JP5498144B2 - Collection method of carbon fiber - Google Patents

Description

  The present invention relates to a carbon fiber recovery method. More specifically, the present invention relates to a carbon fiber recovery method capable of recovering carbon fiber by removing plastic in a carbon fiber reinforced plastic (hereinafter also simply referred to as “CFRP”).

  Conventionally, superheated steam has been used for drying large ceramic molded bodies, powder processing, mold surface modification, hydrogen production equipment, food processing (heating, drying, thawing, baking, steaming, sterilization, sterilization, deodorization, etc.), etc. Widely deployed in the field. In recent years, as disclosed in Patent Documents 1 to 3 below, attempts have been made to use superheated steam for recycling. Moreover, the following patent document 4 is known as a superheated steam generator.

JP 2004-189848 A JP 2007-071452 A JP 2006-326383 A JP 2008-201625 A

  Patent Document 1 relates to a carbonization processing method and a carbonization processing system. This Patent Document 1 describes that carbon fiber-reinforced plastic (FRP) can be carbonized and separated into activated carbon and fiber (glass) by using a separating device such as a vibration mill together. However, since this apparatus and system are intended for carbonization, the resin component is carbonized, and there is a problem that it is necessary to remove the remaining carbide. Furthermore, no consideration has been given to recovering carbon fiber from CFRP in a reusable form.

  Patent Document 2 relates to a high-temperature steam generator. In this Patent Document 2, there is a description that when superheated steam is irradiated on the FRP crushed material, the resin component is vaporized and glass fiber remains as a residue. However, there is no general description, and no investigation has been made on a method for recovering glass fibers while suppressing the carbonization of the resin content of the FRP crushed material using this device. No attempt has been made to recover carbon fiber from CFRP in a possible form.

  Further, Patent Document 3 relates to a method for recycling a scrap car. Although this patent document 3 describes that most resins such as polyethylene and polypropylene are thermally decomposed and vaporized by heating with superheated steam up to 550 ° C., they remain without being thermally decomposed. There is a description that thermosetting resins and FRP-based resins eventually remain as carbides. However, as described above, since the thermosetting resin is carbonized as described above, it becomes a problem that it is necessary to remove the remaining carbide. Furthermore, no consideration has been given to recovering carbon fiber from CFRP in a reusable form.

  An object of the present invention is to provide a method for recovering carbon fibers that allows carbon fibers to be extracted from carbon fiber reinforced plastics in a reusable manner. In particular, an object of the present invention is to provide a carbon fiber recovery method capable of recovering carbon fiber by suppressing carbonization of the plastic constituting the carbon fiber reinforced plastic when the carbon fiber reinforced plastic is subjected to superheated steam treatment.

The present invention is shown below.
<1> An object to be treated including carbon fiber reinforced plastic provided with a laminated carbon fiber base fabric formed by laminating carbon fiber base fabrics formed by bundles of carbon fibers is treated with superheated steam at 800 ° C. or higher. By removing the plastic in the carbon fiber reinforced plastic, the carbon fiber is recovered while maintaining the fiber bundle while peeling the base fabric layer of the laminated carbon fiber base fabric Fiber recovery method.
<2> When the plastic contained in the carbon fiber reinforced plastic before the treatment is 100% by mass, the treatment removes 68 to 80% by mass of the plastic and leaves 20 to 32% by mass. <1> The method for recovering a carbon fiber according to <1>.
<3> The carbon fiber recovery method according to < 1 > or < 2 >, wherein the treatment is performed under normal pressure.
<3> an introduction part for introducing water vapor;
A heater unit that heats the water vapor to 800 ° C. or higher to form superheated water vapor;
A holding unit for holding the object to be processed;
A discharge part for discharging the superheated steam, and in order from the upstream side to the downstream side of the steam,
The heater unit includes a heating element, a container in which the heating element is housed, and an excitation coil that is wound around the outside of the container.
Carbon fiber in any one of said <1> thru | or <3> performed using the collection | recovery apparatus of the carbon fiber which the said heat generating body becomes from the electromagnetic induction type heat generating body molding material represented by following General formula (1). Recovery method.
La _1-x M ¹ _x M ² O _3-y (1)
[Wherein, M ¹ is at least one element selected from Mg, Ca, Sr and Ba, M ² is at least one element selected from Cr, Co and Mn, and 0 < x ≦ 0.5 and 0 ≦ y ≦ 0.1. ]

According to the carbon fiber recovery device, the carbon fiber can be extracted from the carbon fiber reinforced plastic in a reusable manner. In particular, when the carbon fiber reinforced plastic is subjected to the superheated steam treatment, the carbon fiber can be recovered by suppressing carbonization of the plastic constituting the carbon fiber reinforced plastic.
In the case of providing a fiber bundle in which carbon fibers are bundled and removing 68 to 80% by mass of the plastic in the above treatment and leaving 20 to 32% by mass, and collecting the carbon fiber in a state of maintaining the form of the fiber bundle, In particular, carbon fibers excellent in reusability can be recovered. In particular, even a long carbon fiber can be collected in a short time without impairing its form.
According to the carbon fiber recovery method of the present invention, the carbon fiber can be extracted from the carbon fiber reinforced plastic in a reusable manner. In particular, when the carbon fiber reinforced plastic is subjected to the superheated steam treatment, the carbon fiber can be recovered by suppressing carbonization of the plastic constituting the carbon fiber reinforced plastic.
In the case of providing a fiber bundle in which carbon fibers are bundled and removing 68 to 80% by mass of the plastic in the above treatment and leaving 20 to 32% by mass, and collecting the carbon fiber in a state of maintaining the form of the fiber bundle, In particular, carbon fibers excellent in reusability can be recovered. In particular, even a long carbon fiber can be collected in a short time without impairing its form.

It is typical sectional drawing which shows an example of the collection | recovery apparatus of carbon fiber. It is typical sectional drawing which shows the other example of the collection | recovery apparatus of carbon fiber. It is typical sectional drawing which shows the other example of the collection | recovery apparatus of carbon fiber. It is a typical perspective view which shows an example of the structure of a heat generating body. It is a typical perspective view which shows the other example of the structure of a heat generating body. It is a typical perspective view which shows an example of an integrated heat generating body. FIG. 7 is a schematic plan view of the assembled heating element shown in FIG. 6. It is a typical perspective view which shows the other example of an assembly heat generating body. It is a typical perspective view which shows the further another example of a laminated heat generating body. It is a typical perspective view which shows an example of the form of a holding | maintenance part. It is a typical perspective view which shows the other example of the form of a holding | maintenance part.

Hereinafter, the present invention will be described in detail with reference to FIGS.
[1] Carbon Fiber Recovery Device A carbon fiber recovery device 10 (hereinafter, also simply referred to as “device 10”) used in the present invention includes an introduction part 11a for introducing water vapor,
A heater unit 12 for heating the water vapor to 800 ° C. or higher to form superheated water vapor;
A carbon fiber recovery device comprising: a holding unit 13 that holds a target object including carbon fiber reinforced plastic;
By treating the object to be treated with the superheated steam, the plastic in the carbon fiber reinforced plastic is removed and the carbon fiber is recovered.

  The positional relationship among the introduction part 11a, the heater part 12 and the holding part 13 is not particularly limited, but usually, the introduction part 11a, the heater part, and the holding part 13 are arranged in this order from the low water vapor temperature side. That is, the introduction part 11a, the heater part, and the holding part 13 are arranged in this order from the upstream side to the downstream side of the water vapor. These parts may be adjacent to each other, but other parts may be interposed. Each part will be described below.

  The “introducing section (11a)” is for introducing water vapor. The shape and size of the introduction part are not particularly limited. The water vapor here is usually saturated water vapor, but superheated water vapor of less than 800 ° C. may be introduced.

  The “heater part (12)” heats the steam introduced from the introduction part 11a to superheated steam at 800 ° C. or higher. The structure of this heater part is not specifically limited, For example, the heater part which employ | adopted various systems, such as an electromagnetic induction system and a pressurization heating system, is mentioned. These may be used alone or in combination of two or more. Among these, the heater unit 12 employing an electromagnetic induction method is preferable.

As the heater part 12 which employ | adopted the electromagnetic induction system, FIG.1 and FIG.2 is illustrated. The heater unit 12 (that is, the electromagnetic induction heater unit 12) includes, for example, a heating element 121, a container 124 in which the heating element 121 is accommodated, and an exciting coil that is wound around the outer side of the container 124. 125.
Among them, the heating element 121 is heated by electromagnetic induction with energization of the exciting coil 125. The heating element 121 can generate heat up to a high temperature of about 900 ° C. without being decomposed, altered, degassed, deformed grain growth or the like by electromagnetic induction.
The accommodating portion 124 is a container that accommodates the heating element 121 while being interposed between the heating element 121 and the exciting coil 125.
Furthermore, the container 124 also functions as a flow path for preventing the water vapor and superheated water vapor from being opened to the outside. The exciting coil 125 is a coil for causing the heating element 121 to generate heat by electromagnetic induction.

The material for forming the heating element 121 is not particularly limited as long as it is a material that generates heat by electromagnetic induction. However, in the carbon fiber recovery device 10 of the present invention, the following electromagnetic induction heating element molding material (hereinafter simply referred to as “molding”). Material)). As the molding material, for example, a compound represented by the following general formula (1) (hereinafter also referred to as “specific oxide”) is preferable.
La _1-x M ¹ _x M ² O _3-y (1)
[Wherein, M ¹ is at least one element selected from Mg, Ca, Sr and Ba, M ² is at least one element selected from Cr, Co and Mn, and 0 < x ≦ 0.5 and 0 ≦ y ≦ 0.1. ]

In this specific oxide, the element M ¹ is at least one selected from Mg, Ca, Sr and Ba, and may be only one of these, or a combination of two or more. Good. In the present invention, the element M ¹ preferably contains Sr, and the specific oxide in this case can be represented by the following general formulas (3) and (4).
La _1-x Sr _x M ² O _3-y (3)
La _1-x Sr _xz M ¹¹ _x-xz M ² O _3-y (4)
[However, M ¹¹ is at least one element selected from Mg, Ca, and Ba, and M ² is at least one element selected from Cr, Co, and Mn, and 0 <x ≦ 0. 0.5, 0 ≦ y ≦ 0.1, and 0.5 ≦ z <1. ]
The specific oxides represented by the general formulas (3) and (4) may be used alone or in combination.

Similarly, the general formula (1), (3) and (4) the specific oxide represented by the element ^{M 2} is at least one selected Cr, Co and Mn, 1 of these It may be a seed alone or a combination of two or more. In the present invention, the element M ² preferably contains Mn.

  In the specific oxides represented by the above general formulas (1), (3), and (4), 0 <x ≦ 0 from the viewpoint of stability when heat is generated by electromagnetic induction (particularly heat generated at 800 ° C. or more). .5. Further, from the viewpoint of long-term use and repeated use, it is preferably 0 <x ≦ 0.4, more preferably 0.1 ≦ x ≦ 0.3.

In the present invention, the specific oxide is a compound in which the element M ¹ is Sr in the general formula (1), that is, a compound represented by the general formula (3), and the element M ² is Mn. And preferably a compound satisfying 0.1 ≦ x ≦ 0.3. When the molding material contains this compound, it is easy to generate heat to a desired temperature in a high temperature range of 800 ° C. or higher due to electromagnetic induction, and is particularly excellent in corrosion resistance when generating superheated steam at this temperature.
In addition to the specific oxide, the molding material may contain inevitable impurities generated during the production of the specific oxide and an oxide represented by the following general formula (5).
LaM ² O _3-y (5)
[Wherein M ² is at least one element selected from Cr, Co and Mn, and 0 ≦ y ≦ 0.1. ]

  The content ratio of the specific oxide contained in the molding material is preferably 80% by mass or more, more preferably 95 to 100% by mass, when the total of all the compounds is 100% by mass. The higher the content ratio of this specific oxide, the better the stability to a high exothermic temperature of 800 ° C. or higher.

Furthermore, the heating element made of this molding material can be provided with a coating portion disposed on the surface thereof and containing a compound represented by the following general formula (2) (when this coating portion is provided, A portion made of a specific oxide is called a base). This covering part may consist of only one layer or may consist of two or more layers.
La ₂ O ₃ · n (SiO ₂ ) (2)
[In the formula, n is a number of 1 or more and 2 or less. ]

  The said coating | coated part is a part (layer) which covers the surface of the said base, and contains the compound represented by the said General formula (2). That is, the covering portion may be a portion composed only of the compound represented by the general formula (2), or a portion composed of the compound represented by the general formula (2) and another compound. Also good. The content of the compound represented by the general formula (2) is preferably 40% by mass or more, more preferably 50% by mass, with respect to the total amount of the compounds constituting the covering portion, from the viewpoint of durability of the heating element. As mentioned above, More preferably, it is 60 mass% or more, Most preferably, it is 65-100 mass%.

The compound represented by the general formula (2) contained in the covering portion may be only one type or two or more types. In the general formula (2), compounds in the case of n = 1 and n = 2, that is, La ₂ O ₃ .SiO ₂ and La ₂ O ₃ .2SiO ₂ are stable compounds. Further, in the case of a compound of 1 <n <2, when the molding material having this configuration is used as a heating element by using electromagnetic induction, it tends to change to a compound of n = 1 and / or n = 2 with time. .
The structure of the compound represented by the general formula (2) constituting the covering portion is identified (qualitative analysis) by X-ray diffraction.

In addition to the compound represented by the general formula (2), for example, the covering portion may include another compound represented by the following general formula (6).
p (M ² O) · q (SiO ₂ ) (6)
[Wherein, M ² O is one or more of oxides of at least one element M ² selected from Cr, Co, and Mn, and 0 ≦ p / q ≦ 10. ]
The structure of the general formula (6) is identified (qualitative analysis) by X-ray diffraction.

In the heat generating element used in the present invention, the element M ² constituting the compound represented by the general formula (6) the particular oxide contained in said base (the compound represented by the general formula (1)) preferably contains an element M ² the same elements constituting. For example, when the specific oxide is La _1-x Sr _x MnO ₃ , the element M ² in the general formula (6) representing another compound is preferably Mn. That is, the other compound represented by the general formula (6) includes the following formula (7).
p ¹ (MnO) · p ² (Mn ₂ O ₃ ) · q (SiO ₂ ) (7)
In the general formula (7), when p ¹ = 1, preferably 0 ≦ p ² ≦ 3 and 0.5 ≦ q ≦ 1.

The thickness of the covering portion is preferably 0.5 to 50 μm from the viewpoint of stability as a heating element using electromagnetic induction, reducing the influence of the difference in thermal expansion coefficient between the heating element itself and the covering portion, and the like. More preferably, it is 1-10 micrometers, More preferably, it is 2-5 micrometers.
The method for forming the covering portion is not particularly limited, and examples thereof include a method using polysilazane described later, a sol-gel method, a thermal spraying method, and the like. Among these, the method using polysilazane includes a molded body preparation step for obtaining a molded body containing the compound represented by the general formula (1) and a polysilazane on the surface of the molded body using a solution containing polysilazane. A coating film forming step for forming a coating film, and a film forming step for heat-treating the coating film to form a film containing the compound represented by the general formula (2).

  The said molded object preparation process is a process of obtaining the molded object containing the said specific oxide. In this step, a raw material composition containing a powder made of a specific oxide (which may contain a molding binder, a sintering aid, etc.) is subjected to press molding such as a die press, CIP, etc., and has a predetermined shape. (Rod, wire, plate, sphere, polyhedron, etc.), and this is heat-treated at a temperature of, for example, 1,200 ° C. to 1,600 ° C. in an oxygen-containing atmosphere such as air or a vacuum atmosphere. By this, it can be set as a molded object.

〔式中、Ｒ^１、Ｒ^２及びＲ^３は、互いに同一又は異なって、水素原子、アルキル基、アルケニル基、シクロアルキル基、アリール基、フルオロアルキル基、アルキルアミノ基又はアルキルシリル基である。〕 In the coating film forming step, a coating film containing polysilazane is formed on the surface of the molded body using a solution containing polysilazane (hereinafter referred to as “polysilazane solution”).
The polysilazane includes a unit represented by the following general formula (8), and the number average molecular weight is preferably 30,000 to 120,000, more preferably 32,000 to 80,000, and still more preferably 36,000. ~ 54,000 compounds.

[Wherein, R ¹ , R ² and R ³ are the same or different from each other, and each represents a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, a fluoroalkyl group, an alkylamino group or an alkylsilyl group. ]

The solvent in the polysilazane solution is preferably a compound that dissolves polysilazane, and examples thereof include toluene, xylene, mesitylene, 2-butanone, methyl isobutyl ketone, and propylene glycol monomethyl ether acetate. These may be used alone or in combination of two or more.
The concentration of polysilazane in the polysilazane solution is not particularly limited.
A commercial item can be used for the said polysilazane solution, for example, the polysilazane solution "NN310-30" (brand name) by AZ Electronic Materials can be used.
In the coating film forming step, the method for forming the coating film is not particularly limited, and a dipping method, a spray method, a spin coating method, or the like is applied. Moreover, the temperature at the time of coating film formation is not specifically limited, either, Room temperature etc. can be used.

  Next, in the film forming step, the coating film on the surface of the molded body is heat-treated to form a film containing the compound represented by the general formula (2). In this step, polysilazane is decomposed by reaction with itself or with water to form a Si—O—Si network, and at the same time, the Si element and the general formula (1) constituting the molded body are formed. ), A compound oxide composed of La element, that is, a compound represented by the general formula (2) is formed. Depending on the type of the compound represented by the general formula (1), the compound represented by the general formula (6) may coexist in the film (coating portion).

  In the film forming step, the heat treatment condition is that the temperature is preferably in the range of 900 ° C. to 1,500 ° C., more preferably in the range of 1,100 ° C. to 1,300 ° C., and the atmosphere is oxygen such as air. A containing atmosphere is preferred. The above temperature may be combined with temperature rise, temperature maintenance, temperature drop, and the like. The heat treatment time is appropriately selected depending on the size of the molded body, the thickness of the coating film, and the like.

  Each of the coating film forming step and the film forming step may be performed a plurality of times. In this case, although the film part in the obtained molding material contains the compound represented by the general formula (2), when the element distribution of the film part is examined in the cross-sectional direction, it may have an inclined structure.

The shape of the heating element 121 is not particularly limited, and may be a regular shape or an irregular shape. Furthermore, it may be porous. Although the form is not particularly limited, for example, as illustrated in FIG. 4 and FIG. 5, it may be a form provided with a through-hole 122 c that is regularly penetrated.
That is, the heating element 122a illustrated in FIG. 4 is an example of a heating element having a circular cross-sectional shape and a plurality of through holes 122c that can be vertically ventilated and arranged at equal intervals. . Note that a cutout having a semicircular cross-sectional shape in the vertical direction is provided on the side surface (front side in FIG. 4) of the heating element 122a in FIG. 4 in order to improve ventilation. A thing similar to FIG. 4 can also be set as the heat generating body provided with one or more helical communicating holes.
Further, the heating element 122b of FIG. 5 has a plurality of through-holes 122c each having a square shape with the same opening shape, and has a three-dimensional mesh (three-dimensional square lattice) structure that allows ventilation in the vertical and horizontal directions. It is an example of a heat generating body. As similar to FIG. 5, a heating element having a three-dimensional hexagonal lattice structure may be used.

  When the through-hole 122c is provided, the cross-sectional shape, hole diameter, length, number, direction, and the like of the through-hole 122c are not particularly limited as long as the through-hole 122c is ventilated from one surface to the other surface of the heating element (122a, 122b). . The cross-sectional shape may be a circle, an ellipse, a polygon such as a triangle or a rectangle, a star, or the like. Regarding the hole diameter, the shortest length when the cut surface of the hole is obtained is usually 100 μm or more. Further, the through hole 122c may have a uniform hole diameter or may be different from one surface to the other surface. Further, the through hole 122c may be linear or curved from one surface to the other surface. Further, when the heating element includes a plurality of through holes 122c, the cross-sectional shape, hole diameter, length, orientation, interval between adjacent through holes, and the like may be uniform or different. The surface of the wall surrounding the through hole 122c may be provided with a convex portion, a concave portion, or the like for the purpose of increasing the specific surface area.

  The preferable shape of these heating elements 121 (including 122a, 122b, 123a to 123f) is not particularly limited, but is a plate (including a disk and a square plate), a rod, a sphere (including an elliptic sphere), and a linear body. A regular shape such as a polyhedron is preferable. Furthermore, rods, plates, spheres and polyhedrons are more preferable. In addition, the heat generating body 121 may have parts, such as a convex part, a recessed part, and a through-hole.

Furthermore, as illustrated in FIGS. 6 to 9, the heating element 121 can also be used as a combined heating element 123 (including 123 a, 123 c, and 123 e) in which a plurality of heating elements are assembled. In this case, the air permeability of the heating element here may or may not be present. That is, the solid heating element 121 can be used.
The assembled heating element 123 is a composite that is formed by stacking a plurality of heating elements and that allows ventilation in the vertical direction. And the assembly | attachment heat generating body 123 forms the continuous body connected by the contact of each heat generating body (123b, 123d, and 123f are included) as a whole. Thereby, the electronic conductivity between heat generating bodies can be maintained, and heat can be generated by electromagnetic induction. In addition, since the space formed by the plurality of heating elements (including 123b, 123d, and 123f) is continuous at least in the vertical direction, the heating of water vapor is efficiently performed.

  The disc-assembled heating element 123a in FIG. 6 has five disc-type heating elements 123b, and forms a regular pentagon when the centers of the respective disc-type heating elements 123b are connected. 123b is a laminate in which the side surfaces of 123b are arranged in contact with each other, and are stacked in a plurality of stages (see FIG. 7) while being shifted upward. The disc assembly heating element 123a in FIG. 6 has a substantially cylindrical shape in which the disc-shaped heating element 123b in each stage is in contact and apparently the center of the cylinder is hollowed out in the vertical direction. The hollowed portion becomes a water vapor flow path. Instead of using the disc-shaped heating element 123b, a polygonal or elliptical plate can be used, and a heating element can be laminated with a predetermined interval as appropriate.

  A rod assembly heating element 123c in FIG. 8 has a wood pile type structure in which rod heating elements (columnar bodies such as prisms) 123d are alternately stacked while being alternately shifted by a half cycle. Depending on the arrangement method of each rod-shaped heating element 123d, the ventilation path (flow path) when viewed from above may be a straight line, a wavy line, or the like.

The spherical assembly heat generating element 123e in FIG. 9 is arranged and stacked so as to form a regular triangle when the spherical heat generating elements 123f are closely packed in the surface direction and the centers of the spherical heat generating elements 123f are connected. Has an opal structure. Without the closest packing, the spherical heating element 123f is formed into a spherical assembly heating element 123e having an opal structure in which the spherical heating elements 123f are stacked directly above to form a square when the centers of the spherical heating elements 123f are connected. You can also. Further, without using a sphere, a polyhedron such as a cube or a rectangular parallelepiped, an assembled heating element 123 formed by stacking heating elements having a shape such as an elliptical sphere, or a surface of a heating element such as a sphere or a cube, a rod, a line, etc. It can also be set as the assembly | attachment heating element 123 etc. which a heating element protrudes further radially.
6 to 9, the heating elements (each piece) used for forming the assembly heating elements 123 do not need to have the same shape and size, but have the same shape. Therefore, a combination of heating elements having different sizes, a combination of different shapes, or the like can be used.

  The assembled heating element 123 shown in FIGS. 6 to 9 constitutes a continuous body in which adjacent heating elements are connected by surface contact, line contact, or point contact, and has a constant structure without any disturbance. For this reason, it is easy to induce the heat_generation | fever by induction heating, uniform radiant heat can be given from this assembled heat generating body 123, and the efficient heating with respect to the water vapor | steam introduced can be advanced.

In the carbon fiber recovery apparatus used in the present invention , each heating element 121 has a substantially constant distance from the inner space of the container 124, preferably from the surface of the heating element 121 to the inner wall of the container 124. It is preferable to be disposed at a position. The relationship between the outer diameter of the heating element 121 and the inner diameter of the container 124 is preferably the former <the latter from the viewpoint of the heating efficiency of the introduced steam.

  The shape of the container 124 is not particularly limited, but can be, for example, a substantially cylindrical shape. When it is this substantially cylindrical shape, it can be normally set as the form which has cross-sectional shapes, such as circular, an ellipse, and a polygon. The container 124 may have a single layer structure, or a multilayer structure made of the same or different materials. Depending on the purpose, application, etc., there may be a concave portion, a convex portion, a groove portion or the like on the inner wall surface, such as blistering, constriction, or bending.

The material constituting the container 124 is not particularly limited as long as it does not generate heat by electromagnetic induction and has fire resistance. Examples of such a material include aluminum titanate (Al ₂ TiO ₅ ), cordierite, alumina, zirconia, and quartz glass. These may use only 1 type and may use 2 or more types together. Among these, aluminum titanate is preferable. That is, it is preferable that the inner wall of the container 124 is made of a material containing Al ₂ TiO ₅ (aluminum titanate, titanium aluminum pentoxide). When having an inner wall comprising an Al ₂ TiO _5, although the content of _Al 2 TiO ₅ is not particularly limited in this inner wall, preferably 70 vol% or more, more preferably 80% by volume or more, more preferably 90% by volume or more ( It may be 100% by volume). By including Al ₂ TiO ₅ , it is stable against high temperatures up to about 900 ° C., so that it has excellent heat resistance, and further has excellent heat insulation, impact resistance, water vapor resistance, etc. be able to.
In the present invention, it is particularly preferable that the container 124 is a single-layer cylindrical body or a multi-layer cylindrical body, the entirety of which is composed only of Al ₂ TiO ₅ .

  The exciting coil 125 is disposed outside the container 124 so as to surround at least the heating element 121 (including the integrated heating element 123). Usually, it is wound in a circular shape or a spiral shape. Further, the exciting coil 125 is connected to a high-frequency AC power source (not shown), emits a magnetic line of force when power is supplied from the power source, and induces heat generation of the heating element 121.

  A cooling means for cooling the coil 14 may be provided around the excitation coil 14 in order to suppress the influence of radiant heat from the housing 12 when the heat generating structure 11 generates heat.

The “holding part (13)” is for holding an object to be processed including carbon fiber reinforced plastic. In this holding unit 13, the object to be processed is held, and the object to be processed is exposed to superheated steam (such as when placed in a channel filled with superheated steam), or superheated steam is applied to the object to be processed. On the other hand, it is irradiated (when superheated steam is injected from the nozzle and applied to the object to be processed).
The structure of the holding portion 13 is not particularly limited, and may be provided integrally with the container 124 or may be provided separately from the container 124. As a case where the container 124 is provided integrally, a case where the holding unit 13 is provided in a part of the container 124 is exemplified (see FIG. 2). On the other hand, a case where the container 124 is provided separately from the container 124 includes a case where the holding unit 13 is provided separately from the container 124 on the discharge unit 11b side of the apparatus 10 (see FIG. 1). The holding unit 13 can include a holding member 131 for holding the object to be processed regardless of the form. The holding member 131 may be arranged at any position in any configuration and in any shape. For example, in the case where the container 124 is provided separately, the configuration illustrated in FIGS. 10 and 11 can be employed.

That is, the form illustrated in FIG. 10 is an example including a holding member 131 in the form of a lattice arranged on the inner side of the discharge part 11b side (see FIG. 2) of the holding part constituting wall (side wall) 132. On the other hand, the form illustrated in FIG. 11 is an example including a holding member 131 in the form of a frame disposed on the inside of the discharge part 11b side (see FIG. 2) of the holding part constituting wall (side wall) 132.
The material constituting the container 124 can be applied as it is to the material constituting the holding member 131 and the material constituting the holding portion constituting wall 132, but may be the same as or different from the container 124. It may be.

The carbon fiber recovery apparatus 10 (including 10a, 10b, and 10c) used in the present invention may have other configurations in addition to the above configuration. Another configuration is a high-frequency AC power supply. The high-frequency AC power supply may be disposed outside the device 10, but can be attached inside the device 10.
Moreover, the water vapor | steam supply apparatus for supplying the water vapor | steam heated within the apparatus 10 can be provided. The water vapor supply device may be arranged outside the device 10, but can be attached inside the device 10. In the case where a water vapor supply device (not shown) is provided, for example, it can be connected to the introduction portion 11a side of the container 124.
In order to supply water vapor {a mixed gas containing at least water vapor (a mixed gas composed of water vapor and air, etc.)} to the inside of the container 124, the water vapor supply device directly or directly to the introduction part 11a of the container 124 A device that is indirectly coupled. The steam supply apparatus includes a steam production means such as a known boiler. The vaporization at this time may be under reduced pressure, normal pressure, or increased pressure.

  In the apparatus 10, predetermined power is supplied to the exciting coil 125 by a high-frequency AC power source, and the heating element 121 in the container 124 is heated at the same time or after being heated, the steam (mixed water vapor-containing mixture) is supplied from the steam supply apparatus. (Including gas such as gas) is supplied from the introduction part 11a side. And the water vapor | steam is overheated by the heater part 12, and becomes superheated water vapor | steam of the desired temperature of the high temperature range of 800 degreeC or more. Thereafter, the superheated steam formed by the heater unit 12 is discharged from the discharge unit 11b through the holding unit 13 to the outside of the system.

More specifically, the saturated steam that is normally used is accommodated in which the heating element 121 is accommodated from a steam supply device (not shown) at a constant speed or a constant pressure from the introduction portion 11a side of the accommodating body 124. Introduced into the body 124. On the other hand, the heating element 121 is heated by induction heating by the exciting coil 14 in advance, and the introduced saturated steam comes into contact with the heating element 121 or ventilates the heating space in the container 124, thereby overheating. Water vapor is formed. Then, this superheated steam is discharged | emitted from the discharge part 11b.
In addition, as an induction overheating condition by the exciting coil 125, it is preferable to supply power by selecting a transmission frequency from a range of 20 kHz to 100 kHz. Within this range, heat generation to a desired temperature (temperature range of 800 ° C. or more) by the heating element 121 can be efficiently advanced.

  In addition, as illustrated in FIG. 3 (an example using the assembled heating element 123), another configuration can be provided. That is, the carbon fiber recovery device 10 c includes an introduction portion 11 a formed by the opening member 148 a and the bracket 141. Furthermore, the heater unit 12 including the integrated heating element 123, the container 124, and the excitation coil 125 is provided. The heater unit 12 includes a heating element support base 144, an assembly heating element 123 assembled on the heating element support base 144, and a cylindrical container 124 disposed so that the inner wall does not contact the assembly heating element 123. And an exciting coil 125 arranged in a spiral shape so as to surround the assembled heating element 123 outside the container 124 and not to contact the outer wall of the container 124. Moreover, the holding part 13 provided integrally with the container 124 is provided on the discharge part 11 b side of the container 124. The holding portion 13 includes a holding member extending from the inner wall of the container 124.

In addition, the device 10c includes brackets 141 and 142 made of a nonmagnetic material (for example, stainless steel) and a nonmagnetic stainless steel bolt 150 for fixing and holding the container 124 at a predetermined position with respect to the exciting coil 125. And a nut 151 is used.
In addition, on the lower side (introduction portion 11a side) of the container 124, the introduction portion connected to and communicated from a water vapor supply device (not shown) for supplying water vapor to the side held by one bracket 141. 11a. On the other hand, on the upper side (the discharge part 11b side) of the container 124, the discharge part 11b is provided on the side held by the other bracket 142.
Further, a sealing material 146 made of a heat insulating material and a heat insulating layer 126 are disposed on the upper and lower end portions and the outer wall surface of the container 124 so as to be in contact with them. Further, an opening member 148a is disposed in the vicinity of the introduction portion 11a and an opening member 148b is disposed in the vicinity of the discharge portion 11b through the sealing material 146 and the heat insulating layer 126, respectively. Each of the opening members 148a and 148b includes tubular portions protruding outward and forming the introduction portion 11a and the discharge portion 11b, respectively, and includes lid portions 149a and 149b for blocking both ends of the heat insulating layer 126.

  The excitation coil 125 is connected and fixed from an appropriate bracket, and is connected to a high-frequency AC power source (not shown) for supplying a voltage of an appropriate frequency to the excitation coil 125. Further, in order to protect the exciting coil 125 from the radiant heat generated from the outer wall of the container 124 when the assembled heating element 123 is heated using the magnetic field change due to the voltage supply to the exciting coil 125, A cooling system (not shown) for supplying cooling water to the inside is provided.

  The container 124 is fixed by brackets 141 and 142, bolts 150, and nuts 151 disposed through appropriate heat insulating materials 147a and 147b. In addition, the brackets 141 and 142 also fix the opening members 148a and 148b, respectively, and form the introduction portion 11a and the discharge portion 11b by the fixed opening members 148a and 148b.

  In addition to the bracket 142, the bolt 150, and the nut 151, the bracket 141 includes a spring coil or the like for supplementing the mechanical strength of the container 124 and the airtightness of the introduced steam and / or generated superheated steam. The elastic body 145 and the base 143 are provided. The elastic body 145 is compressed by the pedestal 143, and the pedestal 143 and the bracket 142 are fixed by using the bolts 150 and the nuts 151, so that reliable airtightness and mechanical strength are secured in the container 124. it can.

  As described above, the assembled heating element 123 accommodated in the accommodating body 124 is formed into an annular shape by five disk-shaped molding materials, and forms a substantially cylindrical body that is laminated while being shifted one step at a time ( (See FIGS. 3, 6 and 7). Accordingly, the inner wall surface of the heat generating assembly 123 that forms a continuous uneven surface by passing the water vapor introduced from the water vapor supply device through the introduction portion 11a through the through hole of the substantially cylindrical heat generating assembly 123. The superheated steam is generated by the assembled heating element 123 that generates heat by electromagnetic induction. The generated superheated steam is then discharged from the discharge part 11b.

[2] Carbon Fiber Recovery Method The carbon fiber recovery method of the present invention (hereinafter also simply referred to as “recovery method”) is a laminated carbon in which a carbon fiber base fabric formed by a fiber bundle in which carbon fibers are bundled is laminated. By treating the object to be treated including carbon fiber reinforced plastic provided with a fiber base fabric with superheated steam at 800 ° C. or higher, the plastic in the carbon fiber reinforced plastic is removed, and the base of the laminated carbon fiber base fabric is obtained. The carbon fiber is collected while maintaining the fiber bundle while peeling the cloth layers .

  According to the recovery method of the present invention in which CFRP is treated with superheated steam having a temperature of 800 ° C. or higher, carbon fibers can be extracted from the carbon fiber reinforced plastic in a reusable manner. That is, the plastic constituting CFRP can be removed while suppressing carbonization. Furthermore, when removed, a portion corresponding to a part of the original plastic mass remains moderately. Thereby, in particular, when a laminated fabric in which a carbon fiber base fabric is laminated in CFRP (laminated carbon fiber base fabric) is included, while maintaining the form of each base fabric while peeling the layers, The carbon fibers can be recovered while suppressing dissociation between the single fibers of the carbon fiber bundle.

The “object to be treated” may be a treated product including a carbon fiber reinforced plastic provided with a laminated carbon fiber base fabric in which carbon fiber base fabrics formed by fiber bundles of carbon fibers are laminated. The form and the like are not particularly limited. That is, for example, a composite of CFRP and resin (a resin different from the plastic contained in CFRP), a composite of CFRP and metal, a composite of CFRP and ceramic, and the like can be given.

  The “carbon fiber reinforced plastic” is a material in which carbon fiber is contained as a reinforcing material inside the plastic. For example, CFRP obtained by laminating a prepreg impregnated with a filament and / or woven fabric with resin and then press-molding and / or autoclave molding or the like is mixed with the CFRP, and a mixture of resin and short fibers is injection-molded ( Furthermore, CFRP obtained by performing a curing treatment) and the like are included.

The form of the carbon fiber contained in the CFRP is not particularly limited, and the carbon fiber (short fiber and / or long fiber) may be irregularly contained in the CFRP, and the carbon fiber (short fiber and / or long fiber). May be included as a non-woven fabric in CFRP, and carbon fibers (short fibers and / or long fibers) may be included as a woven fabric in CFRP, and may be included in other forms. Moreover, in the nonwoven fabric and the woven fabric, they may be included in a single layer, or may be included by being laminated alone or in combination, but in the present invention, carbon formed by a fiber bundle in which carbon fibers are bundled. It is included as a laminated carbon fiber base fabric in which fiber base fabrics are laminated.

  Further, the carbon fiber contained in the CFRP may be a short fiber or a long fiber, but the present method is capable of recovering the carbon fiber while maintaining the fiber bundle. It is preferable that it is a fiber bundle of long fibers that can be effectively obtained, and further, it is preferably included as a woven fabric using the fiber bundle of long fibers. The number of carbon fibers constituting the fiber bundle is not particularly limited, but may be, for example, 1000 to 24000. In order to obtain the effect of this method more effectively, the number of carbon fibers constituting the fiber bundle is preferably 1000 to 12000, more preferably 1000 to 6000, and particularly preferably 1000 to 3000.

  The “carbon fiber” may be any type, but is usually a fiber obtained by carbonizing a fiber produced by spinning organic fiber, coal pitch, petroleum pitch or the like. That is, for example, PAN-based carbon fiber using polyacrylonitrile (PAN) fiber as a raw material, coal pitch, and pitch-based carbon fiber using petroleum pitch as a raw material are included. These carbon fibers may use only 1 type and may use 2 or more types together.

  Furthermore, although the fiber diameter is not specifically limited, For example, it can be set as 5-15 micrometers. In order to obtain the effect of this method more effectively, the fiber diameter is preferably 5 to 12 μm, more preferably 6 to 10 μm, and particularly preferably 6 to 9 μm. Further, the volume ratio of carbon fibers in the carbon fiber reinforced plastic (the whole CFRP is 100 volume%) is not particularly limited, but can be, for example, 30 to 80 volume%. In order to obtain the effect of this method more effectively, the volume ratio is preferably 40 to 60% by volume, more preferably 40 to 55% by volume, and particularly preferably 45 to 50% by volume.

  The “plastic” is a polymer constituting CFRP. Any plastic resin can be used. That is, for example, a thermoplastic resin, a thermosetting resin, or another resin (polymer) may be used. Examples of the thermoplastic resin include methyl methacrylate resin, polyether ether ketone resin, polyphenylene sulfide resin, and the like. These may use only 1 type and may use 2 or more types together. Examples of the thermosetting resin include an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, a cyanate resin, and a polyimide resin. These may use only 1 type and may use 2 or more types together. Among these, thermosetting resins are preferable, and epoxy resins are more preferable.

  The volume ratio of the plastic in the carbon fiber reinforced plastic (the whole CFRP is 100% by volume) is not particularly limited, but can be, for example, 20 to 70% by volume. In order to obtain the effect of this method more effectively, the volume ratio is preferably 40 to 60% by volume, more preferably 40 to 55% by volume, and particularly preferably 45 to 50% by volume.

The “treatment” is to contact with superheated steam. This contact removes the plastic from the CFRP. The term “removal” as used herein means that the plastic is vaporized, sublimated, decomposed and burned out by superheated steam.
The contact between CFRP and superheated steam in the treatment may be performed in any way. That is, for example, CFRP may be exposed in an atmosphere of superheated steam, or superheated steam may be applied to CFRP using a nozzle or the like. Of these, the former is preferred. If it is the former, ie, exposure, scattering of carbon fiber can be suppressed and it is preferable from a viewpoint of the ease of collection | recovery of carbon fiber. Furthermore, it is more preferable to use the carbon fiber recovery device.

Moreover, in the said process, the temperature of superheated steam should just be 800 degreeC or more, Although the temperature is not specifically limited, 800-1000 degreeC is preferable. When the temperature is within this range, the plastic removal rate can be increased while suppressing carbonization of the plastic. This temperature is more preferably 800 to 900 ° C, particularly preferably 850 to 900 ° C.
Further, the treatment time is not particularly limited, but 2 to 10 minutes is preferable. This is because the plastic can be sufficiently removed within the time in this range, and the contribution to the removal of the plastic tends to be low even if the treatment is performed for a longer time. This time is more preferably 3 to 7 minutes, and particularly preferably 3 to 5 minutes.

Furthermore, in this method, the CFRP to be processed includes a fiber bundle in which carbon fibers are bundled . In this case, in the said process, 68-80 mass% of a plastic is removed, 20-32 mass% is made to remain, and carbon fiber can be collect | recovered in the state which maintained the form of the fiber bundle. This makes it possible to collect carbon fibers that are particularly excellent in reusability, and it is possible to collect carbon fibers in a short time without impairing the form of carbon fibers that are particularly long fibers.
The residual does not mean only the residual plastic before processing, but may be in any form. That is, when converted as a mass ratio of the plastic before processing, it means that what is equivalent to 20 to 32 mass% of the mass remains regardless of the remaining form. This remaining material includes plastic itself, plastic carbide, and the like.

When this "removing 68 to 80% by mass of the plastic and leaving 20 to 32% by mass" is converted as the removal rate based on the formula (9) in the examples described later, The plastic corresponding to 68 to 80% is removed and the plastic corresponding to 20 to 32% is left. " Furthermore, when converted as a residual rate based on the following formula (11), the removal rate is 68 to 80% and the residual rate is 20 to 32%.
Residual ratio _{(%) = {M P -} (M 1 -M 2)} / M P × 100 (11)
Mass of CFRP before processing ―――――――――――― ； M ₁
Mass of CFRP (carbon fiber recovered material) after treatment ---; M ₂
Mass of plastic contained in CFRP before processing; _MP
( _MP is calculated using the content and density of the following carbon fiber reinforced plastics)

  The residual ratio is preferably 20 to 32%, more preferably 24 to 32%, and particularly preferably 25 to 31%. That is, the removal rate is preferably 68 to 80%, more preferably 68 to 76%, and particularly preferably 69 to 75%.

  Furthermore, the treatment is preferably performed under normal pressure. Performing under normal pressure means that the treatment is performed in an open system without sealing the holding portion 13 as shown in FIGS. 1, 2, and 3. By performing the treatment under the normal pressure, the carbon fiber can be recovered from CFRP so as to be reusable without impairing the form of the carbon fiber.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. In the following, “part” and “%” are based on mass unless otherwise specified.

<1> Manufacture of a disc-shaped heating element La _0.8 Sr _0.2 MnO ₃ powder manufactured by Daiichi Rare Element Industrial Co., Ltd. is press-molded (pressure: 20 MPa), and then CIP-molded (pressure: 600 MPa). Thus, a disk shape was obtained. Next, the sintered body having a diameter of 24 mm and a thickness of 10 mm was obtained by firing in an oxygen stream at a temperature of 1,500 ° C. for 5 hours.
Thereafter, this sintered body was ultrasonically cleaned with acetone. And after immersing for 10 second in polysilazane solution "NN310-30" (brand name) by AZ Electronic Materials which adjusted the sintered compact to 25 degreeC, this was taken out and the following conditions were carried out in oxygen stream. And heat treated. As a result, a Si-based oxide film was formed on the surface of the sintered body to obtain a disk-type heating element. The polysilazane of the above product is — (SiH ₂ NH) _n —, which is a compound of n = 800 to 1,200.
<Heat treatment conditions>
The coated sintered body was heated to 450 ° C. over 2 hours and held at 450 ° C. for 1 hour. Thereafter, the temperature was raised to 1,200 ° C. over 5 hours, and the temperature was maintained at 1,200 ° C. for 1 hour. Next, the temperature was lowered to room temperature over 5 hours.

The disc-shaped heating element was subjected to XRD measurement using “RINT2000” (model name) manufactured by Rigaku and D-SIMS measurement using “ADEPT1010” (model name) manufactured by PHI, respectively. Composition analysis and depth direction analysis from the coating surface. As a result, it was found that the covering portion was made of La _9.33 Si ₆ O ₂₆ and Mn ₇ SiO ₁₂ . Furthermore, it was determined these _{proportions, La} 9.33 _Si 6 _{O 26} is 65 _wt%, Mn 7 _{SiO 12} was found to be 35 mass%. Furthermore, since the attenuation of the Si element was stagnant around 4 μm from the surface of the disk molding material, it was found that the thickness of the covering portion was about 4 μm.

XRD measurement and D-SIMS measurement are as follows.
<XRD measurement conditions>
X-ray source: Cu
Scan step: 0.02 deg.
Scan speed: 4.0 deg. / Min.
Tube voltage: 40 kV
Tube current: 40 mA
<D-SIMS measurement conditions>
Primary ion: Cs ⁺
Primary acceleration voltage: 5.0 kV
Detection area: 100 μm × 100 μm

<2> Production of carbon fiber recovery device 10 (10b) The disk-shaped heating element obtained in the above <1> is used in units of 5, and each side is brought into close contact with each other to form a regular pentagon. As shown in FIG. 6 and FIG. 7, a disc assembly heating element having a structure in which 50 stages are stacked by shifting by 36 degrees in the vertical direction and the structure can be ventilated in the vertical direction. 123a was obtained. This disk assembly heating element 123 a was used as the assembly heating element 123.
Next, the heating element support base 144 (FIG. 3) is provided so that the assembled heating element 123 does not come into contact with the inner wall of the cylindrical container 124 (inner diameter 69 mm) made of aluminum titanate (Al ₂ TiO ₅ ). (Not shown in FIG. 2 but arranged in the same manner). In addition, a helical excitation coil 125 is disposed outside the container 124 so as to surround the assembled heating element 123 and not to contact the outer wall of the container 124.
Further, a holding unit 13 that is separate from the container 124 was prepared. This holding portion 13 has the form shown in FIG. 10, and a holding portion constituting wall 132 placed on the container 124 and two round bars made of alumina (Al ₂ O ₃ ) are vertically crossed. And holding member 131 that is removably fixed to the inner wall surface of holding portion constituting wall 132 (see FIGS. 2 and 10).

<3> Recovery of carbon fiber Using the apparatus 10b (see FIG. 2) shown in <2> above, the carbon fiber reinforced plastic is treated with superheated steam at each temperature generated in the following manner to recover the carbon fiber. Went. In addition, as a water vapor supply device, a water vapor production boiler and an air supply pump were connected to the introduction part 11a through a pipe.
Then, with the thermocouple placed on the opening of the heating element 123 on the discharge unit 11b side with the holding unit 13 of the device 10b removed, a voltage of 50 kHz is supplied from the high frequency AC power source to the excitation coil 125. The assembled heating element 123 was heated to 1,100 ° C. by electromagnetic induction.

  Thereafter, in Comparative Example 1, saturated steam is supplied from the steam supply device at 9.0 kg / hour, introduced from the introduction portion 11a, and saturated steam is supplied to the outer surface and the inner surface of the heat generating assembly 123 that is generating heat. It was made to contact and it confirmed that the temperature of superheated steam was stabilized at 600 degreeC, and discharged | emitted at 9.0 kg / hour from the discharge part 11b. Next, when the temperature of the superheated steam is stabilized at 600 ° C., the holding part 13 fixed with the CFRP test piece sandwiched between the holding members 131 assembled above and below, while the superheated steam is generated, They were stacked on the container 124 and processed for 3 minutes.

  Similarly, in Examples 1 to 3, the saturated steam is supplied from the steam supply device at 9.0 kg / hour, introduced from the introduction part 11a, and the outer and inner surfaces of the heat generating assembly 123 that generates heat. Saturated water vapor is contacted to generate superheated water vapor at 800 ° C. and discharged from the discharge part 11b at 9.0 kg / hour, and as shown in Table 1, in Example 1, it is 3 minutes, and in Example 2, it is 30 minutes. Each of the treatments was performed for 60 minutes in Example 3 for 60 minutes.

The results of the treatment were evaluated according to the following criteria and are shown in Table 1. That is, Table 1 shows values calculated by the following formula (9), with the mass ratio of the plastic removed from the original carbon fiber reinforced plastic as the removal rate.
In Comparative Example 1 and Example 1, Table 1 shows values calculated by the following equation (10), with the volume of the plastic removed per minute as the removal rate.
Furthermore, the state of the recovered carbon fiber was applied to the following criteria, and the result is shown in the “recovered state” column of Table 1.
“◯”: The base fabric layer was peeled off, and the fiber bundle was maintained and recovered.
“X”: The base fabric layer was not peeled off, and the carbon fiber could not be recovered.

Calculation method removal rate of removal rate _{(%) = (M 1 -M} 2) / M P × 100 (9)
Mass of CFRP before processing ―――――――――――― ； M ₁
Mass of CFRP (carbon fiber recovered material) after treatment ---; M ₂
Mass of plastic contained in CFRP before processing; _MP
( _MP is calculated using the content and density of the following carbon fiber reinforced plastics)

Method of calculating removal rate Removal rate (cm ³ / min) = {(M1-M2) / ρ} / T (10)
Mass of CFRP before processing ―――――――――――― ； M ₁
Mass of CFRP (carbon fiber recovered material) after treatment ---; M ₂
ρ (Plastic density) ―――――――――――; 1.24 g / cm ³
T (processing time) ―――――――――――――――― ； 3 minutes

The carbon fiber reinforced plastic used as a test piece is as follows.
Dimensions: 25mm x 25mm x 2mm
Carbon fiber type; manufactured by Toray Industries, Inc., product name “T300” (fiber diameter 7 μm, density 1.76 g / cm ³ )
Carbon fiber form: Bundles of 3000 single fibers bundled in an untwisted state (width: about 1.5 mm)
Carbon fiber base fabric: Plain woven fabric Carbon fiber lamination number: 10 layers (10-layer laminated carbon fiber base fabric)
Carbon fiber content: 46% by volume (total carbon fiber reinforced plastic 100% by volume)
Plastic type: epoxy resin (density 1.24 g / cm ³ )
Plastic content: 54% by volume (total carbon fiber reinforced plastic 100% by volume)

<4> Effect of Example Although the removal rate in Comparative Example 1 was 65%, the layers of the laminated carbon fiber base fabric were not peeled off, and reusable recovery was not possible.
On the other hand, in Examples 1 to 3, 70% by mass or more of the plastic contained in the carbon fiber reinforced plastic was removed, and the component corresponding to 30% by mass of the initially contained plastic was left. The carbon fiber could be recovered in the state. As a result, the layers of the laminated base fabric made of carbon fiber could be peeled. On the other hand, it was possible to suppress that the fiber bundle was excessively decomposed and dissociated into a single fiber state. From this, it can be seen that the carbon fiber in a state excellent in reusability could be recovered.

  The carbon fiber recovery method of the present invention can be widely used in the field of carbon fiber recycling. For example, it is suitable in various fields that use automobile materials, aircraft materials, sports equipment materials, household electrical appliance materials, and the like.

10, 10a, 10b, 10c; carbon fiber recovery device,
11a; introduction part, 11b; discharge part,
12; heater section,
121: heating element,
122a, 122b: breathable heating element, 122c; vent hole,
123; assembly heating element,
123a; disc assembly heating element, 123b; disc type heating element,
123c; rod assembly heating element, 123d; rod heating element,
123e; sphere assembly heating element, 123f; spherical heating element,
124; container, 125; exciting coil, 126; heat insulation layer,
13; holding part, 131; holding member, 132; holding part constituting wall,
141, 142: bracket, 143: pedestal, 144: heating element support base, 145: elastic body, 146: sealing material, 147a, 147b: heat insulating material, 148a: opening member (opening side opening member), 148b: opening member (Discharge part side opening member), 149a: cover part (introduction part side cover part), 149b: cover part (discharge part side cover part), 150; bolt, 151; nut.

Claims (4)

By treating an object to be treated, which includes a carbon fiber reinforced plastic provided with a laminated carbon fiber base fabric formed by laminating carbon fiber base fabrics formed by bundles of carbon fibers, with superheated steam at 800 ° C. or higher, The carbon fiber-recovered plastic is recovered by removing the plastic in the carbon fiber-reinforced plastic and peeling the base fabric layer of the laminated carbon fiber base fabric while maintaining the fiber bundle. Method.   2. When the plastic contained in the carbon fiber reinforced plastic before the treatment is 100% by mass, the treatment removes 68 to 80% by mass of the plastic and leaves 20 to 32% by mass. Carbon fiber recovery method. The carbon fiber recovery method according to claim 1 or 2 , wherein the treatment is performed under normal pressure. An introduction part for introducing water vapor;
A heater unit that heats the water vapor to 800 ° C. or higher to form superheated water vapor;
A holding unit for holding the object to be processed;
A discharge part for discharging the superheated steam, and in order from the upstream side to the downstream side of the steam,
The heater unit includes a heating element, a container in which the heating element is housed, and an excitation coil that is wound around the outside of the container.
The carbon fiber recovery method according to any one of claims 1 to 3, wherein the heating element is performed using a carbon fiber recovery device made of an electromagnetic induction heating element molding material represented by the following general formula (1). .
La _1-x M ¹ _x M ² O _3-y (1)
[Where M ¹ Is at least one element selected from Mg, Ca, Sr and Ba; ² Is at least one element selected from Cr, Co and Mn, and 0 <x ≦ 0.5 and 0 ≦ y ≦ 0.1. ]

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