4, manufactured by Japan Polypropylene Corporation, MFR (230°C, 2.16 kg load): 7 g / 10 min, melting point: 143°C), propylene homopolymer (trade name: Novatec PP MA3, manufactured by Japan Polypropylene Corporation, MFR (230°C, 2.16 kg load): 11 g / 10 min, melting point: 167°C), and heavy calcium carbonate fine powder (trade name: Softon #1800, manufactured by Bihoku Funka Kogyo Co., Ltd., volume average particle diameter: 1.8 μm) in the primer layer were changed to the proportions shown in Table 2.

[0118] Example 5, Comparative Example 4 In forming the heat seal layer, the amount of coating composition applied was changed so that the solid content per unit area after drying would be the amount shown in Table 2. A laminate having a base layer, a primer layer, and a heat seal layer in this order was obtained in the same manner as in Example 1.

[0119] [Table 2]

[0120] From the results of Example 1, during in-mold molding to produce a resin container with a laminate, the heat-seal layer melts and the thermoplastic resin (B) contained in the base layer also melts or softens, resulting in stronger adhesion between the heat-seal layer and the base layer, and as a result, both high adhesive strength and good peelability were achieved. This is thought to be because the softening of the thermoplastic resin (B) makes it easier for the heat-seal layer to follow the shape of the adherend, increasing the contact area.

[0121] It is believed that in Example 2, the resin was more molten during stretching than in Example 1, which made it difficult for voids originating from the particles to form, resulting in a lower porosity. Because the insulating effect due to the porosity was reduced, the heat of the parison could not be used efficiently for bonding, and although the adhesive strength was slightly lower than in Example 1, good results were obtained.

[0122] In Comparative Example 1, the adhesive strength was reduced due to the increased content of thermoplastic resin (C) and particles, and the low content of thermoplastic resin (B) weakened the adhesion between the heat seal layer and the underlayer, which is thought to be why part of the heat seal layer remained on the adherend.

[0123] In Example 3, the content of thermoplastic resin (B) was high, so high adhesive strength was achieved, but when the resin container was crushed, part of the laminate did not peel off from the resin container.

[0124] In Comparative Example 2, although the heat seal layer was thin, the thermoplastic resin (B) in the base layer also contributed to the adhesion to the adherend, resulting in strong adhesive strength and the laminate hardly peeling off from the resin container when the resin container was crushed.

[0125] The results of Example 4 show that adhesive strength and peelability equivalent to those of Example 1 could be achieved even though the underlayer of the laminate did not contain particles.

[0126] In Comparative Example 3, the heat seal layer was thin and the underlayer did not contain the thermoplastic resin (B), resulting in a very low adhesive strength. Therefore, peelability was not evaluated, and this is also indicated as "-" in Table 2.

[0127] In Example 5, the adhesive strength was increased by increasing the solid content per unit area of ​​the heat seal layer. However, when the resin container was crushed, a part of the laminate did not peel off, and cohesive failure of the heat seal layer occurred, resulting in a part of the heat seal layer remaining on the peeled surface of the resin container.

[0128] In Comparative Example 4, the solid content per unit area of ​​the heat seal layer was increased compared to Example 5, and the laminate did not peel off when the resin container was crushed. In addition, the heat seal layer remained significantly on the peeled surface of the resin container.

[0129] Although Example 6 had a lower adhesive strength than Example 4, it still achieved an adhesive strength that was acceptable for practical use. In addition, the content of the thermoplastic resin (B) in the underlayer was low, and as a result, a part of the laminate did not peel off when the resin container was crushed. Furthermore, the results of Examples 7 and 8 showed the same tendency as the results of Examples 4 and 6.

[0130] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2024-056450) filed on March 29, 2024, the contents of which are incorporated herein by reference.

Claims

1. It has a heat seal layer and a base layer, The solid content per unit area of ​​the heat seal layer is 0.05 to 1.5 g / m ２ and the heat seal layer contains a thermoplastic resin (A) having a melting point Tm(A), the underlayer contains a thermoplastic resin (B), The thermoplastic resin (B) has a melting point Tm(B) of (Tm(A)+10°C) or more and less than (Tm(A)+60°C), the content of the thermoplastic resin having a melting point lower than (Tm(A)+10°C) in the underlayer is 20 mass% or less, The content of the thermoplastic resin (B) in the underlayer is 20 to 50 mass %.

2. the underlayer further contains a thermoplastic resin (C), The laminate according to claim 1, wherein the thermoplastic resin (C) has a melting point Tm(C) of (Tm(A)+60°C) or higher.

3. The laminate according to claim 1 or 2, wherein the underlayer further comprises particles.

4. 3. The laminate according to claim 1, wherein the thickness of the underlayer is 0.5 to 10 μm.

5. The laminate according to claim 1 or 2, wherein the content of the thermoplastic resin (A) in the heat seal layer is 50% by mass or more.

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