Recycling method for fiber-reinforced plastics

Abstract

To recycle fiber-reinforced plastics simply while suppressing damage to the reinforcing fibers themselves.SOLUTION: The recycling method for fiber-reinforced plastics comprises: a cooling step of cooling a fiber-reinforced plastic body to be recycled to become an embrittlement temperature or below; a grinding step of grinding the fiber-reinforced plastic body cooled in the cooling step, with a part or whole area of a portion exposed inside a grinding chamber coated with material containing ceramic, using a grinding device with an outer peripheral speed of grinding blades of 4000 m / min or more; and a separation and recovery step of separating and recovering the ground fragments of the fiber-reinforced plastic body from the grinding step into fiber fragments containing mainly fibers and resin fragments containing mainly resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for recycling fiber-reinforced resins. [Background technology]

[0002] Fiber-reinforced resin materials, such as glass fiber-reinforced resin and carbon fiber-reinforced resin, are lightweight yet strong materials made by dispersing high-strength fiber materials in the resin material. These materials are widely used in automobile parts, aircraft parts, and various machine parts.

[0003] In recent years, the development of recycling technologies for used fiber-reinforced resin materials has been studied. Methods for recovering fibers from fiber-reinforced resin materials mainly include the pyrolysis method (see Patent Document 1), in which the resin components are thermally decomposed and removed by heat treatment to recover reinforcing fibers, and the solvent method (see Patent Document 2), in which the resin components are dissolved and removed using a solvent to recover fibers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 212016 [Patent Document 2] Japanese Patent Application Publication No. 2019-136932 Summary of the Invention [Problem to be solved by the invention]

[0005] In the pyrolysis method, the fiber-reinforced resin material is heated to a relatively high temperature, which may damage the fibers to be recovered. In addition, the resin component is pyrolyzed, so the resin component cannot be recycled.

[0006] Furthermore, the solvent method does not remove resin components efficiently enough, and because chemicals are used, multiple treatments are required, which takes time and effort.Furthermore, this method also decomposes the resin components, so the resin components are not recycled.

[0007] An object of the present disclosure is to provide a method for easily recycling fiber-reinforced resin while suppressing damage to the fibers themselves. [Means for solving the problem]

[0008] The present disclosure includes the following aspects. <1> a cooling step of cooling the fiber reinforced resin body to be recycled to a brittle temperature or lower; a crushing step of crushing the fiber-reinforced resin body cooled in the cooling step using a crushing device in which a part or the whole of a part exposed in a crushing chamber is covered with a material containing ceramic and the peripheral speed of the outer end of the crushing blade is 4000 m / min or more; a separation and recovery step of separating and recovering the pulverized pieces of the fiber-reinforced resin body pulverized in the pulverization step into fiber pieces mainly containing fibrous bodies and resin pieces mainly containing resin; A method for recycling fiber-reinforced resin. <2> The pulverization in the pulverization device in the pulverization step is carried out until the particle size distribution of the pulverized pieces is composed of one continuous group. <1> The method for recycling the fiber reinforced resin according to claim 1. <3> In the pulverization step, a condition of the embrittlement temperature or less is maintained. <1> or <2> The method for recycling the fiber reinforced resin according to claim 1. <4> The cooling temperature in the cooling step is −90° C. or lower. <1> ~ <3> 10. The method for recycling a fiber-reinforced resin according to claim 9, wherein the fiber-reinforced resin is a resin having a molecular weight of 100 or more. <5> The fiber reinforced resin body is formed of a fiber reinforced thermoplastic resin. <1> ~ <4> 10. The method for recycling a fiber-reinforced resin according to claim 9, wherein the fiber-reinforced resin is a resin having a molecular weight of 100 or more. <6> The fiber reinforced resin body is formed of fiber reinforced polypropylene. <1> ~ <5> 10. The method for recycling a fiber-reinforced resin according to claim 9, wherein the fiber-reinforced resin is a resin having a molecular weight of 100 or more. <7> The fiber reinforced resin body is formed of glass fiber reinforced resin. <1> ~ <6> 10. The method for recycling a fiber-reinforced resin according to claim 9, wherein the fiber-reinforced resin is a resin having a molecular weight of 100 or more. <8> In the separation and recovery step, at least one of gravity separation, anti-electrostatic separation, and wind separation is used. <1> ~ <7> 10. The method for recycling a fiber-reinforced resin according to claim 9, wherein the fiber-reinforced resin is a resin having a molecular weight of 100 or more. [Effects of the Invention]

[0009] According to the present disclosure, fiber reinforced resin can be easily recycled while suppressing damage to the fibers themselves. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the steps of a fiber-reinforced resin recycling method according to an embodiment of the present disclosure. [Figure 2] 1 is a block diagram showing a schematic configuration of a grinding system according to an embodiment of the present disclosure. FIG. [Figure 3] FIG. 1 is a flow diagram of the steps performed in the comminution system of an embodiment of the present disclosure. [Figure 4] FIG. 2 is a perspective view of a blade portion and a liner portion of a crusher according to an embodiment of the present disclosure. [Figure 5] 1 is a graph showing the particle size distribution of a fiber reinforced resin body after pulverization. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components are not essential unless otherwise specified.

[0012] When describing embodiments with reference to the drawings in this disclosure, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of components in each drawing are conceptual. Therefore, the front-to-back, left-to-right, and top-to-bottom dimensional ratios of each component and the front-to-back, left-to-right, and top-to-bottom dimensional ratios between components are not limited to the dimensional ratios shown in the drawings.

[0013] Furthermore, unless otherwise specified in the specification, the number of each component element of the present disclosure is not limited to one, and may be present in plural. Note that in the following description of the drawings, similar parts are denoted by similar reference numerals.

[0014] <Fiber reinforced resin body> In the present disclosure, a fiber-reinforced resin body formed from a fiber-reinforced resin material is separated into fiber pieces mainly containing fiber and resin pieces mainly containing resin, and each piece is reused. Examples of fiber-reinforced resin bodies include articles made from glass fiber-reinforced resin or carbon fiber-reinforced resin. Examples include components and parts used in automobiles, aircraft, various machines, sporting goods, etc.

[0015] Examples of the resin in the fiber-reinforced resin material include thermoplastic resins, such as polypropylene, polyethylene, polystyrene, polyamide, acrylic resin, ABS resin, ASA resin, AES resin, and polylactic acid. Examples of the fiber in the fiber-reinforced resin material include glass fiber, carbon fiber, and basalt fiber.

[0016] <Separation procedure> In the present disclosure, as shown in FIG. 1, a fiber reinforced resin body P to be recycled is cooled to below its brittle temperature (cooling process), the fiber reinforced resin body cooled in the cooling process is crushed in a crushing device (crushing process), and the crushed pieces of the fiber reinforced resin body crushed in the crushing process are separated and recovered into fiber pieces mainly containing fiber bodies and resin pieces mainly containing resin (separation and recovery process).

[0017] <Cooling process> In the cooling step, the fiber reinforced resin body P to be recycled is cooled to below its brittle temperature. The brittle temperature here is an index of cold resistance, and is the temperature at which plasticity and ductility decrease, reducing strength against mechanical impact and making the body more susceptible to fracture. The brittle temperature of the fiber reinforced resin body P is the brittle temperature of the resin from which it is made. For example, it is −35°C for polypropylene. In the cooling step, the fiber reinforced resin body P is preferably cooled to a temperature lower than its brittle temperature, and more preferably to −90°C or below. For example, liquefied natural gas, liquefied oxygen, liquefied nitrogen, etc. can be used for cooling.

[0018] <Crushing process> In the pulverization step, the fiber reinforced resin body P cooled to below its brittle temperature is pulverized using the pulverization system 10. The fiber reinforced resin body P cooled to below its brittle temperature is fed into the feed section 12 and pulverized in the pulverizer 20.

[0019] <Crushing system> As shown in Fig. 2, the crushing system 10 used in this embodiment includes an input section 12, a crusher 20, a cyclone section 14, a storage section 16, and a cooling section 18. The input section 12 and the crusher 20 are connected by an input path 13. The crusher 20 and the storage section 16 are connected by a discharge path 15. The storage section 16 and the input section 12 are connected by a circulation path 17. The cyclone section 14 is provided in the discharge path 15.

[0020] The input section 12 has an opening formed therein through which the fiber reinforced resin body P is input, and the fiber reinforced resin body P is sent to the crusher 20 via an input path 13 .

[0021] As shown in FIG. 3, the crusher 20 includes a blade portion 22 and a liner portion 24 in a crushing chamber 20A.

[0022] The blade portion 22 has a disk-shaped base 22A and eight plate-shaped blades 22B arranged at equal intervals in the circumferential direction. The base 22A and the blades 22B are made of stainless steel. The outer periphery of each blade 22B is coated with ceramic, forming a ceramic portion 22BS. In FIG. 3, the ceramic portion 22BS is indicated by gray shading. In this embodiment, the entire outer periphery (end face, plate surface, and plate width surface) of each blade 22B, which corresponds to one-third of the radial length, is coated with ceramic.

[0023] The liner portion 24 is ring-shaped and has teeth 24A formed on its inner periphery. The entire inner periphery of the liner portion 24 (the teeth 24A) is coated with ceramic.

[0024] The blade section 22 is housed inside the liner section 24, and is arranged so that the outer peripheral end face of each blade 22B faces a tooth 24A. The blade section 22 is attached at its disk center to a rotating shaft (not shown), and rotates together with the rotating shaft. The peripheral speed of the outer end of the blade 22B is 4000 m / min or more.

[0025] In the crusher 20, the fiber reinforced resin body P is crushed, and the crushed material is sent to the storage section 16 via the discharge path 15 by the flow generated in the cyclone section 14, and is temporarily stored therein.

[0026] The pulverized material stored in the storage section 16 is either fed again from the feeding section 12 and pulverized in the pulverizer 20, or sent to the next separation and recovery step.

[0027] The cooling unit 18 is connected to a cooling source (not shown), and supplies a refrigerant (cooled air) to the upstream side of the pulverizer 20 so that the cooling path 18A merges with the input path 13. The refrigerant supplied cools the inside of the pulverizer 20. The refrigerant, which has been heated by the pulverization process caused by the operation of the pulverizer 20, returns to the cooling unit 18 via the discharge path 15 on the downstream side of the pulverizer 20 and the return path 18B, where it is cooled again to a predetermined temperature and supplied to the pulverizer 20.

[0028] Because the fiber-reinforced resin body P has been cooled below its brittle temperature, stress is concentrated at the interface between the resin and the fiber due to the difference in linear expansion coefficient between the resin and the fiber, causing the fiber-reinforced resin body P to be crushed at the interface. As a result, the fiber-reinforced resin body P is separated into a fiber piece P1 that mainly contains the fiber body and a resin piece P2 that mainly contains the resin.

[0029] The pulverized fiber reinforced resin body P (fiber pieces P1, resin pieces P2) is sent from discharge path 15 to storage section 16 by the flow generated in cyclone section 14. If the material is to be pulverized again, the fiber pieces P1 and resin pieces P2 in storage section 14 are fed into input section 12. If the material is to proceed to the separation and recovery process, the fiber pieces P1 and resin pieces P2 are removed from storage section 14.

[0030] The decision to re-pulverize the fiber pieces P1 and resin pieces P2 is based on whether the particle size distribution of the fiber-reinforced resin body P introduced for one processing run forms a single continuous group. The particle size distribution depends on the number of blades 22B, the rotation speed, and the number of times the pulverization process is repeated. At the beginning of the pulverization process, as shown in Figure 4(A), the particle size distribution is divided into two groups, large and small. This indicates the presence of large clumps where the fiber and resin are not sufficiently separated. As the pulverization process progresses and the separation of the fiber and resin is achieved to a certain extent, the particle size distribution becomes a single continuous group, as shown in Figure 4(B). Here, "single group" refers to a continuous particle size distribution where the volume zone of the particle size distribution is not divided by two or more peaks. Therefore, the number of pulverization processes required for the pulverizer 20 to be used is confirmed in advance through testing, and the number of pulverization processes is determined and executed.

[0031] In the pulverization process, the coolant from the cooling unit 18 is supplied to the pulverizer 20 through the cooling path 18A, thereby cooling the inside of the pulverizer 20. The temperature of the supplied coolant is equal to or lower than the brittle temperature of the fiber-reinforced resin body P. The coolant, whose temperature has risen due to the operation of the pulverizer 20, returns to the cooling unit 18 through the return path 18B and is cooled again to a predetermined temperature. In this way, the cooling unit 18 can prevent the temperature of the fiber-reinforced resin body P from rising above the brittle temperature.

[0032] The pulverization process is performed using the pulverization system 10 according to the procedure shown in FIG. 5. In step S10, the fiber reinforced resin body P is input into the input section 12. The fiber reinforced resin body P is sent to the pulverizer 20, and in step S12, the pulverization process is performed. The pulverized fiber reinforced resin body P is sent from the pulverizer 20 to the storage section 16 and temporarily stored (step S14). In step S16, it is determined whether the pulverization process has been performed a predetermined number of times, i.e., whether the particle size distribution of the fiber reinforced resin body P is formed into one continuous group. If the determination is negative, the process returns to step S10, and the above process is repeated. If the determination is positive, the pulverization process is terminated, and the process proceeds to the separation and recovery process.

[0033] <Separation and recovery process> In the separation and recovery process, the fiber reinforced resin body P (fiber pieces P1, resin pieces P2) pulverized in the crushing process is separated into the fiber pieces P1 and the resin pieces P2, which are then recovered separately. For example, the fiber pieces P1 and the resin pieces P2 can be separated and recovered separately by a separation method such as gravity separation, antistatic separation, or wind separation.

[0034] <Effects> According to the method for recycling fiber reinforced resin of this embodiment, one or more of the following effects can be obtained. (1) Since the fiber-reinforced resin body P is cooled to below its brittle temperature without being heated to a high temperature, deterioration of the resin itself is suppressed. Furthermore, by concentrating stress at the interface between the fiber and the resin during the cooling process and pulverizing the fiber-reinforced resin body, the fiber-reinforced resin body can be easily separated into fiber pieces P1 and resin pieces P2 without using chemicals.

[0035] (2) Since the blade portion 22 and the liner portion 24 exposed in the grinding chamber 20A are coated with ceramic, it is possible to suppress wear of the blade portion 22 and the liner portion 24 due to collision with the fiber-reinforced resin body P. In this embodiment, only the outer periphery of the blade 22B is coated with ceramic, but the entire blade 22B may be coated with ceramic. Also, in this embodiment, the entire liner portion 24 is coated with ceramic, but only a part of the liner portion 24, for example, a part that protrudes toward the inner periphery, may be coated with ceramic.

[0036] (3) In the pulverizing step, the peripheral speed of the outer end of the blade 22B is set to 4000 m / min or more, which can prevent the fibers and resin from remaining in an unseparated state.

[0037] (4) The pulverization step is carried out until the particle size distribution of the pulverized pieces is constituted by one continuous group, so that it is possible to prevent the fibers and resin from remaining in an unseparated state.

[0038] (5) In the pulverizing step, the interior of the pulverizer 20 is maintained at a temperature equal to or lower than the brittle temperature, so that stress concentration at the interface between the resin and the fibers of the fiber-reinforced resin body P can be maintained. [Example]

[0039] The fiber reinforced resin body was pulverized using the pulverization system 10 under the following conditions to separate it into fiber pieces and resin pieces.

[0040] Fiber-reinforced resin body: Glass fiber-reinforced polypropylene (glass fiber content 30% by mass) Cooling temperature: -90℃ Blade outer edge peripheral speed: 4000 m / min Number of times of grinding: 1 to 4 times The powder obtained in each run was dispersed in water and separated into a floating and a settling portion. The fiber content (w%) was calculated using TG-DTA, and the polypropylene recovery rate was calculated from the polypropylene content in the floating portion, and the fiber recovery rate was calculated from the fiber content in the settling portion.

[0041] The recovery rates of fiber (GF) and polypropylene (PP) for pulverization cycles 1 to 4 are shown in Table 1. As the particle size distribution changes from two peaks to one peak, the recovery rate of polypropylene increases. Furthermore, as the number of pulverization cycles increases, the proportion of the sedimented portion decreases, but the recovery rate of fiber remains approximately constant at 80% to 85%. This is thought to be due to the progress of separation of fiber from polypropylene.

[0042] [Table 1]

[0043] As a comparative example, the peripheral speed of the outer edge of the blade was set to 2000 m / min, and the other conditions were the same as those in the example, and the results are shown in FIG. For pulverizations 1 to 4, the average particle size hardly changed, and the number of peaks did not reach 1. When the outer edge of the blade was moving at a low speed, pulverization did not progress even when the number of pulverization processes was increased. As a result, the recovery rates of both resin and fiber did not increase. [Table 2]

[0044] No visual wear was observed on the blades 22B and the teeth 24A of the liner portion 24 of the crusher 20. When the blades 22B and teeth 24A were not coated with ceramic, wear was observed on the outer corners of the blades 22B and the tips of the teeth 24A. [Explanation of symbols]

[0045] 20A Crushing chamber 22B blade (crushing blade) 24 Liner section P1 Fiber piece P2 resin piece P Fiber reinforced resin body

Claims

1. a cooling step of cooling the fiber reinforced resin body to be recycled to a brittle temperature or lower; a crushing step of crushing the fiber-reinforced resin body cooled in the cooling step using a crushing device in which a part or the whole of a portion exposed in a crushing chamber is covered with a material containing ceramic, and the peripheral speed of the outer end of the crushing blade is 4000 m / min or more; a separation and recovery step of separating and recovering the pulverized pieces of the fiber-reinforced resin body pulverized in the pulverization step into fiber pieces mainly containing fibrous bodies and resin pieces mainly containing resin; A method for recycling fiber-reinforced resin.

2. The pulverization in the pulverization device in the pulverization step is carried out until the particle size distribution of the pulverized pieces is composed of one continuous group. The method for recycling the fiber-reinforced resin according to claim 1.

3. In the pulverization step, a condition of the embrittlement temperature or less is maintained. The method for recycling the fiber-reinforced resin according to claim 1.

4. The cooling temperature in the cooling step is −90° C. or lower. The method for recycling the fiber-reinforced resin according to claim 1.

5. The fiber reinforced resin body is formed of a fiber reinforced thermoplastic resin. The method for recycling the fiber-reinforced resin according to claim 1.

6. The fiber reinforced resin body is formed of fiber reinforced polypropylene. The method for recycling the fiber-reinforced resin according to claim 1.

7. The fiber reinforced resin body is formed of glass fiber reinforced resin. The method for recycling the fiber-reinforced resin according to claim 1.

8. The fiber reinforced resin recycling method according to any one of claims 1 to 7, wherein at least one of gravity separation, antistatic separation, and wind separation is used in the separation and recovery step.

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