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 producing a film and a film. [Background technology]

[0002] JP 2018-534184 A (Patent Document 1) discloses a method for separating a composition containing polyamide and polyethylene terephthalate. In this separation method, polyamide and polyethylene terephthalate are each separated and recovered from a composition containing polyamide and polyethylene terephthalate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-534184 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for producing a high-quality film again using recycled raw material of polyamide-based resin recovered from a film containing a polyamide-based resin. [Means for solving the problem]

[0005] A method for producing a film according to one aspect of the present invention includes the steps of recovering recycled raw polyamide-based resin from a film containing a polyamide-based resin, and producing a film using a film raw material that is a mixture of the recycled raw polyamide-based resin and virgin raw 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 recycled raw materials. In the present film manufacturing method, a film raw material that is a mixture of recycled raw material of polyamide resin and virgin raw material of polyamide resin is used for film production. Therefore, according to the present film manufacturing method, the molecular weight of the film raw material is maintained at a certain level, so that a film of higher quality can be produced compared to the case where only recycled raw materials are used.

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

[0008] In the above-mentioned method for producing a film, the temperature of the dissolving solution when dissolving the polyamide resin contained in the film may be 170° C. or more and 190° C. or less.

[0009] In the above-mentioned film manufacturing method, the film further contains a polyester-based resin or an olefin-based resin, and the film manufacturing method further includes a step of recovering recycled raw materials of the polyester-based resin or the olefin-based resin from the film, and the step of recovering the recycled raw materials of the polyester-based resin or the olefin-based resin includes a step of filtering the mixture produced by dissolution with a dissolving liquid, and in the step of filtering the mixture, the temperature of the mixture may be approximately the same as the temperature of the dissolving liquid when dissolving the polyamide-based resin contained in the film.

[0010] If the temperature of the mixture is significantly reduced in 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 will not be sufficiently recovered. In the present film manufacturing method, the temperature of the mixture in the step of filtering the mixture is approximately the same as the temperature of the dissolving solution when dissolving the polyamide resin contained in the film. Therefore, according to the present film manufacturing method, the polyamide resin is less likely to precipitate during the filtration of the mixture, and the recycled raw material of the polyamide resin can be sufficiently recovered.

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

[0012] According to the present film manufacturing method, the mixing ratio of recycled and virgin raw materials is determined based on the viscosity of the recycled polyamide resin raw material, so that a film raw material with the desired viscosity can be obtained.

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

[0014] A film according to another aspect of the present invention comprises recycled raw material of polyamide-based resin recovered from a film containing polyamide-based resin, and virgin raw material of polyamide-based resin. Effect of the Invention

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

[0016] [Figure 1] FIG. 2 is a cross-sectional view of a film. [Diagram 2] 1 is a flowchart showing a film manufacturing procedure. [Diagram 3] FIG. 1 is a schematic diagram of a filtration system. [Figure 4] FIG. 2 is a diagram for explaining the washing procedure of recycled raw material of polyester-based resin. [Diagram 5] FIG. 2 is a diagram for explaining the washing procedure of recycled raw material of polyamide-based resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0018] [1. Overview] Fig. 1 is a diagram showing a cross section of a 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 bonded together via an adhesive (not shown) such as a polyester-based elastomer.

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

[0020] Laminated films containing multiple layers, such as film 10, are commonly known. Recycling of such laminated films is difficult because, in general, films produced using recycled raw materials obtained from the laminated films suffer from, for example, poor appearance and poor performance.

[0021] The film manufacturing method according to the present embodiment is so devised that it is possible to manufacture high quality films again using recycled raw material polyamide resin recovered from films. The film manufacturing method according to the present embodiment will be described in detail below.

[0022] [2. Film manufacturing method] FIG. 2 is a flow chart showing the film manufacturing procedure in the film manufacturing method according to the present embodiment. Each step shown in this flow chart is performed by a film manufacturing device. In the film manufacturing method according to the present embodiment, first, each layer of the film 10 is separated, the recycled raw materials of each layer are recovered, and the film is remanufactured using the recovered recycled raw materials. A detailed description is given below.

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

[0024] FIG. 3 is a diagram showing a schematic diagram of 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 film piece 11 is dissolved in the filtration device 200. That is, the filtration device 200 also functions as a melting furnace. A filter 202 is disposed at the lower end of the filtration device 200. The filter 202 is made of, for example, a metal mesh. The wire diameter of this metal mesh is, for example, 50 μm to 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 a dissolving liquid 204. The dissolving liquid 204 contains ethylene glycol. The mass percentage of the film pieces 11 in the dissolving liquid 204 is 1 wt%-30 wt%. The temperature of the dissolving liquid 204 is 170°C-190°C. The time for dissolving in the filtration device 200 is 10 to 30 minutes. The dissolving in the filtration device 200 is performed with the valve 208 closed.

[0026] The polyamide-based resin layer 101 dissolves in the dissolving liquid 204, whereas the polyester-based resin layer 100 does not dissolve in the dissolving liquid 204. Therefore, as the film piece 11 dissolves, the polyamide-based resin layer 101 dissolves in the dissolving liquid 204, whereas the polyester-based resin layer 100 does not dissolve in the dissolving liquid 204.

[0027] Referring again to FIG. 2, the manufacturing apparatus performs coarse filtration of the mixture (hereinafter also simply referred to as the "mixture") produced by dissolution with the dissolving liquid 204, and recovers recycled raw material of the polyester-based resin layer 100 (e.g., PET) that did not dissolve in the dissolving liquid 204 (step S120).

[0028] 3, coarse filtration of the mixture is performed by opening valve 208 after dissolving film pieces 11. When valve 208 is opened, polyamide-based resin layer 101 in a dissolved state in dissolving liquid 204 passes through filter 202 and is discharged toward filtration device 210. Meanwhile, polyester-based resin layer 100 is collected by filter 202. In this way, recycled raw material of polyester-based resin layer 100 is recovered.

[0029] The temperature of the mixture during the coarse filtration is approximately the same as the temperature when the mixture is dissolved by the dissolving liquid 204. The reason why the temperature of the mixture is not intentionally lowered during the coarse filtration will be described below. If the temperature of the mixture is significantly lowered in the process of coarsely filtering the mixture, the polyamide resin will precipitate during the coarse filtration of the mixture. As a result, some of the recycled raw material of the polyamide resin will be collected by the filter 202, and the recycled raw material of the polyamide resin will not be sufficiently recovered in the subsequent process. In the film manufacturing method according to the present embodiment, the temperature of the mixture during the process of coarsely filtering the mixture is approximately the same as the temperature of the dissolving liquid 204 when the polyamide resin layer 101 contained in the film piece 11 is dissolved. Therefore, according to this film manufacturing method, the polyamide resin is unlikely to precipitate during the coarse filtration of the mixture, so that the recycled raw material of the polyamide resin can be sufficiently recovered.

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

[0031] Referring again to Fig. 3, the mixture is filtered in the filtration device 210. A filter 212 is disposed at the lower end of the filtration device 210. The filter 212 is made 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 device 210 is discharged toward the outside of the filtration device 210.

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

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

[0034] FIG. 4 is a diagram for explaining the washing procedure of recycled raw materials of polyester resin (polyester resin pieces 13), and FIG. 5 is a diagram for explaining the washing procedure of recycled raw materials of polyamide resin (polyamide resin precipitates 12). As shown in FIG. 4 and FIG. 5, each recycled raw material is washed, for example, in a filtering device 200 filled with pure water 206. That is, the filtering device 200 also functions as a washing furnace. Thereafter, filtration is performed, and the recycled raw materials are dried. This completes the washing of each recycled raw material.

[0035] 2, the manufacturing apparatus pelletizes each of the washed recycled raw material of polyester-based resin and the washed recycled raw material of polyamide-based resin (step S150). The manufacturing apparatus measures the viscosity of each of the pelletized recycled raw material of polyester-based resin and the pelletized recycled raw material of polyamide-based resin (step S160). The viscosity is measured by a known method.

[0036] As described above, the manufacturing device manufactures the 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 film manufacturing method according to the present embodiment, a film raw material that is a mixture of recycled raw materials of polyamide-based resin and virgin raw materials of polyamide-based resin is used for manufacturing the film. Also, a film raw material that is a mixture of recycled raw materials of polyester-based resin and virgin raw materials of polyester-based resin is used for manufacturing the film. Therefore, according to the film manufacturing method according to the present embodiment, the molecular weight of the film raw materials is maintained at a certain level, so that a film of higher quality can be manufactured compared to the case where only recycled raw materials are used.

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

[0038] The manufacturing apparatus mixes virgin raw materials and recycled raw materials for the polyamide-based resin based on the mixing ratio determined in step S170. The manufacturing apparatus also mixes virgin raw materials and recycled raw materials for the polyester-based resin based on the mixing ratio determined in step S170. The manufacturing apparatus uses the mixed polyamide-based resin and the mixed polyester-based resin to manufacture a film including a polyamide-based resin layer and a polyester-based resin layer (step S180). The film manufactured in this manner includes recycled raw materials of the polyamide-based resin recovered from the film 10 including the polyamide-based resin, and virgin raw materials of the polyamide-based resin. The film also includes recycled raw materials of the polyester-based resin recovered from the film 10, and virgin raw materials of the polyester-based resin.

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

[0040] [4. Modifications] Although the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

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

[0042] <4-2> In the above embodiment, the recycled raw materials of each of the polyamide-based resin layer 101 and the polyester-based resin layer 100 are reused in the production of the film. However, the recycled raw materials of each of the polyamide-based resin layer 101 and the polyester-based resin layer 100 do not have to be reused in the production of the film. At least, it is sufficient that the recycled raw materials of the polyamide-based resin layer 101 are reused in the production of the film.

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

[0044] <4-4> In the above embodiment, the melting and cleaning are performed in a common furnace (the filtration device 200). However, the melting and cleaning may be performed in separate furnaces. [Explanation of symbols]

[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 filtration device, 202, 212 filter, 204 dissolving solution, 206 pure water, 208, 218 valve.

Claims

1. A step of dissolving a film containing a polyamide-based resin and a polyester-based resin or an olefin-based resin in a solvent, and filtering the mixture containing the dissolved polyamide-based resin to recover a recycled raw material of the polyamide-based resin and a recycled raw material of the polyester-based resin or the olefin-based resin; A step of producing 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; Including, The method for producing a film, wherein in the step of filtering the mixture, a temperature of the mixture is approximately the same as a temperature of the dissolving solution when the polyamide-based resin contained in the film is dissolved.

2. A method for producing a film as described in claim 1, wherein the dissolving liquid contains ethylene glycol.

3. The method for producing a film according to claim 2 , wherein the temperature of the dissolving solution when dissolving the polyamide resin contained in the film is 170° C. or more and 190° C. or less.

4. Measuring the viscosity of the recycled raw material of the polyamide-based resin; The method for producing a film according to claim 1 , further comprising the step of determining a mixing ratio of the recycled raw material of the polyamide-based resin and the virgin raw material of the polyamide-based resin based on the viscosity.

5. 5. The method for producing a film according to claim 1, wherein in the film raw material, the weight of the recycled raw material of the polyamide-based resin is 30 parts or less when the weight of the virgin raw material of the polyamide-based resin is 100 parts.

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