Film manufacturing method and film

Abstract

To provide a method or the like for manufacturing a film again using a recycled raw material of a polyamide-based resin recovered from a film containing a polyamide-based resin.SOLUTION: The film manufacturing method includes the steps of: recovering a recycled raw material of a polyamide-based resin from a film containing a polyamide-based resin; and manufacturing a film using a film raw material obtained by mixing a recycled raw material of a polyamide-based resin and a virgin raw material of a polyamide-based resin.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a film and a film.

Background Art

[0002] Japanese Patent Publication No. 2018-534184 (Patent Document 1) discloses a method for separating a composition containing polyamide and polyethylene terephthalate. In this separation method, each of polyamide and polyethylene terephthalate is separated and recovered from the composition containing polyamide and polyethylene terephthalate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a method for manufacturing a high-quality film again using a recycled raw material of a polyamide-based resin recovered from a film containing a polyamide-based resin, and the like.

Means for Solving the Problems

[0005] A method for manufacturing a film according to an aspect of the present invention includes a step of recovering a recycled raw material of a polyamide-based resin from a film containing a polyamide-based resin, and a step of manufacturing a film using a film raw material obtained by mixing the recycled raw material of the polyamide-based resin and a virgin raw material of the polyamide-based resin.

[0006] The molecular weight of the recycled raw material is smaller than that of the virgin raw material. Therefore, it is difficult to produce a film of sufficient quality using only the recycled raw material. In the method for producing the present film, a film raw material obtained by mixing a recycled raw material of a polyamide-based resin and a virgin raw material of a polyamide-based resin is used for film production. Therefore, according to the method for producing the present film, since the molecular weight of the film raw material is maintained at a certain level, a film of high quality can be produced as compared with the case of using only the recycled raw material.

[0007] In the method for producing the above film, the step of recovering the recycled raw material of the polyamide-based resin may include the step of dissolving the polyamide-based resin contained in the film with a dissolving solution containing ethylene glycol.

[0008] In the method for producing the above film, the temperature of the dissolving solution at the time of dissolving the polyamide-based resin contained in the film may be 170 degrees or higher and 190 degrees or lower.

[0009] In the method for producing the above film, the film further contains a polyester-based resin or an olefin-based resin, and the method for producing the film further includes the step of recovering the recycled raw material of the polyester-based resin or the olefin-based resin from the film. The step of recovering the recycled raw material of the polyester-based resin or the olefin-based resin includes the step of filtering the mixture generated by dissolution with the dissolving solution. In the step of filtering the mixture, the temperature of the mixture may be substantially the same as the temperature of the dissolving solution at the time of dissolving the polyamide-based resin contained in the film.

[0010] If the temperature of the mixture drops significantly during the step of filtering the mixture, the polyamide resin will precipitate during the filtration of the mixture. As a result, the recycled raw material of the polyamide resin cannot be sufficiently recovered. In the method for producing this film, the temperature of the mixture in the step of filtering the mixture is substantially the same as the temperature of the solution during the dissolution of the polyamide resin contained in the film. Therefore, according to the method for producing this film, since the polyamide resin is less likely to precipitate during the filtration of the mixture, the recycled raw material of the polyamide resin can be sufficiently recovered.

[0011] The method for producing the film may further include a step of measuring the viscosity of the recycled raw material of the polyamide resin and a step of determining the mixing ratio of the recycled raw material of the polyamide resin and the virgin raw material of the polyamide resin based on the viscosity.

[0012] According to the method for producing this film, since the mixing ratio of the recycled raw material and the virgin raw material is determined based on the viscosity of the recycled raw material of the polyamide resin, a film raw material having a desired viscosity can be obtained.

[0013] In the above film raw material, when the weight of the virgin raw material of the polyamide resin is 100 parts, the weight of the recycled raw material of the polyamide resin may be 30 parts or less.

[0014] A film according to another aspect of the present invention includes a recycled raw material of a polyamide resin recovered from a film containing a polyamide resin and a virgin raw material of the polyamide resin.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a method for producing a high-quality film again using a recycled raw material of a polyamide resin recovered from a film containing a polyamide resin.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0018] [1. Outline] FIG. 1 is a diagram showing a cross section of the film 10. As shown in FIG. 1, the film 10 includes a polyester-based resin layer 100 and a polyamide-based resin layer 101. The polyamide-based resin layer 101 is laminated on the polyester-based resin layer 100. The polyester-based resin layer 100 and the polyamide-based resin layer 101 are adhered via an adhesive (not shown) such as a polyester-based elastomer.

[0019] The polyester-based resin layer 100 is composed of, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), or polybutylene naphthalate (PBN). The polyamide-based resin layer 101 is composed of, for example, nylon or aramid.

[0020] A laminated film including a plurality of types of layers such as the film 10 is generally known. Recycling such a laminated film is difficult. Generally, in a film produced using a recycled raw material obtained from a laminated film, for example, the appearance of the film deteriorates and the performance of the film decreases.

[0021] In the method for manufacturing a film according to the present embodiment, since improvements have been made, even if a recycled raw material of the polyamide resin recovered from the film is used, it is possible to manufacture a high-quality film again. Hereinafter, the method for manufacturing a film according to the present embodiment will be described in detail.

[0022] [2. Method for Manufacturing Film] FIG. 2 is a flowchart showing the manufacturing procedure of a film in the method for manufacturing a film according to the present embodiment. Each step shown in this flowchart is performed by a film manufacturing apparatus. In the method for manufacturing a film according to the present embodiment, first, each layer in the film 10 is separated, the recycled raw material of each layer is recovered, and a film is produced again using the recovered recycled raw material. This will be described in detail below.

[0023] Referring to FIG. 2, the manufacturing apparatus pulverizes the film 10 to be recycled (step S100). As a result, the film 10 becomes a number of film pieces 11 (FIG. 3). The manufacturing apparatus dissolves the film pieces 11 (step S110).

[0024] FIG. 3 is a diagram schematically showing a filtration system 20 included in the manufacturing apparatus. As shown in FIG. 3, the filtration system 20 includes filtration devices 200 and 210. The dissolution of the film pieces 11 is performed in the filtration device 200. That is, the filtration device 200 also functions as a dissolution furnace. A filter 202 is disposed at the lower end of the filtration device 200. The filter 202 is composed of, for example, a metal mesh. The wire diameter of this metal mesh is, for example, 50 μm - 150 μm. A valve 208 is provided below the filter 202. When the valve 208 is opened, the liquid in the filtration device 200 is discharged toward the filtration device 210.

[0025] The filtration device 200 contains the dissolution solution 204. The dissolution solution 204 contains ethylene glycol. The mass percentage of the film piece 11 in the dissolution solution 204 is 1 wt% - 30 wt%. The temperature of the dissolution solution 204 is 170°C - 190°C. The time for dissolution in the filtration device 200 is from 10 minutes to 30 minutes. The dissolution in the filtration device 200 is performed with the valve 208 closed.

[0026] The polyamide resin layer 101 dissolves in the dissolution solution 204, while the polyester resin layer 100 does not dissolve in the dissolution solution 204. Therefore, through the dissolution of the film piece 11, the polyamide resin layer 101 dissolves in the dissolution solution 204, while the polyester resin layer 100 does not dissolve in the dissolution solution 204.

[0027] Referring again to FIG. 2, the manufacturing apparatus performs rough filtration of the mixture (hereinafter, also simply referred to as "mixture") generated by dissolution with the dissolution solution 204, and recovers the recycled raw material of the polyester resin layer 100 (for example, PET) that did not dissolve in the dissolution solution 204 (step S120).

[0028] Referring again to FIG. 3, the rough filtration of the mixture is performed by opening the valve 208 after the dissolution of the film piece 11. When the valve 208 is opened, the polyamide resin layer 101 passes through the filter 202 in a state of being dissolved in the dissolution solution 204 and is discharged toward the filtration device 210. On the other hand, the polyester resin layer 100 is collected by the filter 202. Thereby, the recycled raw material of the polyester resin layer 100 is recovered.

[0029] Note that the temperature of the mixture during rough filtration is substantially the same as the temperature during dissolution with the dissolution liquid 204. The reason why the temperature of the mixture is not intentionally lowered during rough filtration will be described below. If the temperature of the mixture significantly decreases during the step of rough filtering the mixture, polyamide-based resin will precipitate during the rough filtration of the mixture. As a result, the regeneration raw material of some polyamide-based resin will be trapped by the filter 202, and the regeneration raw material of the polyamide-based resin will not be sufficiently recovered in the subsequent steps. In the method for manufacturing a film according to the present embodiment, the temperature of the mixture in the step of rough filtering the mixture is substantially the same as the temperature of the dissolution liquid 204 when dissolving the polyamide-based resin layer 101 contained in the film piece 11. Therefore, according to this method for manufacturing a film, since the polyamide-based resin is less likely to precipitate during the rough filtration of the mixture, the regeneration raw material of the polyamide-based resin can be sufficiently recovered.

[0030] Referring again to FIG. 2, the manufacturing apparatus filters the mixture after rough filtration and recovers the regeneration raw material of the polyester-based resin layer 100 (step S130).

[0031] Referring again to FIG. 3, the filtration of the mixture is performed in the filtration apparatus 210. A filter 212 is disposed at the lower end of the filtration apparatus 210. The filter 212 is composed of, for example, filter paper. The mesh of the filter 212 is finer than that of the filter 202. A valve 218 is provided below the filter 212. When the valve 218 is opened, the liquid in the filtration apparatus 210 is discharged toward the outside of the filtration apparatus 210.

[0032] In step S130 of FIG. 2, first, with the valve 218 closed, the temperature of the mixture is lowered. As a result, in the filtration device 210, the polyamide resin precipitates. For example, when the temperature of the mixture becomes 160° C. or lower, the polyamide resin recrystallizes. Then, the valve 218 is opened. As a result, the solution 204 containing ethylene glycol passes through the filter 212 and is discharged toward the outside of the filtration device 210. On the other hand, the recrystallized polyamide resin is collected by the filter 212. Thereby, the regeneration raw material of the polyamide resin is recovered. The solution 204 (ethylene glycol) discharged to the outside of the filtration device 210 is reused, for example, after being distilled.

[0033] Referring again to FIG. 2, the manufacturing apparatus washes each of the regeneration raw material of the polyester resin recovered in step S120 and the regeneration raw material of the polyamide resin recovered in step S130 (step S140).

[0034] FIG. 4 is a diagram for explaining the washing procedure of the regeneration raw material (polyester resin pieces 13) of the polyester resin, and FIG. 5 is a diagram for explaining the washing procedure of the regeneration raw material (polyamide resin precipitate 12) of the polyamide resin. As shown in FIGS. 4 and 5, each regeneration raw material is washed, for example, with pure water 206 in the filtration device 200. That is, the filtration device 200 also functions as a washing kiln. Then, filtration is performed and the regeneration raw material is dried. Thereby, the washing of each regeneration raw material is completed.

[0035] Referring again to FIG. 2, the manufacturing apparatus pelletizes each of the regeneration raw material of the polyester resin after washing and the regeneration raw material of the polyamide resin after washing (step S150). The manufacturing apparatus measures the viscosity of each of the pelletized regeneration raw material of the polyester resin and the pelletized regeneration raw material of the polyamide resin (step S160). The viscosity is measured by a known method.

[0036] As described above, the manufacturing apparatus manufactures a film again using the recycled raw materials of each layer of the film 10. However, the molecular weight of the recycled raw materials is smaller than that of the virgin raw materials. Therefore, it is difficult to manufacture a film of sufficient quality using only the recycled raw materials. In the method for manufacturing a film according to the present embodiment, a film raw material obtained by mixing a recycled raw material of a polyamide-based resin and a virgin raw material of a polyamide-based resin is used for manufacturing the film. Further, a film raw material obtained by mixing a recycled raw material of a polyester-based resin and a virgin raw material of a polyester-based resin is used for manufacturing the film. Therefore, according to the method for manufacturing a film according to the present embodiment, since the molecular weight of the film raw material is maintained at a certain level, a film of higher quality can be manufactured as compared with the case of using only the recycled raw materials.

[0037] The manufacturing apparatus determines the mixing ratio of the recycled raw material and the virgin raw material for the polyester-based resin based on the viscosity of the recycled raw material of the polyester-based resin, and determines the mixing ratio of the recycled raw material and the virgin raw material for the polyamide-based resin based on the viscosity of the recycled raw material of the polyamide-based resin (step S170). That is, here, the mixing ratio of the recycled raw material and the virgin raw material is determined so that the viscosity of the film raw material used for each layer of the newly produced film becomes the desired viscosity. For example, when the weight of the virgin raw material of the polyamide-based resin is 100 parts, a mixing ratio is determined such that the weight of the recycled raw material of the polyamide-based resin is 30 parts or less.

[0038] The manufacturing apparatus mixes virgin raw material and recycled raw material for the polyamide - based resin based on the mixing ratio determined in step S170. Also, the manufacturing apparatus mixes virgin raw material and recycled raw material for the polyester - based resin based on the mixing ratio determined in step S170. The manufacturing apparatus manufactures a film including a polyamide - based resin layer and a polyester - based resin layer using the mixed polyamide - based resin and the mixed polyester - based resin (step S180). The film thus manufactured contains the recycled raw material of the polyamide - based resin recovered from the film 10 containing the polyamide - based resin and the virgin raw material of the polyamide - based resin. Also, this film contains the recycled raw material of the polyester - based resin recovered from the film 10 and the virgin raw material of the polyester - based resin.

[0039] [3. Features] As described above, the method for manufacturing a film according to the present embodiment includes a step of recovering the recycled raw material of the polyamide - based resin from the film containing the polyamide - based resin, and a step of manufacturing a film using a film raw material obtained by mixing the recycled raw material of the polyamide - based resin and the virgin raw material of the polyamide - based resin. Thus, in the method for manufacturing a film according to the present embodiment, the film raw material obtained by mixing the recycled raw material of the polyamide - based resin and the virgin raw material of the polyamide - based resin is used for manufacturing the film. Therefore, according to the method for manufacturing a film according to the present embodiment, since the molecular weight of the film raw material is maintained at a certain level, a film of higher quality can be manufactured as compared with the case of using only the recycled raw material.

[0040] [4. Modifications] Although the embodiments have been described above, the present invention is not limited to the above - described embodiments, and various modifications are possible without departing from the gist thereof. Modifications will be described below.

[0041] <4 - 1> In the above embodiment, the film 10 included the polyester resin layer 100, but an olefin resin layer may be included instead of the polyester resin layer 100. The olefin resin layer may be composed of, for example, polyethylene or polypropylene.

[0042] <4-2> In the above embodiment, the recycled raw materials of each of the polyamide resin layer 101 and the polyester resin layer 100 were used again in the production of the film. However, the recycled raw materials of each of the polyamide resin layer 101 and the polyester resin layer 100 do not necessarily have to be used again in the production of the film. At least, the recycled raw material of the polyamide resin layer 101 may be used again in the production of the film.

[0043] <4-3> In the above embodiment, based on the film 10, a film having a polyamide resin layer and a polyester resin layer again was produced. However, the configuration of the film produced based on the film 10 is not limited to this. For example, a single-layer film having only a polyamide resin layer may be produced, or a laminated film having a polyamide resin layer and a resin layer other than the polyester resin layer may be produced.

[0044] <4-4> In the above embodiment, dissolution and washing were performed in a common kiln (filter device 200). However, dissolution and washing may be performed in separate kilns.

Explanation of Reference Numerals

[0045] 10 Film, 11 Film piece, 12 Polyamide resin precipitate, 13 Polyester resin piece, 20 Filtration system, 100 Polyester resin layer, 101 Polyamide resin layer, 200, 210 Filter device, 202, 212 Filter, 204 Dissolution solution, 206 Pure water, 208, 218 Valve.

Claims

1. A step of recovering a recycled raw material of a polyamide resin from a film containing a polyamide resin, and A step of manufacturing a film using a film raw material obtained by mixing the recycled raw material of the polyamide resin and a virgin raw material of the polyamide resin. A method for manufacturing a film comprising the steps.

2. The step of recovering the recycled raw material of the polyamide resin includes a step of dissolving the polyamide resin contained in the film with a solution containing ethylene glycol. The method for manufacturing a film according to Claim 1.

3. The temperature of the solution at the time of dissolving the polyamide resin contained in the film is 170 degrees or more and 190 degrees or less. The method for manufacturing a film according to Claim 2.

4. The film further contains a polyester resin or an olefin resin, The method for manufacturing the film further includes a step of recovering a recycled raw material of the polyester resin or the olefin resin from the film, The step of recovering the recycled raw material of the polyester resin or the olefin resin includes a step of filtering the mixture generated by dissolution with the solution, In the step of filtering the mixture, the temperature of the mixture is substantially the same as the temperature of the solution at the time of dissolving the polyamide resin contained in the film. The method for manufacturing a film according to Claim 3.

5. A step of measuring the viscosity of the recycled raw material of the polyamide resin, and Based on the viscosity, a step of determining a mixing ratio of the recycled raw material of the polyamide resin and the virgin raw material of the polyamide resin. The method for manufacturing a film according to any one of Claims 1 to 4.

6. In the film raw material, when the weight of the virgin raw material of the polyamide resin is 100 parts, the weight of the recycled raw material of the polyamide resin is 30 parts or less. The method for manufacturing a film according to any one of Claims 1 to 5.

7. A recycled raw material of a polyamide resin recovered from a film containing a polyamide resin, and A film containing a virgin raw material of a polyamide resin.

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