JP6880908B2 - Separate recovery method of carbon fiber reinforced composite material from waste plastic mixture - Google Patents

Description

The present invention relates to a method for separating and recovering a carbon fiber reinforced composite material from a waste plastic mixture.

The carbon fiber is a fiber made by carbonizing acrylic fiber or pitch as a raw material at a high temperature, and is a very fine fiber having a fiber diameter of several μm. A carbon fiber reinforced composite material (hereinafter sometimes referred to as "CFRP") produced by combining this carbon fiber with a thermoplastic resin such as polyethylene, polypropylene or polystyrene or a thermosetting resin such as a phenol resin or an epoxy resin is used. It is widely used in aircraft parts, automobile parts, sporting goods, etc. because it is lightweight but has excellent mechanical properties such as strength and impact resistance. However, CFRP is discarded as waste plastic after use because a recycling route has not been established. Waste plastic may be used as a fuel for firing in a kiln as a substitute waste for thermal energy.

On the other hand, when waste plastic containing CFRP is used as fuel, for example, when it is used as a fuel for firing in a kiln, in an electrostatic precipitator that collects soot in cement kiln firing exhaust gas, the efficiency of collecting soot is improved. There is a problem that causes a drop. This is because the carbon fibers are conductive and flame-retardant, and the carbon fibers entering the electrostatic precipitator cause a decrease in electric charge, which in turn deteriorates the performance of the electrostatic precipitator. by. In order to prevent the charge of the electrostatic precipitator from being reduced by carbon fiber, Patent Document 1 states that when waste plastic containing CFRP is used in a cement manufacturing apparatus, the waste plastic is crushed to a certain particle size or less and cement kiln is used. A technique for supplying to a specific position in the inside has been proposed.

JP-A-2007-131436

In Patent Document 1, it is necessary to pulverize waste plastic containing CFRP to an average particle size of 3 mm or less, but waste plastic not containing CFRP does not need to be pulverized, and excessive pulverization is to be performed. Therefore, if CFRP can be sorted in advance from waste plastics, it is possible to treat only CFRPs individually and treat waste plastics other than CFRP by a normal method, which is efficient from the viewpoint of waste treatment. is there. However, at present, no effective means for selecting carbon fibers has been found.

Therefore, an object of the present invention is to provide a method for efficiently sorting and separately recovering a plastic containing carbon fibers such as CFRP from a waste plastic mixture.

As a result of diligent studies to solve the above problems, the present inventor has performed a step of generating a repulsive force in the carbon fiber reinforced composite material by using electromagnetic induction and selectively discharging only the carbon fiber reinforced composite material. The present invention has been completed by finding a finding that can solve the above-mentioned problems by incorporating the above-mentioned problems.

The present invention comprises a loading and transporting process of loading and transporting a waste plastic mixture containing a carbon fiber reinforced composite material and waste plastic onto a conveyor.
The carbon fiber reinforced composite material in the waste plastic mixture is discharged out of the transport path of the conveyor by an electromagnetic induction action due to the rotation of a magnet installed at a position downstream of the charging position of the waste plastic mixture on the conveyor. Discharge process and
Provided is a recovery step for separately recovering the discharged carbon fiber reinforced composite material and the waste plastic conveyed to the conveyor, and a method for separating and recovering the carbon fiber reinforced composite material from the waste plastic mixture containing the waste plastic mixture. It is a thing.

According to the present invention, the carbon fiber reinforced composite material can be effectively selected from the waste plastic mixture and separated and recovered. In addition, the selected carbon fiber reinforced composite material can be separately crushed and used as a fuel for cement kiln firing or the like. Further, the selected carbon fiber reinforced composite material can be used for recovery and utilization.
Further, according to the present invention, the metallic foreign matter contained in the waste plastic mixture can be sorted and collected at the same time as the carbon fiber reinforced composite material.

FIG. 1 is a schematic view of a sorting device that sorts and sorts and collects carbon fiber reinforced materials and waste plastics. FIG. 2A is a cross-sectional view showing the magnetic pole direction of the magnet, and FIG. 2B is a view showing a region of the magnetic pole in the plan view of the magnet shown in FIG. 2A. FIG. 3 is a schematic view of a sorting device that sorts and sorts and recovers a mixture of carbon fiber reinforced material, waste plastic, magnetic metal, and non-magnetic metal. FIG. 4 is a schematic view showing another embodiment of the sorting device of the embodiment shown in FIGS. 1 and 3.

Hereinafter, the present invention will be described based on its preferred embodiment. In the present invention, the carbon fiber is a fiber made of carbon having a graphite structure, and the carbon content in the fiber is 90% by mass or more. Carbon fibers are generally lightweight, high strength, highly elastic and highly conductive due to this structure. As carbon fibers, for example, fibers made of polyacrylic nitrile (PAN) or fibers made of pitch, which is a by-product of petroleum refining and carbonization, are subjected to flame resistance treatment at 150 to 400 ° C. in the air, and further in the absence of oxygen. It can be obtained by carbonization treatment at 800 to 1500 ° C.

The carbon fiber reinforced composite material (CFRP) to be sorted in the present invention includes carbon fibers and a resin. Examples of the resin contained in CFRP include, but are not limited to, thermoplastic resins such as polyethylene, polypropylene and polystyrene, and thermosetting resins such as phenol resin and epoxy resin. These resins can be used by mixing, melting, welding or impregnating with carbon fibers, or by coating the surface of carbon fibers, and the type and content of carbon fibers and resins to be used can be appropriately selected according to the application of CFRP. ..

Since CFRP has the characteristics of carbon fiber such as light weight and high strength as it is, it is used in various applications such as daily necessities, personal computers, home appliances, automobiles, aircraft, sports equipment, and construction and civil engineering fields. Therefore, plastics containing CFRP are often discharged as general household waste, shredder dust generated in the industrial production process of CFRP, and disposal of automobiles and home appliances, and are discarded as a mixture of plastics with or without CFRP. Ru. Further, the discarded plastic mixture, that is, the waste plastic mixture containing CFRP and waste plastic, may be mixed with foreign substances such as metal and rubber in addition to CFRP due to insufficient separation.

With this, the waste plastic mixture is crushed without completely removing CFRP and mixed foreign substances in the process of intermediate waste treatment for the purpose of weight reduction and resource recovery, and the crushed material is landfilled as final disposal. It was either used or reused as a fuel material. On the other hand, according to the present invention, as described in detail below, CFRP can be selected from the waste plastic mixture, and CFRP and waste plastic can be recovered separately. The method for separating and recovering the carbon fiber reinforced composite material from the waste plastic mixture will be described below with reference to the drawings.

The separate collection method of the present invention is roughly classified into the following steps (a)-(c).
(A) A loading and transporting process in which a waste plastic mixture containing a carbon fiber reinforced composite material and waste plastic is loaded onto a conveyor and transported.
(B) The carbon fiber reinforced composite material in the waste plastic mixture is conveyed to the conveyor by an electromagnetic induction action due to the rotation of a magnet installed at a position downstream of the charging position of the waste plastic mixture on the conveyor. Discharge process to discharge to the outside.
(C) A recovery step of separately recovering the discharged carbon fiber reinforced composite material and the waste plastic conveyed to the conveyor.

The separate collection method of the present invention including the steps (a)-(c) described above can be suitably performed by, for example, the sorting device 1 shown in FIG. The sorting device 1 includes a storage tank 2, a supply device 3, a conveyor 4, a magnet 5, and a separate collection container 6.

<Input process>
The charging step in the present invention is a step of loading and transporting a waste plastic mixture containing a carbon fiber reinforced composite material and waste plastic on a conveyor. In the storage tank 2 shown in FIG. 1, a waste plastic mixture to be sorted is stored regardless of its type, composition, and the like. The waste plastic mixture to be treated in the present invention contains at least CFRP and waste plastic, and may further contain other foreign substances such as metal and rubber. In addition, "waste plastic" refers to "waste plastic not containing CFRP", and is also used in this sense in the following description of "waste plastic".

The shape of the waste plastic mixture to be treated is not particularly limited, and for example, a spherical shape, a flake shape, a plate shape, or a combination thereof can be used. The waste plastic mixture is preferably in a crushed state. Known means can be used as a method for crushing the waste plastic mixture. In the present invention, from the viewpoint of stable supply to the conveyor and ease of sorting CFRP, it is preferable to use one crushed so as to be about 100 mm square or less.

The supply device 3 in the sorting device 1 shown in FIG. 1 is for charging the waste plastic mixture onto the conveyor 4 provided vertically below the supply device 3. The type of the supply device 3 is not particularly limited as long as it can quantitatively adjust the amount of the waste plastic mixture input to the conveyor 4. For example, as the supply device 3, a known fixed-quantity supply device such as a rotary feeder can be used. From the viewpoint of effectively sorting CFRP, it is preferable that the waste plastic mixture is not concentrated in the central portion in the width direction of the conveyor 4 but is dispersed and charged in the width direction of the conveyor 4.

The conveyor 4 in the sorting device 1 shown in FIG. 1 is used to convey the waste plastic mixture charged on the conveyor in one direction. The width and length of the conveyor 4 are not particularly limited and can be appropriately selected depending on the amount of the waste plastic mixture to be treated. The type of conveyor is also not particularly limited, and a roller conveyor, a belt conveyor made of an endless belt, or the like can be used, but from the viewpoint of using the waste plastic mixture for sorting without waste, the conveyor 4 is made of an endless belt as shown in FIG. It is preferable to use the belt conveyor 43. When a belt conveyor is used as the conveyor, the belt of the conveyor 4 is preferably made of a non-magnetic material, for example, a resin. The reason for this is that magnets are used to sort CFRFs from waste plastic mixtures.

As shown in FIG. 1, the belt conveyor 43 is bridged between the drive roll 41 and the driven roll 42, and makes a circumferential motion in the direction indicated by the reference numeral R in the figure. Therefore, the waste plastic mixture charged on the belt conveyor 43 is conveyed in the direction indicated by reference numeral R.

<Discharge process>
In the discharge process, CFRP in the waste plastic mixture is discharged by the electromagnetic induction action due to the rotation of the magnet. For this purpose, the magnet is installed at a position downstream of the charging position of the waste plastic mixture on the conveyor 4. In the embodiment shown in FIG. 1, the magnet 5 is arranged inside the driven roll 42 installed at a position downstream along the transport direction R of the belt conveyor 43. The magnet 5 has a cylindrical shape. The length of the magnet 5 in the longitudinal direction substantially coincides with the width orthogonal to the transport direction R of the belt conveyor. Further, as shown in FIG. 2A, the magnet 5 has S poles and N poles of the magnet alternately arranged in the circumferential direction on the outer peripheral surface of the magnet 5 in a cross section orthogonal to the longitudinal direction of the magnet 5. The magnetic poles are arranged so that they are located. Therefore, when the magnet 5 is viewed in a plan view, as shown in FIG. 2B, S poles and N poles appear alternately as the magnet 5 rotates. As a result, the magnetic poles change continuously just above the magnet 5, and the electromagnetic induction action occurs due to the change.

The magnet 5 may be a permanent magnet or an electromagnet. Permanent magnets and electromagnets may be used in combination. Further, it is preferable that the magnet 5 uses a power device (not shown) different from the drive roll and rotates at a higher speed than the drive roll. In this case, the magnet 5 rotates in the same direction as the moving direction of the belt 43 of the conveyor 4, and the rotation speed is preferably about 1500 rpm to 3000 rpm.

When the waste plastic mixture conveyed by the conveyor 4 is conveyed above the magnet 5, the magnet 5 rotating at high speed causes an electromagnetic induction action on the CFRP to generate an eddy current inside the CFRP. As a result, the CFRP contained in the waste plastic mixture is repelled from the conveyor 4 by the electromagnetic repulsive force (hereinafter, also simply referred to as “repulsive force”) generated in the direction facing the belt 43 surface of the conveyor 4, and is conveyed. It is discharged out of the route. On the other hand, since the waste plastic is not affected by the magnetic force, no repulsive force is generated, the waste plastic remains on the conveyor 43, and the waste plastic freely falls vertically downward from the downstream end of the conveyor.

Generally, carbon fibers are inferior in conductivity to metals, and the fiber diameter of carbon fibers is as small as several μm. Therefore, eddy currents flowing in carbon fibers due to electromagnetic induction action flow in metal. It tends to be smaller than the eddy current. When the eddy current flowing in the carbon fiber is small, the repulsive force acting on the CFRP becomes weak, and as a result, it becomes difficult to discharge the CFRP from the conveyor, and further, it becomes difficult to sort the CFRP from the waste plastic. There is. Therefore, from the viewpoint of more efficiently selecting CFRP, it is preferable to adopt a method of increasing the change of the magnetic field using the rotation of the magnet 5 and strengthening the repulsive force acting on the CFRP. Specifically, (i) a method of using at least one of a permanent magnet and an electromagnet as the magnet 5, (ii) a method of increasing the rotation speed of the magnet 5, or (iii) using a large number of magnets 5 can be used to obtain a magnet. A method of increasing the change in the magnetic field per rotation of the magnet by increasing the number of magnetic poles exposed on the outer peripheral surface can be mentioned. Regardless of which method is adopted, the repulsive force acting on the CFRP can be increased due to the increase in the eddy current generated in the carbon fiber, and the CFRP can be selected more efficiently. In addition, a plurality of these methods can be combined.

Examples of the permanent magnet used in the above method (i) include alnico magnets, ferrite magnets, neodymium magnets, and the like. It is preferable to use a neodymium magnet from the viewpoint of generating a strong repulsive force due to a change in the magnetic field in the CFRP.

In the electromagnet used in (i) above, the electromagnet is provided so that the S pole and the N pole appear alternately in the circumferential direction on the outer peripheral surface of the electromagnet, as in the case of using a magnet such as a permanent magnet. It is preferable to arrange it. In that case, the eddy current generated in the carbon fiber in CFRP can be increased by adopting a method of increasing the frequency of the AC power supply flowing through the electromagnet and / or a method of increasing the voltage flowing through the electromagnet. The resulting strong repulsive force can further improve the sorting efficiency of CFRP.

In (ii) above, from the viewpoint of increasing the sorting efficiency of CFRP, the rotation speed of the magnet is preferably 2000 rpm or more in the same direction as the moving direction of the belt 43 of the conveyor 4, and more preferably 2500 rpm or more. .. In (iii) above, the number of magnets used is preferably such that the change of the magnetic pole in one rotation of the magnet 5 occurs 4 times or more and 8 times or less.

<Recovery process>
In the recovery step, CFRP and waste plastic are separated and recovered from the waste plastic mixture. For this purpose, as shown in FIG. 1, a separate collection container 6 is provided at a position downstream of the downstream end of the conveyor 4 and a position downstream of the downstream end. Since the above-mentioned magnet 5 is provided at a position on the downstream side of the conveyor 4, the CFRP discharged from the belt 43 of the conveyor 4 and the waste plastic remaining on the belt 43 surface of the conveyor 4 are respectively conveyored. It can be collected by the separate collection container 6 provided at the downstream end of 4.

From the viewpoint of ease of reuse, it is preferable to collect CFRP and waste plastic separately. As the separate collection container 6, as shown in FIG. 1, it is preferable to use the CFRP collection container 61 and the waste plastic collection container 62. In this case, it is preferable to arrange the waste plastic collection container 62 at the downstream end of the conveyor 4 and collect the free-falling waste plastic directly into the container 62. On the other hand, the CFRP recovery container 61 is preferably arranged at a position further downstream from the position of the downstream end of the conveyor 4, depending on how the CFRP is blown off by the magnet 5. As a suitable installation position of the CFRP collection container 61, it is advantageous to test the distance at which the CFRP is discharged in advance and install it at a position where it can be appropriately separated and collected.

As described above, according to the separate recovery method of the present invention, even when CFRP is contained in the waste plastic mixture, CFRP can be sorted from the waste plastic mixture and separately recovered. Since the waste plastic does not contain CFRP, it can be used as it is, for example, as a kiln calcined fuel. On the other hand, CFRP can be used as a kiln calcined fuel by performing appropriate pretreatment after separate collection.

Next, another embodiment of the present invention will be described with reference to FIG. It should be noted that the present embodiment mainly describes the points different from the above-described embodiment, and the above-described description of the embodiment is appropriately applied to the same points. Further, in FIG. 3, the same members as those in FIGS. 1 and 2 are designated by the same reference numerals.

Metallic foreign substances may be mixed in the waste plastic mixture in the process of crushing or disposal, which hinders reuse such as incineration of plastic. Therefore, in the present embodiment, when the waste plastic mixture contains a magnetic metal and a non-magnetic metal in addition to the CFRP and the waste plastic, the CFRP, the magnetic metal, and the non-magnetic metal are simultaneously mixed in the discharge step. Discharge.

When a waste plastic mixture containing a magnetic metal is treated, an attractive force of a magnet acts on the magnetic metal, and a repulsive force due to an electromagnetic induction action is generated by a change in a magnetic field due to the rotation of the magnet 5. In this case, the attractive force to the magnet is stronger than the repulsive force caused by the electromagnetic induction action. Therefore, as shown in FIG. 3, the magnetic metal 9 adheres to the belt 43 without being discharged from the belt 43. As it is, it is conveyed to the lower part of the conveyor 4 along the outer circumference of the driven roll 42. Then, as the belt 43 begins to separate from the peripheral surface of the driven roll 42, the magnetic force of the magnet 5 becomes less likely to reach the magnetic metal, the attractive force of the magnetic metal to the magnet 5 becomes smaller, and the magnet 5 freely falls away from the belt 43. ..

On the other hand, when a waste plastic mixture containing a non-magnetic metal is treated, the attractive force of the magnet 5 does not act on the non-magnetic metal, but the non-magnetic metal has conductivity, so that it repels due to the generation of eddy current. Force is generated. Since the non-magnetic metal has better conductivity than CFRP, eddy currents are generated more, and the repulsive force generated in the non-magnetic metal is larger than that of CFRP. Due to this, as shown in FIG. 3, the non-magnetic metal 10 is repelled farther than the CFRP 7 and discharged from the transport path of the conveyor 4.

As described above, in CFRP, waste plastics, magnetic metals and non-magnetic metals, the attractive force of the magnet and the repulsive force generated by the electromagnetic induction action due to the rotation of the magnet are different from each other. The magnetic metal and the non-magnetic metal can be discharged out of the transport path of the conveyor at the same time. The magnetic metal refers to a metal having ferromagnetism, and includes a single metal having ferromagnetism and an alloy with a metal having ferromagnetism. The non-magnetic metal refers to a paramagnetic or anti-magnetic metal, and includes a paramagnetic or anti-magnetic metal alone and an alloy with a paramagnetic or anti-magnetic metal.

In the present embodiment, as shown in FIG. 3, as the separate recovery container 6 of the sorting device 1, in addition to the CFRP recovery container 61 and the plastic recovery container 62, the magnetic metal recovery container 63 and the non-magnetic metal recovery container It is preferable to use 64. The magnetic metal recovery container 63 is preferably installed closer to the drive roll 41 than the plastic recovery container 62, and is located slightly closer to the drive roll 41 than directly below the position where the belt 43 starts to separate from the lower part of the driven roll 42. It is more preferable to install it.

It is preferable that the non-magnetic metal recovery container 64 is installed at a position further downstream from the downstream end of the conveyor 4 than the CFRP recovery container 61. The suitable installation position of the magnetic metal recovery container 63 and the non-magnetic metal recovery container 64 may be such that the distance at which the magnetic metal and the non-magnetic metal are discharged is tested in advance and the container can be appropriately separated and collected. ..

As described above, according to the present embodiment, even when the waste plastic mixture contains CFRP and metals, CFRP, waste plastic, magnetic metal and non-magnetic metal are simultaneously and individually sorted. Can be collected. Since the recovered waste plastic does not contain CFRP, it can be used as it is as a kiln firing fuel. In addition, the recovered CFRP can be used as a kiln calcined fuel by performing appropriate pretreatment. Further, the recovered non-magnetic metal and magnetic metal can be recycled separately.

Although the present invention has been described above based on the preferred embodiment, the present invention is not limited to the above embodiment. For example, in each of the above embodiments, the magnet 5 is installed in the driven roll 42 installed at the downstream end of the conveyor 4, but the installation position of the magnet 5 is not limited to this. For example, as shown in FIG. 4, the conveyor 4 is installed. The magnet 5 may be rotatably arranged at a position downstream of the above, that is, a position closer to the upstream than the installation position of the driven roll 42.

1 Sorting device 2 Storage tank 3 Supply device 4 Conveyor 5 Magnet 6 Sorted recovery container 61 CFRP recovery container 62 Plastic recovery container 63 Magnetic metal recovery container 64 Non-magnetic metal recovery container 7 Carbon fiber reinforced composite material (CFRP)
8 Waste plastic 9 Magnetic metal 10 Non-magnetic metal

Claims (4)

A loading and transporting process in which a waste plastic mixture containing a carbon fiber reinforced composite material and waste plastic is loaded and transported on a conveyor, and
The carbon fiber reinforced composite material in the waste plastic mixture is discharged out of the transport path of the conveyor by an electromagnetic induction action due to the rotation of a magnet installed at a position downstream of the charging position of the waste plastic mixture on the conveyor. Discharge process and
A method for separating and recovering a carbon fiber-reinforced composite material from a waste plastic mixture, which comprises a recovery step of separately recovering the discharged carbon fiber-reinforced composite material and the waste plastic conveyed to the conveyor. The separate collection method according to claim 1, wherein the magnet is at least one of a permanent magnet and an electromagnet. The magnet is designed to rotate along the transport direction of the conveyor.
The separate collection method according to claim 1 or 2, wherein as the magnet, a magnet in which magnetic poles are arranged so that S poles and N poles appear alternately with rotation is used. Further, the waste plastic mixture containing a magnetic metal and a non-magnetic metal is charged onto the conveyor in the charging step.
In the discharge step, the carbon fiber reinforced composite material, the magnetic metal, and the non-magnetic metal are simultaneously discharged.
The method according to any one of claims 1 to 3, wherein in the recovery step, the carbon fiber reinforced composite material, the waste plastic, the magnetic metal, and the non-magnetic metal are recovered separately and simultaneously. Separate collection method.

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