Recycling method for optical fiber cable, and manufacturing method for recycled plastic composite material

Abstract

To provide a recycling method for an optical fiber cable, and to provide a manufacturing method for a recycled plastic composite material.SOLUTION: Included is a pulverization step of pulverizing an optical fiber cable or a processed product obtained by removing a support wire from the optical fiber cable to prepare finely pulverized powder whose mean particle diameter is 150 μm or more and 830 μm or less. By forming the finely pulverized powder, it is possible to prevent optical fiber powder from piercing the skin even when touching the finely pulverized powder by hand, and to prevent the optical fiber powder from being precipitated from a surface of a recycled plastic composite material. Further, quality of the recycled plastic composite material can be improved.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recycling optical fiber cables and a method for producing a recycled plastic composite material using optical fiber cables. [Background technology]

[0002] Optical fiber communication is a high-speed, large-capacity communication method. In recent years, optical fiber cables that support optical fiber communication have been widely installed, and the recycling of optical fiber cables, which has low disposal costs and allows for material recycling, has become an issue that contributes to protecting the global environment.

[0003] Optical fiber cables are composed of, for example, optical fibers made of quartz glass, plastic coating materials, and metal materials, and each component material is firmly fixed, so there is a problem that it is difficult to easily separate and recover each component material. For this reason, in the past, they were often recycled as cement materials or thermally recovered as part of thermal recycling.

[0004] In recent years, methods for material recycling of optical fiber cables have also been proposed. For example, Patent Document 1 describes a method for disposing of coated optical fibers in which coated optical fibers, which are optical fibers covered with a plastic coating material, are treated in a supercritical state of water, thereby turning the coating material and the optical fiber into powdered processed materials. The plastic material thus treated can be chemically recycled or thermally recovered, and it has also been proposed that the optical fibers made of quartz glass remaining as residues can be material recycled into quartz glass filters and lenses. However, this method requires high temperature and high pressure conditions, and therefore, even if it is technically possible, it is not profitable, and there is a problem that it is difficult to put into practical use.

[0005] Patent Document 2 describes a method for recycling optical fiber cables, in which the optical fiber cables are exposed to superheated steam generated by a superheated steam generator to overheat and soften them, and then the optical fibers, plastic coating material, and metal materials are manually separated quickly and safely. However, while this method is technically possible, in recent years, optical fiber cables have become increasingly multi-core, with many optical fibers contained in one cable, for the sake of rationalization, and there has been a problem in that manually separating the optical fibers and plastic coating material is inefficient and not profitable. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3219356 [Patent Document 2] JP 2013-223822 A Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, it is possible to incorporate optical fibers into the plastic material recycling process without separating the optical fibers from the plastic material. Originally, plastics containing glass fibers as a filler have been used in a wide variety of applications, such as GFRP (glass fiber reinforced plastic), and are known to have the effect of improving strength.

[0008] However, when the optical fiber cable after removing the metal material is crushed to about 6 mm, which is the performance limit of a normal crusher, and processed into pellets by an extruder, glass wires remain in various places, such as the quantitative feeder of the extruder and in the middle of the extruder mechanism. Since the glass wires are extremely thin, for example, with a thickness of 8 μm to 150 μm, if they adhere to and pierce the skin or mucous membrane, they are difficult to remove, and workers experience itching and pain, making it difficult to continue working. In addition, when the product is molded, the glass wires precipitate on the surface of the recycled plastic composite material and pierce the user's hand. In addition, the tensile elongation of the recycled plastic composite material is low, and the quality is low.

[0009] The present invention has been made in light of the above problems, and has an object to provide a method for recycling optical fiber cables that allows for easy material recycling, and a method for producing recycled plastic composite materials. [Means for solving the problem]

[0010] The optical fiber cable recycling method of the present invention includes a crushing step of crushing the optical fiber cable or a processed product obtained by removing the support wire from the optical fiber cable, to obtain finely pulverized powder having an average particle size of 150 μm or more and 830 μm or less.

[0011] The method for producing a recycled plastic composite material of the present invention produces a recycled plastic composite material using an optical fiber cable as a raw material, and includes a grinding step in which the optical fiber cable or a processed product obtained by removing the support wire from the optical fiber cable is ground into a finely ground powder having an average particle size of 150 μm or more and 830 μm or less. Effect of the Invention

[0012] According to the present invention, the finely pulverized powder has an average particle size of 150 μm to 830 μm, so that the optical fiber powder is prevented from sticking into the hand when the finely pulverized powder is touched, and the optical fiber powder is prevented from precipitating from the surface of the recycled plastic composite material, and the quality of the recycled plastic composite material can be improved. [Brief description of the drawings]

[0013] [Figure 1] 1 is a flow chart showing steps of a method for recycling optical fiber cables and a method for producing recycled plastic composite materials according to one embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view showing an example of a configuration of an optical fiber cable used in an embodiment of the present invention. [Diagram 3] FIG. 1 is a diagram showing a configuration of a fine pulverizing device used in one embodiment of the present invention. [Figure 4] 4 is a diagram illustrating a schematic configuration of a cross section taken along line II shown in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0015] 1 shows steps of a method for recycling optical fiber cables and a method for producing a recycled plastic composite material according to one embodiment of the present invention. The method for producing a recycled plastic composite material according to this embodiment produces a recycled plastic composite material using optical fiber cables as a raw material by the method for recycling optical fiber cables according to this embodiment. Therefore, the method for recycling optical fiber cables and the method for producing a recycled plastic composite material include the same steps, and in this embodiment, the method for producing a recycled plastic composite material will be explained by explaining the method for recycling optical fiber cables.

[0016] 2 shows an example of the configuration of the optical fiber cable 10 used in this embodiment. A representative example of the optical fiber cable 10 used in this embodiment is one having an optical fiber 11 made of quartz glass, an optical fiber coating layer 12 that coats the optical fiber 11, a support wire 13 that suppresses bending or breaking of the optical fiber 11, a support wire coating layer 14 that coats the support wire 13, a protective film 15 that covers the outside of a plurality of core wires, each of which is coated with the optical fiber coating layer 12, and is arranged around the support wire coating layer 14, and an outer sheath 16 that covers the outside of these.

[0017] The optical fiber coating layer 12 is made of, for example, a synthetic resin such as polyethylene (PE) or polyvinyl chloride (PCV). The support wire 13 is made of, for example, a steel material, FRP (fiber reinforced plastic), or aramid fiber depending on the purpose. The support wire coating layer 14 is made of, for example, high density polyethylene (HDPE) and low density polyethylene (LDPE). The protective film 15 is made of, for example, a synthetic resin such as polyamide (PA), and may contain aluminum. The outer jacket 16 is made of, for example, a synthetic resin such as polyethylene. The mass ratio after removing the support wire 13 from the optical fiber cable 10 is, for example, the outer jacket 16 is the most abundant at 80 mass % to 90 mass %, the protective film 15 is about 5 mass %, the optical fiber 11 is about 1 mass % to 10 mass %, and the optical fiber coating layer 12 is about 1 mass % to 10 mass %.

[0018] In this embodiment, the use of the optical fiber cable 10 having such a configuration will be described as an example, but the configuration of the optical fiber cable is not limited to this. Also, the optical fiber cable 10 used in this embodiment may be used waste, scraps or defective products in the manufacturing process, unused products, or a mixture of these.

[0019] In the method for recycling optical fiber cable 10 according to the present embodiment, first, for example, when support wire 13 of optical fiber cable 10 to be processed is made of metal such as steel, it is preferable to remove support wire 13 from optical fiber cable 10 (step S110; support wire removal step). This is because metal such as steel can be recycled as a material, and support wire 13 can be separated relatively easily. Specifically, for example, a peeling machine is used to make cuts with a blade in optical fiber cable 10 and pull while tearing, separating support wire 13 from the other parts.

[0020] If the support wire 13 is made of a material other than metal, there is no need to remove the support wire 13, and it is preferable to proceed to the next step without performing the support wire removal step (step S110).

[0021] Next, for example, the optical fiber cable 10 or the processed product obtained by removing the support wire 13 from the optical fiber cable 10 is pulverized to obtain a finely pulverized powder having an average particle size of 150 μm to 830 μm (step S120; pulverization step). By obtaining a finely pulverized powder having an average particle size of 830 μm or less, the optical fiber powder can be easily handled, the optical fiber powder can be inhibited from precipitating from the surface of the recycled plastic composite material, and the quality of the recycled plastic composite material can be improved. In addition, even if the average particle size is less than 150 μm, the difference in the ease of handling the optical fiber powder and the effect of inhibiting the precipitation of the optical fiber powder from the surface of the recycled plastic composite material is small, and conversely, it becomes difficult to mass-produce the fine powder stably. It is more preferable that the average particle size of the finely pulverized powder is 150 μm to 530 μm, further 150 μm to 350 μm, and further 150 μm to 330 μm.

[0022] The pulverization step (step S120) preferably includes, for example, a primary pulverization step (step S121) in which the optical fiber cable 10 or the processed material obtained by removing the support wire 13 from the optical fiber cable 10 is roughly pulverized to obtain a primary pulverized powder, a secondary pulverization step (step S122) in which the primary pulverized powder is further pulverized to obtain a secondary pulverized powder, a separation step (step S123) in which a predetermined component is separated as necessary, and a tertiary pulverization step (step S124) in which the secondary pulverized powder is finely pulverized to obtain a fine pulverized powder. This is because the pulverization is performed in stages to obtain the desired fine pulverized powder.

[0023] In the primary crushing step (step S121), it is preferable to obtain primary crushed powder of a size that can pass through a mesh with a diameter of 5 cm. In the primary crushing, the long optical fiber cable is crushed into roughly crushed pieces by, for example, a four-axis crusher or a single-axis crusher.

[0024] In the secondary pulverization step (step S122), it is preferable to obtain secondary pulverized powder having an average particle size of, for example, 3 mm to 10 mm. In the secondary pulverization, the material is pulverized into coarse particles using, for example, a single-axis crusher, a double-axis crusher, or a high-speed crusher.

[0025] In the separation step (step S123), for example, when aluminum is used in the protective film 15 of the optical fiber cable 10, it is preferable to separate and extract aluminum powder by gravity separation. This is because aluminum powder can be easily separated by gravity separation and can be recycled as a single material. As a method of gravity separation, for example, separation is performed by stirring in a gravity separation tank using the specific gravity of water.

[0026] In addition, in the separation step (step S123), for example, if polyvinyl chloride is used in the optical fiber coating layer 12 of the optical fiber cable 10, it is preferable to exclude it from the scope of this recycling, or to separate and extract polyvinyl chloride powder by specific gravity separation. If polyvinyl chloride powder is contained, chlorine gas is generated in the extrusion step, and the vinyl chloride is decomposed, resulting in a significant decrease in strength and surface condition. Also, the vinyl chloride is burned, which reduces the strength and color of the recycled plastic composite material. As a method of specific gravity separation, for example, separation is performed by stirring in a specific gravity separation tank using the specific gravity of water.

[0027] In the tertiary pulverization step (step S124), for example, it is preferable to obtain a finely pulverized powder having an average particle size of 150 μm or more and 830 μm or less, further 150 μm or more and 530 μm or less, further 150 μm or more and 350 μm or less, and further 150 μm or more and 330 μm or less. The tertiary pulverization can be performed, for example, by a fine pulverization processing device 100 as described below. Figures 3 and 4 show the configuration of the fine pulverization processing device 100. This fine pulverization processing device 100 includes, for example, a pulverization section 110 that pulverizes the material to be pulverized, a supplying means 120 that supplies the material to be pulverized to the pulverization section 110, a collecting means 130 that collects the material pulverized in the pulverization section 110, a cooling means 140 that cools the pulverization section 110, and a spraying means 150 that sprays water on the material to be pulverized to be supplied to the pulverization section 10.

[0028] The crushing section 110 is configured to crush the material to be crushed by grinding a first grinding member 111 and a second grinding member 112 together. A grinding area having a plurality of projections extending in the radial direction is provided on the outer periphery of the opposing surfaces of the first grinding member 111 and the second grinding member 112. The first grinding member 111 is rotatable by a driving means 113 such as a motor, and the second grinding member 112 is fixed and has a supply port 114 provided in the center. The first grinding member 111 and the second grinding member 112 are housed inside a cover body 115, for example.

[0029] The recovery means 130 is preferably configured, for example, to move the crushed material from the cover body 115 to the temporary storage section 131 by suction, and to separate the crushed material moved to the temporary storage section 131 using a sieve section 132, and to return the crushed material that does not pass through the sieve section 132 to the crushing section 110.

[0030] The cooling means 140 is configured to cool the pulverizing section 110 by, for example, a cooling device 141 that cools compressed air and discharges the cooled air, a nozzle 142 is attached to the tip of the cooling device 141, and compressed air is supplied to the cooling device 141 from a compressor 144 via a pipe 143. The second fitting member 112 and the cover body 115 are provided with a plurality of insertion holes 112A and through holes 115A into which the nozzles 142 of the cooling means 140 are inserted, and the cooling air discharged from the cooling device 141 is blown onto the second fitting member 112 to cool it.

[0031] The spraying means 150, for example, sprays water in a mist form onto the material to be pulverized, thereby increasing the moisture content on the surface of the material to be pulverized, thereby suppressing the temperature rise of the material to be pulverized during fine pulverization. The spraying means 150 is disposed relative to the material supplying means 120, for example.

[0032] In the tertiary pulverization step (step S124), it is preferable to use such a fine pulverization apparatus 100, cool the pulverization section 110 with the cooling means 140, and spray mist-like water onto the material to be pulverized with the spraying means 150. This makes it possible to suppress the temperature rise of the synthetic resin with a low melting point, such as polyethylene, that constitutes the outer sheath 16 of the optical fiber cable 10 and the optical fiber coating layer 12, making it difficult to knead. In addition, in this fine pulverization apparatus 100, the size of the finely pulverized powder can be adjusted, for example, by changing the distance between the first and second grinding members 111 and 112, the size and interval of each protrusion, and the mesh size of the sieve section 132, as necessary.

[0033] After the fine pulverization step (step S120), for example, the finely pulverized powder is heated and melt-kneaded by applying a shear force (step S130; melt-kneading step). For melt-kneading, it is preferable to use a twin-screw extruder or a single-screw extruder. If a twin-screw extruder is used, the material can be further broken down by shear force, so that the multiple materials constituting the optical fiber cable 10 can be thoroughly mixed. A twin-screw extruder, for example, kneads by interlocking two screws, and a single-screw extruder, for example, kneads by using a single screw.

[0034] After the melt-kneading step (step S130), for example, the melt-kneaded processed material is passed through a filter to filter and remove impurities (step S140; impurity removal step). After that, for example, the processed material from which the impurities have been removed is cooled and pelletized to obtain a recycled plastic composite material containing synthetic resin and finely pulverized powder of optical fiber (step S150; pelletization step). The obtained recycled plastic composite material can be processed by injection molding or the like for use.

[0035] As described above, according to the present embodiment, the finely pulverized powder has an average particle size of 150 μm or more and 830 μm or less, so that it is possible to prevent the optical fiber powder from piercing the finely pulverized powder even when touched with a hand, and to prevent the optical fiber powder from precipitating from the surface of the recycled plastic composite material, and also to improve the quality of the recycled plastic composite material. EXAMPLES

[0036] Example 1 First, a waste optical fiber cable 10 shown in Fig. 2 was prepared, and the support wire 13 was separated and removed from the optical fiber cable 10 using a peeling machine (manufactured by Sanritsu Machinery Co., Ltd., CCP type peeling machine) (step S110: support wire removal step). The optical fiber cable 10 used had an optical fiber 11 made of quartz glass, an optical fiber coating layer 12 made of polyethylene, a support wire 13 made of steel, a support wire coating layer 14 made of high density polyethylene and low density polyethylene, a protective film 15 made of polyamide and aluminum, and an outer jacket 16 made of polyethylene.

[0037] Next, the treated material from which the support wire 13 was removed was roughly crushed by a single-axis crusher (manufactured by Changshu Shouyu Machinery Co., Ltd.), and the powder that passed through a mesh with 15 mm holes was used as a primary crushed powder (step S121; primary crushing step). The primary crushed powder was then further crushed by a high-speed crusher (manufactured by Changshu Shouyu Machinery Co., Ltd.), and the powder that passed through a mesh with 6 mm holes was used as a secondary crushed powder (step S122; secondary crushing step). Next, aluminum powder was separated from the secondary crushed powder by gravity separation using a gravity separation tank (manufactured by Jiangsu Xinrong Science & Technology Development Co., Ltd.) and extracted (step S123; separation step).

[0038] Thereafter, the secondary pulverized powder from which the aluminum powder had been removed was pulverized by the above-mentioned fine pulverization processing device 100 to obtain a fine pulverized powder (step S124; tertiary pulverization step). The average particle size of the obtained fine pulverized powder was examined by a sieving method, and it was found that there was a 95% or higher probability that the particle size was within the range of 300 μm ± 30 μm. The sieving method involves preparing multiple sieves with known mesh sizes, passing the particles through in order from the coarsest mesh, measuring the weight of the particles that did not pass through the meshes, and subjecting the particles to statistical processing by fitting the mesh size class values ​​to a normal distribution.

[0039] Next, the obtained finely pulverized powder was melt-kneaded in a twin-screw extruder (step S130; melt-kneading process), filtered to remove impurities (step S140; impurity removal process), and pelletized to obtain pellets of the recycled plastic composite material (step S150; pelletization process).

[0040] Comparative Example 1 Pellets of recycled plastic composite material were obtained in the same manner as in Example 1, except that after primary crushing and passing through a mesh with 15 mm holes, the material was melt-kneaded without secondary or tertiary crushing.

[0041] Comparative Example 2 Pellets of recycled plastic composite material were obtained in the same manner as in Example 1, except that after secondary crushing and passing through a mesh with 6 mm holes, melt kneading was performed without tertiary crushing.

[0042] Comparative Example 3 Pellets of recycled plastic composite material were obtained in the same manner as in Example 1, except that after secondary crushing and passing through a mesh with 3 mm holes, melt kneading was performed without tertiary crushing.

[0043] (evaluation) The obtained recycled plastic composite materials of Example 1 and each Comparative Example were melted and molded to prepare test pieces. As a result, in Comparative Examples 1 to 3, optical fiber powder was precipitated during molding, and residue was observed inside the extruder and the mold. In contrast, in Example 1, no precipitation of optical fiber powder was observed. Furthermore, when the surface state of each test piece was observed, in Comparative Examples 1 to 3, precipitation of optical fiber powder was observed on the surface, and foaming caused roughness on the surface. In contrast, in Example 1, no precipitation of optical fiber powder was observed on the surface, no foaming occurred, and a glossy surface was observed.

[0044] Furthermore, the tensile breaking elongation of each test piece was examined. The tensile breaking elongation was measured according to JIS-K7161. In addition, the tensile breaking elongation of the outer cover 16 (polyethylene) of the optical fiber cable 10 used was also measured as a reference value. The obtained results are shown in Table 1. As shown in Table 1, the tensile breaking depth was lower than the reference value in Comparative Examples 1 to 3, but was significantly higher than the reference value in Example 1.

[0045] [Table 1]

[0046] In other words, according to this embodiment, it is possible to prevent optical fiber powder from piercing the finely pulverized powder when touched with the hand, and it is possible to prevent optical fiber powder from precipitating from the surface of the recycled plastic composite material, and it is also possible to significantly improve the tensile breaking elongation of the recycled plastic composite material.

[0047] Incidentally, pellets and test pieces of the recycled plastic composite material were produced in the same manner as in Example 1, except that the distance between the first grinding member 111 and the second grinding member 112 of the fine grinding processing device 100 and the mesh size of the sieve section 132 were adjusted to produce a finely ground powder with an average particle size of 800 μm ± 30 μm or 500 μm ± 30 μm. As in Example 1, no precipitation of optical fiber powder was observed during molding or in the test pieces, and a surface gloss was observed on the surface of the test pieces.

[0048] Although the present invention has been described above by way of the embodiment and examples, the present invention is not limited to the above embodiment and examples and can be modified in various ways. For example, in the above embodiment, each step is specifically described, but it is not necessary to include all steps, and other steps may be included. [Industrial Applicability]

[0049] It can be used for recycling optical fiber cables and for producing recycled plastic composite materials using optical fiber cables. [Explanation of symbols]

[0050] 10...optical fiber cable, 11...optical fiber, 12...optical fiber coating layer, 13...support wire, 14...support wire coating layer, 15...protective film, 16...outer jacket, 100...fine grinding device, 110... pulverizing section, 111... first mating member, 112... second mating member, 112A... insertion hole, 113... driving means, 114... supply port, 115... cover body, 115A... through hole, 120... supply means, 130... recovery means, 131... temporary storage section, 132... sieve section, 140... cooling means, 141... cooling device, 142... nozzle, 143... piping, 144... compressor, 150... spraying means

Claims

1. A method for recycling optical fiber cables, comprising a crushing step of crushing an optical fiber cable or a processed product obtained by removing a support wire from the optical fiber cable into finely pulverized powder having an average particle size of 150 μm or more and 830 μm or less.

2. The optical fiber cable recycling method according to claim 1, characterized in that in the crushing step, when producing finely pulverized powder, a fine crushing processing device is used that is equipped with a crushing section for crushing the material to be crushed, a cooling means for cooling the crushing section, and a spraying means for spraying water on the material to be crushed and supplied to the crushing section, and the material to be crushed is finely pulverized by spraying water on the material to be crushed and supplied to the crushing section and cooling the crushing section.

3. 2. The method for recycling optical fiber cables according to claim 1, further comprising a melt-kneading step of melting and kneading the finely pulverized powder obtained in the pulverizing step in a twin-screw extruder or a single-screw extruder.

4. A method for producing a recycled plastic composite material using optical fiber cables as a raw material, comprising the steps of: A method for producing a recycled plastic composite material, comprising a grinding step of grinding an optical fiber cable or a processed product obtained by removing the support wire from the optical fiber cable into finely ground powder having an average particle size of 150 μm or more and 830 μm or less.

5. The method for producing a recycled plastic composite material according to claim 4, characterized in that in the pulverization process, when producing finely pulverized powder, a fine pulverization processing device is used that is equipped with a pulverization section for pulverizing the material to be pulverized, a cooling means for cooling the pulverization section, and a spraying means for spraying water on the material to be pulverized and supplied to the pulverization section, and the material to be pulverized is finely pulverized by spraying water on the material to be pulverized and supplied to the pulverization section and cooling the pulverization section.

6. 5. The method for producing a recycled plastic composite material according to claim 4, further comprising a melt-kneading step of melting and kneading the finely pulverized powder obtained in the pulverizing step in a twin-screw extruder or a single-screw extruder.

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