Method for separating laminates

Abstract

The primary objective is to propose a method for separating laminates that enables material recycling by separating each layer from the laminate, even if the laminate is a thick, batch-type laminate made solely of thermoplastic resin, in the shape of a flat plate or a rain gutter. [Solution] A method for separating each layer in a laminate having a total thickness of 0.5 mm or more, comprising a core material layer, a surface resin layer provided on at least one side of the core material layer, and an adhesive resin layer provided between the core material layer and the surface resin layer, comprising the steps of heating the laminate and separating the surface resin layer and the core material layer by the shear force of a pair of rolls, wherein when the clearance between the pair of rolls is C mm, the thickness of the core material layer is t1 mm, and the total thickness of the laminate is t2 mm, formula 1:t1

Description

Technical Field

[0001] The present invention relates to a method for separating a laminate. More specifically, the present invention mainly relates to a method for separating each layer from a laminate including a resin layer and reusing it.

Background Art

[0002] In order to realize a resource recycling society, as one method of reducing waste, the reuse of defective products and the like generated in the manufacturing process of molded products is required. Recycling methods such as thermal recycling and chemical recycling can be mentioned, but from the viewpoint of reducing environmental load, reuse by material recycling is the most direct method.

[0003] In the material recycling of composite members such as a laminate composed of a plurality of resin layers or a laminate including a resin layer and a metal layer, it is necessary to separate each layer of the laminate. Patent Document 1 discloses a method of separating a surface layer by applying a shearing force to a laminated film in which a surface layer is laminated via an adhesive resin layer by sending the laminated film through a gap between nip rolls having different peripheral speeds. Patent Document 2 discloses a method of separating a vinyl chloride-based resin and a metal by passing a composite of a vinyl chloride-based resin and a metal through a pair of rolls having unevenness and being meshing after preheating.

[0004] Patent Document 3 discloses a method of separating a surface resin layer from a substrate film layer by bringing a transfer material that thermally adheres to a surface film layer of a laminated film made of different materials into contact with the surface film layer under heating and pressure, causing the surface resin layer to migrate to the transfer material side and peel off. Patent Document 4 discloses a method of separating a resin or rubber from a metal surface by induction heating a metal portion of a composite member formed by joining a resin or rubber and a metal, partially changing the properties of the resin or rubber to weaken the adhesive force, and using a pair of rolling rolls.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 63-202409 [Patent Document 2] Japanese Patent Application Publication No. 9-174550 [Patent Document 3] Japanese Patent Application Publication No. 10-34650 [Patent Document 4] Japanese Patent Publication No. 2003-260437 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, while conventional technologies such as those described in Patent Documents 1 to 4 are applicable to long laminated films, flexible laminated films, and composite members containing metal, they are difficult to apply to thick laminates made solely of thermoplastic resin that are in the shape of a flat plate or a rain gutter and are in a batch type.

[0007] The present invention was made to solve the aforementioned problems, and its main objective is to propose a method for separating laminates that enables material recycling by separating each layer from the laminate, even if the laminate is a thick laminate made only of thermoplastic resin, in the shape of a flat plate or a rain gutter, and in a batch type. [Means for solving the problem]

[0008] This disclosure includes the following components: [1] A method for separating each layer in a laminate having a total thickness of 0.5 mm or more, comprising a core material layer, a surface resin layer provided on at least one side of the core material layer, and an adhesive resin layer provided between the core material layer and the surface resin layer, The process includes the steps of heating the laminate and separating the surface resin layer and the core material layer by the shear force of a pair of rolls, When the clearance between the pair of rolls is C mm, the thickness of the core material layer is t1 mm, and the total thickness of the laminate is t2 mm, a method for separating a laminate that satisfies Formula 1: t1 < C < t2 × 0.90. [2] In the step of heating the laminate, the laminate is heated to 100 to 140°C, the method for separating a laminate according to [1] above. [3] The surface temperature of the pair of rolls is 40 to 120°C, the method for separating a laminate according to [1] or [2] above. [4] The surface resin layer contains a vinyl chloride resin, the method for separating a laminate according to any one of [1] to [3] above. [5] The adhesive resin layer has a melting point of the adhesive resin constituting the adhesive resin layer of 170°C or lower, the method for separating a laminate according to any one of [1] to [4] above. [6] The core material layer contains polyethylene terephthalate, the method for separating a laminate according to any one of [1] to [5] above. [7] In the step of heating the laminate, the laminate is heated by a hot air method, a hot plate method, a far infrared method, a near infrared method, or high frequency induction heating, the method for separating a laminate according to any one of [1] to [6] above.

Advantages of the Invention

[0009] According to the present invention, even if it is a thick laminate made only of a thermoplastic resin that is in a flat plate shape or a rain gutter shape and is of a batch type, a method for separating a laminate that enables separation of each layer from the laminate and material recycling is provided.

Brief Description of the Drawings

[0010] [Figure 1] It is a cross-sectional view showing an example of a laminate to be applied to the separation method according to the embodiment. [Figure 2] It is a schematic diagram for explaining the method for separating a laminate according to an example of the embodiment. [Figure 3] It is a cross-sectional view showing an example of a laminate to be applied to the separation method according to the embodiment.

Modes for Carrying Out the Invention

[0011] Hereinafter, a method for separating a laminate according to an example of an embodiment will be described while referring to the drawings. Note that the dimensions and the like of the drawings illustrated in the following description are merely examples, and the present invention is not necessarily limited thereto, and can be appropriately modified and implemented without changing the gist thereof.

[0012] The method for separating a laminate according to the embodiment includes a core material layer, a surface resin layer provided on at least one side of the core material layer, and an adhesive resin layer provided between the core material layer and the surface resin layer, and is a method for separating each layer in a laminate having a total thickness of 0.5 mm or more.

[0013] (Laminate) The laminate to which the separation method according to the embodiment is applied is typically a laminate in which surface resin layers are provided via adhesive resin layers on both sides in the thickness direction of the core material layer, but is not limited to this mode. The laminate may be one in which a surface resin layer is provided via an adhesive resin layer only on one side in the thickness direction of the core material layer.

[0014] FIG. 1 is a cross-sectional view showing an example of a laminate to which the separation method according to the embodiment is applied. A laminate 1 of an example shown in FIG. 1 includes a core material layer 2, surface resin layers 3 provided on both sides in the thickness direction of the core material layer 2, and adhesive resin layers 4 provided between the core material layer 2 and the respective surface resin layers 3. Note that the laminate is not limited to a flat plate shape, and may be a gutter-shaped laminate 1 as shown in FIG. 3.

[0015] The core material layer 2, the surface resin layer 3, and the adhesive resin layer 4 in the laminate are all resin layers.

[0016] As the core material layer 2, for example, a thermoplastic resin sheet can be used. Examples of the resin constituting the core material layer 2 include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyglycolic acid, poly(L-lactic acid), poly(3-hydroxybutyrate), poly(3-hydroxybutyrate / hydroxyvalerate), poly(ε-caprolactone), polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate / lactic acid, polybutylene succinate / carbonate, polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethylene adipate / terephthalate, polybutylene succinate / adipate / terephthalate, etc. Since it has high heat resistance, it is easy to maintain the strength of the laminate, and also because the separation between the core material layer and the surface resin layer is easy in the separation process described later, the core material layer 2 preferably contains a polyester-based resin, and more preferably contains polyethylene terephthalate (PET). The resin contained in the core material layer 2 may be one kind or two or more kinds. As the core material layer 2, a PET sheet is preferable, and a uniaxially stretched PET sheet is more preferable.

[0017] The melting point of the resin constituting the core material layer 2 is preferably 200 °C or higher, more preferably 220 °C or higher, and even more preferably 250 °C or higher in order not to soften in the heating process. If the melting point of the resin constituting the core material layer 2 is at or above the lower limit value, it is easy to maintain the strength of the laminate, and also the separation between the core material layer and the surface resin layer becomes easy in the separation process described later. The melting point of the resin means a value measured according to a differential scanning calorimeter (DSC).

[0018] The thickness t1 of the core material layer 2 is preferably 0.3 mm or more, more preferably 0.4 mm or more, and even more preferably 0.5 mm or more. If the thickness t1 of the core material layer 2 is at or above the lower limit value, it is easy to maintain the strength of the laminate, and also the separation between the core material layer and the surface resin layer becomes easy in the separation process described later. Also, the thickness t1 of the core material layer 2 is preferably 0.7 mm or less.

[0019] Examples of resins that make up the surface resin layer 3 include polyvinyl chloride resin, AES resin, and ASA resin. The resin contained in the surface resin layer 3 may be one type or two or more types.

[0020] The glass transition temperature of the resin constituting the surface resin layer 3 is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. If the melting point of the resin constituting the surface resin layer 3 is below the above upper limit, the separation of the core material layer and the surface resin layer will be easier in the separation process described later. Furthermore, the glass transition temperature of the resin constituting the surface resin layer 3 is preferably 60°C or higher. The glass transition temperature of the aforementioned resin refers to the value measured according to differential scanning calorimeter (DSC) or dynamic viscoelastic evaluation.

[0021] The thickness of the surface resin layer 3 is preferably 1 mm or less, more preferably 0.8 mm or less, and even more preferably 0.5 mm or less. If the thickness of the surface resin layer 3 is less than or equal to the above upper limit, the separation of the core material layer and the surface resin layer will be easier in the separation process described later. Furthermore, the thickness of the surface resin layer 3 is preferably 0.2 mm or more. When surface resin layers 3 are provided on both sides of the core material layer 2 in the thickness direction, the thicknesses of the two surface resin layers 3 may be the same or different.

[0022] Examples of adhesive resins constituting the adhesive resin layer 4 include one or more adhesives selected from the group consisting of polyester elastomers, styrene elastomers, olefin elastomers, epoxy, urethane, polyester, and rubber-based adhesives.

[0023] The melting point of the adhesive resin is preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower. If the melting point of the adhesive resin is below the above upper limit, the separation of the core material layer and the surface resin layer in the separation process described later will be easier. Furthermore, the melting point of the adhesive resin is preferably 100°C or higher. The melting point of the adhesive resin refers to the value measured according to a differential scanning calorimetry (DSC).

[0024] The thickness of the adhesive resin layer 4 is preferably 0.5 mm or less, more preferably 0.2 mm or less, and even more preferably 0.1 mm or less.

[0025] The total thickness t2 of the laminate 1 is 0.5 mm or more, preferably 1.0 mm or more, and more preferably 1.5 mm or more. If the total thickness t2 of the laminate 1 is equal to or greater than the lower limit, it is easier to maintain the strength of the laminate, and the separation of the core material layer and the surface resin layer in the separation process described later becomes easier. Furthermore, the total thickness t2 of the laminate 1 is preferably 2.0 mm or less.

[0026] The shape of the laminate to which the separation method according to the embodiment is applied is a flat plate shape in the example shown in Figure 1, but is not limited to that, and may also be a rain gutter shape. The separation method for laminates according to the embodiment can also be applied to laminates with a total thickness of 0.5 mm or more, in the shape of a flat plate or rain gutter, and each layer can be separated from the laminate for material recycling.

[0027] (Separation method) The method for separating the laminate according to the embodiment includes the following heating step and separation step. Heating process: The laminate is heated. Separation process: The surface resin layer and the core material layer in the laminate are separated by the shear force of a pair of rolls.

[0028] For example, in the case of a rain gutter-shaped laminate, it is preferable to make an incision in a part of the surface resin layer to create a separation point in order to facilitate the separation of the surface resin layer and the core material layer before the heating process. It is preferable to form this incision in the surface resin layer of the end on the side that first comes into contact with the pair of rolls in the laminate during the separation process.

[0029] <Heating process> In the heating process, the laminate is heated to soften the surface resin layer. The heating temperature of the laminate in the heating process can be above the glass transition temperature of the resin constituting the surface resin layer, and below the melting point of the resin constituting the core material layer. In addition, the adhesive resin layer can be heated to near its melting point, resulting in a state where the adhesive strength is reduced.

[0030] In the heating step, the heating temperature of the laminate is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher. If the heating temperature of the laminate is at or above the lower limit value, separation between the core material layer and the surface resin layer in the separation step described later becomes easier. Further, the heating temperature of the laminate in the heating step is preferably 140°C or lower.

[0031] The method of heating the laminate is not particularly limited, and examples include a hot air method, a hot plate method, a far-infrared method, a near-infrared method, and high-frequency induction heating. Examples of the hot air method include heating using an oven, a jet furnace, etc. Examples of the hot plate method include a heating press, etc.

[0032] <Separation step> In the separation step, the laminate after the heating step is passed between a pair of rolls with a clearance narrower than the total thickness of the laminate. More specifically, in the separation step, when the clearance between the pair of rolls is C mm, the thickness of the core material layer is t1 mm, and the total thickness of the laminate is t2 mm, the laminate after the heating step is passed between the pair of rolls so as to satisfy Formula 1: t1 < C < t2 × 0.90.

[0033] For example, in the case of the laminate 1 in the example shown in FIG. 1, as shown in FIG. 2, the clearance between the pair of rolls 5 and ⑥ is set so as to satisfy Formula 1: t1 < C < t2 × 0.90, and the laminate 1 after the heating step is passed between the pair of rolls 5 and ⑥. At this time, near the inlet of the pair of rolls 5 and ⑥, a resin lump 7 made of the resin constituting the surface resin layer 3 is generated, and shear occurs between the core material layer and the surface resin layer at the location where the clearance between the pair of rolls 5 and ⑥ is the narrowest. Thereby, the surface resin layer 3 and the core material layer 2 of the laminate 1 are separated by the shearing force of the pair of rolls 5 and ⑥.

[0034] The surface temperature of the pair of rolls in the separation process (roll temperature) is preferably 40°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. If the roll temperature is above the lower limit, the separation of the core material layer and the surface resin layer becomes easier. Furthermore, a roll temperature of 120°C or lower is preferable.

[0035] As described above, in the laminate separation method according to the embodiment, the laminate is preheated and then passed between a pair of rolls to satisfy the conditions of Equation 1. As a result, the adhesive strength of the adhesive resin layer is reduced by heating, and shearing is applied by the pair of rolls, so that even if the laminate is in the shape of a flat plate or a rain gutter and has a batch-type total thickness of 0.5 mm or more, the surface resin layer and the core material layer can be separated. In this way, even thick laminates used in rain gutters and the like can be easily separated from the surface resin layer and core material layer for material recycling. [Examples]

[0036] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0037] [Experimental Example 1] For testing, a rain gutter-shaped laminate was prepared, measuring 360 mm in width, 1.4 m in length, and with a total thickness (t2) of 1.5 mm. This laminate consisted of a 0.5 mm thick (t1) core layer made of polyethylene terephthalate (PET), with surface resin layers made of polyvinyl chloride resin laminated on both sides via an adhesive resin layer with a melting point of 170°C or lower. A pair of rolls with a diameter of 260 mm and a width of 400 m were used, with a roll clearance (C) of 0.7 mm, a roll temperature of 75°C, and a roll rotation speed of 5.0 m / min. A longitudinal cut was made at the end of the surface resin layer of the laminate, and after heating to 120°C in a heating oven, the laminate was passed between the pair of rolls to confirm its separation state. The separation state was evaluated according to the following evaluation criteria. <Evaluation Criteria> ○: The surface resin layer was peeled off in an area of ​​95% or more of the total surface area of ​​the surface resin layer. △: The surface resin layer was peeled off within the range of more than 0% and less than 95% of the total surface area of the surface of the surface resin layer. ×: The surface resin layer was not peeled off at all.

[0038] [Experimental Examples 2 to 12] The laminate was passed between a pair of rolls in the same manner as in Experimental Example 1 except that the clearance between the pair of rolls and the roll temperature were changed as shown in Table 1, and the separation state was confirmed and evaluated.

[0039] Table 1 shows the evaluation results of the clearance between a pair of rolls, the roll temperature, and the separation state in Experimental Examples 1 to 12.

[0040]

Table 1

[0041] As shown in Table 1, in Experimental Examples 1 to 7, 9 to 10, and 12 that satisfy the condition of Formula 1: t1 < C < t2 × 0.90, the laminate was heated to soften the surface resin layer and the adhesive resin layer, and a shearing force was applied by passing it between a pair of rolls, so that even in the case of a laminated body having a gutter shape with a thick wall, the core material layer and the surface resin layer could be separated. On the other hand, in Experimental Examples 8 and 11 that do not satisfy the condition of Formula 1, the core material layer and the surface resin layer could not be separated.

Explanation of Reference Signs

[0042] 1 Laminate 2 Core material layer 3 Surface resin layer [[ID=�¬]] 4 Adhesive resin layer 5, 6 A pair of rolls 7 Resin pool

Claims

1. A method for separating each layer in a laminate having a total thickness of 0.5 mm or more, comprising a core material layer, a surface resin layer provided on at least one side of the core material layer, and an adhesive resin layer provided between the core material layer and the surface resin layer, The process includes the steps of heating the laminate and separating the surface resin layer and the core material layer by the shear force of a pair of rolls, A method for separating a laminate, where C mm is the clearance between the pair of rolls, t1 mm is the thickness of the core material layer, and t2 mm is the total thickness of the laminate, and equation 1: t1 < C < t2 × 0.90 is satisfied.

2. The method for separating a laminate according to claim 1, wherein in the step of heating the laminate, the laminate is heated to 100 to 140°C.

3. The method for separating a laminate according to claim 1 or 2, wherein the surface temperature of the pair of rolls is 40 to 120°C.

4. The method for separating a laminate according to claim 1 or 2, wherein the surface resin layer comprises a polyvinyl chloride resin.

5. The method for separating a laminate according to claim 1 or 2, wherein the adhesive resin layer has a melting point of 170°C or less.

6. The method for separating a laminate according to claim 1 or 2, wherein the core material layer comprises polyethylene terephthalate.

7. The method for separating a laminate according to claim 1 or 2, wherein in the step of heating the laminate, the laminate is heated by a hot air method, a hot plate method, a far-infrared method, a near-infrared method, or a high-frequency induction heating method.

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