Laminate

Abstract

To provide a laminate that reduces the time and effort required to separate plastics from the laminate. [Solution] The laminate (10) comprises a vapor-deposited layer (2) having a first surface (2a) and a second surface (2b). The laminate (10) further comprises a hard plastic layer (1) located on the first surface (2a) side of the vapor-deposited layer (2) and a soft plastic layer (4) located on the second surface (2b) side of the vapor-deposited layer (2). The laminate (10) satisfies either requirement (1) or (2) below. (1) The plastic soft layer (4) has a strain property such that its shrinkage rate at 80°C is between 2% and 50%. (2) The vapor deposition layer (2) is further provided with a plastic strain layer (3) located on the first surface (2a) side and facing the vapor deposition layer (2) via the plastic hard layer (1).

Description

Technical Field

[0001] The present disclosure relates to a laminate.

Background Art

[0002] In recent years, against the background of environmental pollution caused by plastic products such as packages made of plastic films being discarded or dumped as garbage into the ocean, the development of technologies for recycling plastic films from plastic products has attracted attention.

[0003] For example, Patent Document 1 describes a method for producing a recycled substrate aimed at efficiently and simply obtaining a plastic substrate constituting a laminate as a recycled substrate from a printed matter or a laminated laminate. The method for producing a recycled substrate described in Patent Document 1 includes a step of immersing a laminate having a release layer (A) and an adhesive layer (C) between a plastic substrate 1 and a plastic substrate 2 in a basic aqueous solution. In the method for producing a recycled substrate described in Patent Document 1, the release layer (A) is a vapor deposition layer made of aluminum oxide and / or silica, or a layer containing aluminum and a binder resin, and the adhesive layer (C) is a layer formed by an ether-based urethane adhesive and / or an ester-based urethane adhesive. The basic aqueous solution contains a basic compound at 0.5 to 10% by mass of the entire basic aqueous solution, and the water temperature of the basic aqueous solution during immersion is 30 to 120°C.

[0004] Furthermore, Patent Document 2 describes a packaging material and a method for manufacturing a recycled substrate that has excellent adhesion to the substrate necessary for packaging materials, allows removal of not only the printed layer on the outside of the package but also the printed layer on the inside, has excellent delamination properties for both types of substrates constituting the packaging material, and is suitable for plastic recycling. The packaging material described in Patent Document 2 comprises a first substrate, a first delamination layer for delaminating the first substrate and separating, recovering, and recycling the first substrate, a second substrate, and a second delamination layer for delaminating the second substrate and separating, recovering, and recycling the second substrate. The first delamination layer is formed from a first delamination layer forming composition (A), and the second delamination layer is formed from a second delamination layer forming composition (B). The first desorption layer forming composition (A) comprises a resin (a) and a solvent, wherein the acid value of the resin (a) is 15 mg KOH / g or more, and the second desorption layer forming composition (B) comprises at least one inorganic substance selected from the group consisting of aluminum, aluminum oxide, and silica, and the inorganic substance is 10% by weight or more of the total amount of the second desorption layer forming composition (B). Furthermore, the method for manufacturing a recycled substrate described in Patent Document 2 includes a step of immersing the above packaging material in a basic aqueous solution, wherein the basic aqueous solution contains a basic compound in an amount of 0.5 to 10% by mass of the total basic aqueous solution, and the temperature of the basic aqueous solution during immersion is 30 to 120°C. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-175620 [Patent Document 2] Japanese Patent Publication No. 2021-098295 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the inventions described in Reference Documents 1 and 2, it was necessary to prepare a specific type of adhesive or a resin with a specific acid value in order to separate the plastic from the laminate or packaging. Therefore, conventionally, there was a problem that separating the plastic from the laminate or packaging was time-consuming and laborious. [Means for solving the problem]

[0007] The laminate of the present disclosure is a laminate comprising a vapor-deposited layer, wherein the vapor-deposited layer comprises a first surface and a second surface opposite to the first surface, and the laminate further comprises a hard plastic layer located on the first surface side of the vapor-deposited layer and having a storage modulus of 1000 MPa or more and 5000 MPa or less at 80°C, and a soft plastic layer located on the second surface side of the vapor-deposited layer and having a storage modulus of 30 MPa or more and 700 MPa or less at 80°C. The following requirements must be met: (1) or (2). (1) The plastic soft layer has a deformation property such that its shrinkage rate at 80°C is between 2% and 50%. (2) The device further comprises a plastic strain layer located on the first surface side of the vapor-deposited layer and facing the vapor-deposited layer via the hard plastic layer, having a shrinkage rate of 2% or more and 50% or less at 80°C. [Effects of the Invention]

[0008] The laminates of this disclosure provide laminates that can reduce the time and effort required to separate plastics from the laminate. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of an example of the laminate according to Embodiment 1. [Figure 2] This is a schematic cross-sectional view illustrating the presumed mechanism of action and effect of the laminate of Embodiment 1. [Figure 3] This is a schematic cross-sectional view illustrating the presumed mechanism of action and effect of the laminate of Embodiment 1. [Figure 4]This is a schematic cross-sectional view of an example of the laminate according to Embodiment 2. [Figure 5] This is a schematic cross-sectional view of an example of the laminate according to Embodiment 3. [Figure 6] This is a schematic cross-sectional view of an example of the laminate according to Embodiment 4. [Figure 7] This is a schematic cross-sectional view of an example of the laminate according to Embodiment 5. [Modes for carrying out the invention]

[0010] The embodiments will be described below. In the drawings used to describe the embodiments, the same reference numerals represent the same part or a corresponding part.

[0011] [Embodiment 1] Figure 1 shows a schematic cross-sectional view of an example of a laminate according to Embodiment 1. The laminate 10 shown in Figure 1 comprises a vapor-deposited layer 2. The vapor-deposited layer 2 comprises a first surface 2a and a second surface 2b opposite to the first surface 2a. The laminate 10 comprises a hard plastic layer 1 located on the first surface 2a side of the vapor-deposited layer 2, with a storage modulus of 1000 MPa or more and 5000 MPa or less at 80°C, and a soft plastic layer 4 located on the second surface 2b side of the vapor-deposited layer 2, with a storage modulus of 30 MPa or more and 700 MPa or less at 80°C. The laminate 10 also has a strained plastic layer 3 located on the first surface 2a side of the vapor-deposited layer 2, facing the vapor-deposited layer 2 via the hard plastic layer 1, with a shrinkage rate of 2% or more and 50% or less at 80°C.

[0012] In the laminate 10 of Embodiment 1, the hard plastic layer 1 may be in contact with the vapor-deposited layer 2, and adhesives (not shown) for bonding these layers may be located between all layers except the one between the hard plastic layer 1 and the vapor-deposited layer 2. Furthermore, the laminate 10 of Embodiment 1 may include other plastic layers, such as a second hard plastic layer or a printed layer, between the hard plastic layer 1 and the strained plastic layer 3. The description of the second hard plastic layer is the same as the description of the hard plastic layer 1 below.

[0013] <Plastic hardening layer> The hard plastic layer 1 is a plastic layer having a storage modulus at 80°C of 1000 MPa or more and 5000 MPa or less. As the hard plastic layer 1, for example, a layer made of biaxially oriented polyethylene terephthalate resin (hereinafter sometimes referred to as "biaxially oriented PET") film can be used. If the storage modulus of the hard plastic layer 1 at 80°C differs between the MD (Machine Direction) direction and the TD (Transverse Direction) direction, the smaller of the storage modulus of the hard plastic layer 1 at 80°C in the MD direction and the storage modulus of the hard plastic layer 1 at 80°C in the TD direction shall be taken as the storage modulus of the hard plastic layer 1 at 80°C. The storage modulus of the hard plastic layer 1 at 80°C in the MD direction is measured as follows. First, a sample is prepared by cutting the hard plastic resin film used to form the hard plastic layer 1 to a width (short side) of 10 mm × length (long side) of 50 mm, with the TD direction being the short side direction and the MD direction being the long side direction. Next, the sample is attached to the chuck of the following apparatus in an atmosphere of 25°C. Then, with the sample attached to the chuck of the apparatus, the atmosphere is heated from 25°C to 150°C. The storage modulus of the plastic hard layer 1 at 80°C in the MD direction is measured by drawing a viscoelastic-temperature curve from 25°C to 150°C using the dynamic viscoelastic method and reading the storage modulus at 80°C. The storage modulus of the plastic hard layer 1 at 80°C in the TD direction is measured in the same manner as the storage modulus of the plastic hard layer 1 at 80°C in the MD direction, except that a sample is prepared by cutting the hard plastic resin film to a width (short side) of 10 mm and a length (long side) of 50 mm, with the MD direction being the short side direction and the TD direction being the long side direction. The thickness of the plastic hard layer 1 can be, for example, 4 μm to 25 μm.

[0014] In Embodiment 1, the conditions used for measuring the storage modulus at 80°C are as follows. Equipment: DMS6100 (manufactured by SII Nanotechnology Co., Ltd.) Measurement mode: Tensile mode Distance between chucks: 10 mm Frequency: Sine wave 1 Hz Strain amplitude: 10 μm Minimum tension: 50 mN Tension gain: 1.5 Initial value of force amplitude: 50 mN Temperature range: 25°C to 150°C Heating rate: 2°C / min Measurement atmosphere: Air Measurement thickness: Thickness of hard plastic resin film

[0015] <Plastic soft layer> The plastic flexible layer 4 is a plastic layer having a storage modulus at 80°C of 30 MPa or more and 700 MPa or less. If the storage modulus of the plastic flexible layer 4 at 80°C differs between the MD direction and the TD direction, the larger of the storage modulus of the plastic flexible layer 4 at 80°C in the MD direction and the storage modulus of the plastic flexible layer 4 at 80°C in the TD direction shall be used as the storage modulus of the plastic flexible layer 4 at 80°C. As the plastic flexible layer 4, for example, a layer made of polybutylene terephthalate resin (hereinafter sometimes referred to as "PBT") film, polyolefin resin (hereinafter sometimes referred to as "PO") film, polyethylene terephthalate resin (hereinafter sometimes referred to as "PET") film, nylon film, etc., can be used. More specifically, as the plastic flexible layer 4, examples include unoriented PET film, unoriented PBT film, unoriented PO film, uniaxially oriented PET film, uniaxially oriented PBT film, uniaxially oriented PO film, biaxially oriented PBT film, biaxially oriented PO film, and biaxially oriented nylon film. The storage modulus of the flexible plastic layer 4 at 80°C is measured by the same method and under the same conditions as the storage modulus of the rigid plastic layer 1 at 80°C, except that a flexible plastic resin film is used for forming the flexible plastic layer 4 instead of the rigid plastic resin film used for forming the rigid plastic layer 1. The flexible plastic layer 4 may be a sealant layer. If the flexible plastic layer 4 is a sealant layer, the laminate 10 can be formed into a packaging body such as a pouch by heat-sealing the flexible plastic layers 4 together. If the flexible plastic layer 4 is a sealant layer, it is preferable to use a PO film as the flexible plastic layer 4, and it is particularly preferable to use linear low-density polyethylene resin (hereinafter sometimes referred to as "LLDPE"). When the flexible plastic layer 4 is a sealant layer, the laminate 10 can be made particularly recyclable because the sealant layer, which is thicker than the other layers, is easily separated by the plastic separation mechanism described later. The thickness of the flexible plastic layer 4 can be, for example, 50 μm or more and 200 μm or less.

[0016] Although the plastic strain layer 3, described later, may have the characteristics of a plastic flexible layer, if the plastic flexible layer 4 is a sealant layer, it is preferable that the plastic flexible layer 4 does not have the characteristics of a plastic strain layer (shrinkage rate of 2% or more and 50% or less at 80°C) from the viewpoint of dimensional stability and seal adhesion due to heat sealing.

[0017] <Plastic strained layer> The plastic strain layer 3 is a plastic layer having a shrinkage rate of 2% or more and 50% or less at 80°C. If the shrinkage rate of the plastic strain layer 3 at 80°C differs between the MD direction and the TD direction, the larger of the shrinkage rate of the plastic strain layer 3 at 80°C in the MD direction and the shrinkage rate of the plastic strain layer 3 at 80°C in the TD direction shall be used as the shrinkage rate of the plastic strain layer 3 at 80°C. From the viewpoint of more efficiently reducing the time required to separate the plastic from the laminate 10 and from the viewpoint of ensuring the quality stability of the laminate 10, it is more preferable that the shrinkage rate of the plastic strain layer 3 at 80°C be 2% or more and 10%, and even more preferable that it be 3% or more and 6% or less. As the plastic strain layer 3, for example, a layer made of unoriented PET film, unoriented polybutylene terephthalate resin film, unoriented polyolefin resin film, uniaxially oriented polyethylene terephthalate resin (hereinafter sometimes referred to as "uniaxially oriented PET") film, uniaxially oriented polybutylene terephthalate resin film, or uniaxially oriented polyolefin resin film can be used. The shrinkage rate of the plastic strain layer 3 at 80°C is measured as follows. First, a sample is prepared by cutting the strained plastic resin film used to form the plastic strain layer 3 so that the MD direction × TD direction is 50 mm × 50 mm. Next, the sample is immersed in a hot water bath at 80°C for 10 seconds. Next, the TD direction length of the sample before immersion in the hot water bath and the TD direction length after immersion in the hot water bath are used to calculate the shrinkage rate of the plastic strain layer 3 at 80°C in the MD direction in the same way as the TD direction. The shrinkage rate of the plastic strain layer 3 at 80°C is defined as the larger of the shrinkage rate of the plastic strain layer 3 at 80°C in the MD direction and the shrinkage rate of the plastic strain layer 3 at 80°C in the TD direction. The thickness of the plastic strain layer 3 can be, for example, 10 μm or more and 80 μm or less.

[0018] Shrinkage rate of plastic strain layer 3 at 80°C [%] = 100 × [{(TD direction length of the sample before immersion in an 80°C hot water bath) - (TD direction length of the sample after immersion in an 80°C hot water bath)} / (TD direction length of the sample before immersion in an 80°C hot water bath)] ... (Equation A)

[0019] The storage modulus of the plastic strain layer 3 at 80°C is preferably 30 MPa to 700 MPa. In this case, the time required to separate the plastic from the laminate 10 can be reduced more efficiently. The storage modulus of the plastic strain layer 3 at 80°C can be measured using the same method and under the same conditions as the storage modulus of the plastic hard layer 1 at 80°C, except that a strained plastic resin film used for forming the plastic strain layer 3 is used instead of the hard plastic resin film used for forming the plastic hard layer 1. When the storage modulus of the plastic strain layer 3 at 80°C is 30 MPa to 700 MPa, the plastic strain layer 3 can have the characteristics of the plastic soft layer 4. In this case, plastic separation, as described later, becomes possible without the need to separately provide the plastic soft layer 4.

[0020] The shortest distance d between the plastic strain layer 3 and the plastic soft layer 4 (the shortest distance d between the surface of the plastic strain layer 3 on the vapor-deposited layer 2 side and the surface of the plastic soft layer 4 on the vapor-deposited layer 2 side) is preferably 30 μm or less. When this shortest distance d is 30 μm or less, the time required to separate the plastic from the laminate 10 can be reduced more efficiently.

[0021] <Vapour-deposited layer> The vapor-deposited layer 2 has gas barrier properties and is a layer that can dissolve in the separation liquid when the laminate 10 is immersed in the separation liquid described later. For example, a vapor-deposited layer of aluminum or silica can be used as the vapor-deposited layer 2.

[0022] <Method for manufacturing laminates> The laminate 10 shown in Figure 1 can be manufactured, for example, as follows. First, a hard plastic raw material roll is prepared, on which a hard plastic resin film constituting the hard plastic layer 1 is wound; a strained plastic raw material roll is prepared, on which a strained plastic resin film constituting the strained plastic layer 3 is wound; and a flexible plastic raw material roll is prepared, on which a flexible plastic resin film constituting the flexible plastic layer 4 is wound. Next, while pulling out the hard plastic resin film from the hard plastic raw material roll, inorganic particles such as aluminum used to form the vapor deposition layer 2 are vapor-deposited onto one surface of the hard plastic resin film, and then the film is wound into a roll again to produce a vapor-deposited hard plastic raw material roll comprising the hard plastic layer 1 and the vapor-deposited layer 2 formed on one surface of the hard plastic layer 1.

[0023] Next, while pulling out the hard plastic resin film after the deposition of inorganic particles from the vapor-deposited hard plastic raw material roll, adhesive is applied to the second surface 2b of the vapor-deposited layer 2 opposite to the hard plastic layer 1. Then, the soft plastic resin film pulled out from the soft plastic raw material roll is attached to the second surface 2b of the vapor-deposited layer 2 to which the adhesive has been applied. Next, adhesive is applied to the surface of the hard plastic layer 1 opposite to the second surface 2b of the vapor-deposited layer 2. Then, the strained plastic resin film pulled out from the strained plastic raw material roll is attached to the surface of the hard plastic layer 1 opposite to the second surface 2b of the vapor-deposited layer 2 to which the adhesive has been applied, and the roll is wound up again. By doing so, the laminate 10 of Embodiment 1 can be manufactured.

[0024] <Mechanism of plastic separation> The presumed mechanism of plastic separation in the laminate 10 of Embodiment 1 will be described below with reference to the schematic cross-sectional views in Figures 2 and 3. The plastic soft layer 4 can be separated from the laminate 10 by immersing the laminate 10 in the separation liquid and dissolving the vapor-deposited layer 2. As the separation liquid, for example, a basic aqueous solution or an acidic aqueous solution with a temperature of 80°C or higher can be used. As a basic aqueous solution, for example, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution can be used. As an acidic aqueous solution, for example, a hydrochloric acid aqueous solution, a sulfuric acid aqueous solution, or a nitric acid aqueous solution can be used.

[0025] Looking at it in more detail, for example as shown in Figure 2, in the initial stage when the laminate 10 is immersed in the separation liquid, the separation liquid comes into contact with the vapor-deposited layer 2 located at the edge of the laminate 10 and dissolves the vapor-deposited layer 2 located at the edge of the laminate 10 in the direction of arrow 5. Then, the plastic strained layer 3 is heated by the separation liquid and contracts in the direction of arrow 6 (towards the inside of the laminate 10). As a result, as the dissolution of the vapor-deposited layer 2 by the separation liquid progresses toward the inside of the laminate 10, as shown in Figure 3, the plastic strained layer 3 is pulled toward the inside and upward of the laminate 10, indicated by arrow 7, along with the plastic hard layer 1, while the plastic soft layer 4 floats and flutters in the separation liquid without following the direction in which the plastic hard layer 1 is pulled. In other words, in this case, each layer adjacent to the vapor-deposited layer 2 (in this embodiment, the plastic hard layer 1 and the plastic soft layer 4) can be made so as not to interfere with the contact between the vapor-deposited layer 2 and the separation liquid. As a result, the distance between the hard plastic layer 1 and the soft plastic layer 4 at the edges of the laminate 10 increases, and as the dissolution of the vapor-deposited layer 2 by the separation liquid progresses, the rate of dissolution of the vapor-deposited layer 2 by the separation liquid can be accelerated.

[0026] As described above, in the laminate 10 of Embodiment 1, it is not necessary to prepare a specific type of adhesive and a resin with a specific acid value, as in the conventional method, in order to separate the plastic from the laminate 10. Furthermore, as the dissolution of the vapor-deposited layer 2 by the separation liquid progresses due to the shrinkage of the plastic strain layer 3 caused by heating the separation liquid, the dissolution rate of the vapor-deposited layer 2 by the separation liquid can be accelerated. Therefore, in the laminate 10 of Embodiment 1, it is possible to reduce the time and effort required to separate the plastic from the laminate 10.

[0027] [Embodiment 2] The laminate 10 of Embodiment 2 is characterized in that the laminate 10 does not have a plastic strain layer 3, and the plastic flexible layer 4 has a strain property in which the shrinkage rate at 80°C is 2% or more and 50% or less. The shrinkage rate of the plastic flexible layer 4 at 80°C can be measured by the same method and under the same conditions as the shrinkage rate of the plastic strain layer 3 at 80°C, except that a flexible plastic resin film used for forming the plastic flexible layer 4 is used instead of a strain plastic resin film used for forming the plastic strain layer 3.

[0028] Figure 4 shows a schematic cross-sectional view of an example of the laminate 10 of Embodiment 2. The laminate 10 of Embodiment 2 shown in Figure 4 comprises a hard plastic layer 1 on the first surface 2a side of the vapor-deposited layer 2 and a soft plastic layer 4 on the second surface 2b side of the vapor-deposited layer 2, but does not have a plastic strain layer 3. In the laminate 10 of Embodiment 2, the storage modulus of the hard plastic layer 1 at 80°C is 1000 MPa or more and 5000 MPa or less, and the storage modulus of the soft plastic layer 4 at 80°C is 30 MPa or more and 700 MPa or less. In the laminate 10 of Embodiment 2, it is not necessary to prepare a specific type of adhesive and a resin with a specific acid value in order to separate the plastic from the laminate 10. Furthermore, in the laminate 10 of Embodiment 2, the plastic soft plastic layer 4 having the above-mentioned strain properties is heated and shrinks by the separation liquid, which can accelerate the dissolution rate of the vapor-deposited layer 2 as the dissolution of the vapor-deposited layer 2 progresses. Therefore, in the laminate 10 of Embodiment 2, it is possible to reduce the time and effort required to separate the plastic from the laminate 10.

[0029] Furthermore, since the description of Embodiment 2 other than that described above is the same as that of Embodiment 1, that description will not be repeated.

[0030] [Embodiment 3] Figure 5 shows a schematic cross-sectional view of an example of the laminate 10 of Embodiment 3. The laminate 10 of Embodiment 3 shown in Figure 5 is characterized by having a plastic protective layer 9 on the surface of the plastic strain layer 3 opposite to the plastic hard layer 1 side. Because the laminate 10 of Embodiment 3 further includes a plastic protective layer 9, the usability of the laminate 10 can be improved compared to the laminate 10 of Embodiment 1. For example, if the plastic protective layer 9 is a layer with high puncture strength made of polyamide synthetic resin (nylon resin, hereinafter sometimes referred to as "Ny") and the plastic flexible layer 4 is a sealant layer, the laminate 10 of Embodiment 3 is suitable as a film for pouches with high puncture strength. The description of Embodiment 3 other than that is the same as that of Embodiment 1, so that description will not be repeated.

[0031] [Embodiment 4] Figure 6 shows a schematic cross-sectional view of an example of the laminate 10 of Embodiment 4. The laminate 10 of Embodiment 4 shown in Figure 6 is characterized by having a plastic protective layer 9 between the plastic hard layer 1 and the plastic strain layer 3. The description of Embodiment 4 other than that is the same as that of Embodiments 1 and 3, so that description will not be repeated.

[0032] [Embodiment 5] Figure 7 shows a schematic cross-sectional view of an example of the laminate 10 of Embodiment 5. The laminate 10 of Embodiment 4 shown in Figure 7 is characterized by having a recycled material-containing plastic flexible layer 11 between the plastic flexible layer 4 and the vapor-deposited layer 2. As the recycled material-containing plastic flexible layer 11, for example, a plastic flexible layer formed using recycled plastic, etc., that constitutes the plastic flexible layer 4 separated and recovered from the laminate 10 of Embodiments 1 to 5, or a plastic flexible layer formed by recycling the recovered plastic flexible layer 4 (for example, LLDPE) and mixing it with a new flexible plastic resin (for example, LLDPE) can be used.

[0033] The position of the recycled material-containing plastic soft layer 11 is not limited to this, and in the configuration of the laminate 10 of Embodiment 4 shown in Figure 7, the positions of the plastic soft layer 4 and the recycled material-containing plastic soft layer 11 may be swapped. When the plastic soft layer located on the second surface 2b side of the vapor-deposited layer 2 is a sealant layer, it is preferable that the vapor-deposited layer 2, the recycled material-containing plastic soft layer 11, and the plastic soft layer 4 are laminated in that order, as shown in Figure 7, in order to suitably exhibit sealant performance. In addition, in the laminate 10 of Embodiment 5, the recycled material-containing plastic soft layer 11 may be placed instead of the plastic soft layer 4. In this case, the laminate 10 of Embodiment 5 is superior in terms of environmental friendliness. [Examples]

[0034] [Fabrication of laminates] Laminates for Examples 1-6 and Comparative Examples 1-7 were fabricated as described below. In the fabrication of the laminates for Examples 1-6 and Comparative Examples 1-7, the following materials were used as the hard plastic layer, flexible plastic layer, strained plastic layer, and protective plastic layer. In the following, among the flexible plastic layers, a flexible plastic layer having strain properties with a shrinkage rate of 2% or more and 50% or less at 80°C will be referred to as the "flexible (strained) plastic layer," and a flexible plastic layer without strain properties with a shrinkage rate of 2% or more and 50% or less at 80°C will be referred to as the "non-strained (flexible) plastic layer."

[0035] (a) Plastic hard layer A 12 μm thick biaxially oriented PET film with a storage modulus of 1000 MPa to 5000 MPa at 80°C.

[0036] (b) Plastic flexible (strained) layer A uniaxially oriented PET film with a thickness of 45 μm and an unoriented PET film with a thickness of 60 μm, having a storage modulus of 30 MPa to 700 MPa at 80°C and a shrinkage rate of 2% to 50% at 80°C.

[0037] (c) Plastic flexible (non-strained) layer LLDPE films with a thickness of 150 μm, 50 μm, and 140 μm, which have a storage modulus of 30 MPa to 700 MPa at 80°C, but do not exhibit strain due to a shrinkage rate of 2% to 50% at 80°C.

[0038] (d) Plastic strain layer A uniaxially oriented PET film with a thickness of 50 μm and an unoriented PET film with a thickness of 60 μm, both exhibiting strain properties with a shrinkage rate of 2% to 50% at 80°C.

[0039] (e) Plastic protective layer Ny film with a thickness of 15 μm.

[0040] The storage modulus at 80°C for the rigid and flexible plastic layers, as well as the shrinkage rates at 80°C for the flexible and strained plastic layers in the laminates of Examples 1-6 and Comparative Examples 1-7, were measured using the method described above. In addition, in the preparation of the laminates of Examples 1-6 and Comparative Examples 1-7, the biaxially oriented PET film, unoriented PET film, LLDPE film, and Ny film used had the same properties (storage modulus at 80°C and shrinkage rate at 80°C).

[0041] <Example 1> As the laminate 10 of Example 1, a laminate 10 having the schematic cross-section shown in Figure 4 was fabricated. The laminate 10 of Example 1 was fabricated by forming a vapor-deposited layer 2 by vapor-depositing aluminum onto one surface of a 12 μm thick biaxially oriented PET film as the hard plastic layer 1, and then attaching a 45 μm thick uniaxially oriented PET (shrink PET) film as the soft (strained) plastic layer 4 to the second surface 2b of the vapor-deposited layer 2 with an adhesive.

[0042] <Example 2> The laminate of Example 2 was prepared using the same method as in Example 1, except that a 60 μm thick unoriented PET film was used as the plastic flexible (strained) layer 4 instead of a 45 μm thick uniaxially oriented PET film.

[0043] <Example 3> As the laminate 10 of Example 3, a laminate 10 having the schematic cross-section shown in Figure 1 was fabricated. The laminate 10 of Example 3 was fabricated as follows. First, a vapor-deposited layer 2 was formed by vapor-depositing aluminum onto one surface of a 12 μm thick biaxially oriented PET film, which served as the hard plastic layer 1. Next, a 50 μm thick uniaxially oriented PET (longitudinal PET) film, which served as the strained plastic layer 3, was attached to the surface of the hard plastic layer 1 with an adhesive, and a 150 μm thick LLDPE film, which served as the flexible (unstrained) plastic layer 4, was attached to the second surface 2b of the vapor-deposited layer 2 with an adhesive, thereby fabricating the laminate 10 of Example 3. Note that "longitudinal PET" refers to a film that has shrinkage properties in the MD direction of the film roll.

[0044] <Example 4> The laminate 10 of Example 4 was fabricated using the same method as in Example 3, except that a 60 μm thick unoriented PET film was used as the plastic strain layer 3 instead of a 50 μm thick uniaxially oriented PET (longitudinal PET) film, and a 15 μm thick Ny film was attached to the plastic strain layer 3 as a plastic protective layer 9 with adhesive to create a laminate 10 having the schematic cross-section shown in Figure 5.

[0045] <Example 5> The laminate 10 of Example 5 was fabricated using the same method as in Example 4, except that a 15 μm thick Ny film as a plastic protective layer 9 was attached with adhesive to the surface of the hard plastic layer 1 opposite to the vapor-deposited layer 2, and a 60 μm thick unstretched PET film as a plastic strain layer 3 was attached with adhesive to the surface of the Ny film, thereby creating a laminate 10 having the schematic cross-section shown in Figure 6.

[0046] <Example 6> The laminate 10 of Example 6 was fabricated in the same manner as in Example 5, except that a 12 μm thick biaxially oriented PET film was used as the second hard plastic layer, instead of a 15 μm thick Ny film as the plastic protective layer 9, and the laminate 10 was fabricated by attaching a 12 μm thick biaxially oriented PET film to the surfaces of the hard plastic layer 1 and the strained plastic layer 3 with an adhesive.

[0047] <Comparative Example 1> A laminate 10 of Comparative Example 1 was prepared using the same method as in Example 1, except that a biaxially oriented PET film with a thickness of 12 μm was attached to the second surface 2b of the vapor-deposited layer 2 with an adhesive, instead of a uniaxially oriented PET film with a thickness of 45 μm as the plastic flexible (strained) layer 4.

[0048] <Comparative Example 2> A laminate 10 of Comparative Example 2 was prepared using the same method as in Example 2, except that a vapor-deposited layer 2 was formed on one surface of a 50 μm thick LLDPE film, which served as the flexible (unstrained) plastic layer, instead of a 12 μm thick biaxially oriented PET film serving as the rigid plastic layer 1.

[0049] <Comparative Example 3> The laminate 10 of Comparative Example 3 was prepared using the same method as in Comparative Example 2, except that a 12 μm thick biaxially oriented PET film was attached to the second surface 2b of the vapor-deposited layer 2 with an adhesive, instead of a 60 μm thick unoriented PET film as the plastic flexible (strained) layer 4.

[0050] <Comparative Example 4> The laminate 10 of Comparative Example 4 was prepared using the same method as in Comparative Example 3, except that a 60 μm thick unoriented PET film as a plastic flexible (strained) layer and a 15 μm thick Ny film as a plastic protective layer 9 were attached in this order from the side of the vapor-deposited layer 2 between a 12 μm thick biaxially oriented PET film as a plastic rigid layer and a vapor-deposited layer 2.

[0051] <Comparative Example 5> The laminate 10 of Comparative Example 5 was manufactured by forming a vapor-deposited layer 2 by vapor-depositing aluminum onto one surface of a 12 μm thick biaxially oriented PET film as a hard plastic layer 1, attaching a 15 μm thick Ny film as a plastic protective layer 9 to the surface of the vapor-deposited layer 2 with an adhesive, and attaching a 140 μm thick LLDPE film as a flexible (non-strained) plastic layer 4 to the surface of the hard plastic layer 1 opposite to the vapor-deposited layer 2.

[0052] <Comparative Example 6> The laminate 10 of Comparative Example 6 was manufactured by forming a vapor-deposited layer 2 by vapor-depositing aluminum onto one surface of a 60 μm thick unoriented PET film as a plastic strain layer 3, attaching a 150 μm thick LLDPE film as a plastic flexible (non-strained) layer 4 to the surface of the vapor-deposited layer 2 with an adhesive, and attaching a 15 μm thick Ny film as a plastic protective layer 9 to the surface of the plastic strain layer 3 opposite to the vapor-deposited layer 2 with an adhesive.

[0053] <Comparative Example 7> The laminate 10 of Comparative Example 7 was prepared using the same method as in Comparative Example 1, except that a 60 μm thick unstretched PET film, which serves as a plastic strain layer 3, was further attached to the surface of the hard plastic layer 1 opposite to the vapor-deposited layer 2 using an adhesive.

[0054] [Evaluation of plastic separation] Each laminate prepared as described above in Examples 1-6 and Comparative Examples 1-7 was cut into small square pieces measuring 5 mm in length and width x 5 mm in length. Ten of these pieces were then individually immersed in a sodium hydroxide aqueous solution at 80°C for each example and comparative example. Visual inspection was performed to determine whether the plastic (at least one layer of plastic hard layer, plastic flexible (strained) layer, plastic flexible (unstrained) layer, plastic strained layer, and plastic protective layer) could be separated from each laminate within 15 minutes of immersion in the sodium hydroxide aqueous solution. The results are shown in Table 1.

[0055] [Table 1]

[0056] In the "Layer Composition" column of Table 1, "Hard Layer," "Flexible (Strained) Layer," "Flexible (Unstrained) Layer," "Strained Layer," and "Plastic Protective Layer" refer to "Plastic Hard Layer," "Plastic Flexible (Strained) Layer," "Plastic Flexible (Unstrained) Layer," "Plastic Strained Layer," and "Plastic Protective Layer," respectively. In addition, in the "Separation Ratio" column of Table 1, the denominator of the fraction represents the total number of small pieces in which plastic separation was performed, and the numerator of the fraction represents the number of small pieces in which plastic separation was confirmed within 15 minutes of immersion in the sodium hydroxide solution.

[0057] [Evaluation Results] As shown in Table 1, the laminates of Examples 1 to 6, which are included in the scope of the laminates of this disclosure, were found to allow for plastic separation in a shorter time compared to the laminates of Comparative Examples 1 to 7, which are not included in the scope of the laminates of this disclosure. Furthermore, it was confirmed that the laminates of Examples 1 to 6 allowed for plastic separation without the need to prepare a specific type of adhesive or a resin with a specific acid value, as was done in the past. Specifically, in Examples 1 and 2, the flexible (strained) layer and the rigid layer could be separated, while in Examples 3 to 6, the flexible (unstrained) layer could be separated. Therefore, it is considered that the laminates of Examples 1 to 6 can provide laminates that can reduce the time and effort required to separate plastic from the laminate. In particular, the separation of the plastic layer within 15 minutes of immersion in an aqueous sodium hydroxide solution is an extremely beneficial result for the recycling of the laminate.

[0058] As described above, embodiments and examples have been explained, but it is also planned from the outset that the configurations of each of the above embodiments and examples may be combined as appropriate.

[0059] The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Industrial applicability]

[0060] The laminates of this disclosure can be suitably used, for example, as laminates of packaging materials such as pouches. [Explanation of Symbols]

[0061] 1 Plastic rigid layer, 2 Vapor deposition layer, 2a First surface, 2b Second surface, 3 Plastic strain layer, 4 Plastic flexible layer, 5, 6, 7 Arrows, 9 Plastic protective layer, 10 Laminate, 11 Plastic flexible layer containing recycled material.

Claims

1. A laminate comprising a vapor-deposited layer, The vapor-deposited layer comprises a first surface and a second surface opposite to the first surface. The laminate further comprises, A hard plastic layer located on the first surface side of the vapor-deposited layer, having a storage modulus of 1000 MPa or more and 5000 MPa or less at 80°C, The system comprises a plastic soft layer located on the second surface side of the vapor-deposited layer, having a storage modulus of 30 MPa or more and 700 MPa or less at 80°C, A laminate that meets either requirement (1) or (2) below. (1) The plastic soft layer has a deformation property such that its shrinkage rate at 80°C is 2% or more and 50% or less. (2) The present invention further comprises a plastic strain layer located on the first surface side of the vapor-deposited layer and facing the vapor-deposited layer via the hard plastic layer, having a shrinkage rate of 2% or more and 50% or less at 80°C.

2. The laminate according to claim 1, wherein the hard plastic layer is in contact with the vapor-deposited layer.

3. The laminate according to claim 1, wherein the plastic flexible layer is a sealant layer.

4. The laminate according to claim 1, wherein the shortest distance between the plastic strain layer and the plastic soft layer is 30 μm or less.

5. The laminate according to claim 1, wherein the storage modulus of the plastic strain layer at 80°C is 30 MPa or more and 700 MPa or less.

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