JP5816898B2 - Recycled fiber manufacturing method and recycled fiber manufacturing system - Google Patents

Description

  The present invention relates to a method for producing a recycled fiber and a recycled fiber production, in which the matrix resin is removed and a reusable recycled fiber is obtained while suppressing damage to a fiber part constituting the fiber reinforced resin such as a carbon fiber reinforced resin or a glass fiber reinforced resin. About the system.

  Conventionally, a matrix resin is removed from a fiber reinforced resin that has become a waste material, and a fiber portion is recovered as a reusable recycled fiber. Here, the fiber reinforced resin means a thermosetting resin (for example, unsaturated polyester resin, epoxy resin, phenol resin) or a thermoplastic resin (for example, polypropylene, polyamide resin, It is a composite material whose strength is improved by impregnating various resin components such as methyl methacrylate) as a matrix resin. Examples of the fiber reinforced resin include a carbon fiber reinforced resin in which a bundle of carbon fibers is impregnated with a matrix resin, and a glass fiber reinforced resin in which a bundle of glass fibers is impregnated with a resin component.

  As a method for recovering the fiber portion from the fiber reinforced resin, a method is known in which the matrix resin constituting the fiber reinforced resin is decomposed by exposing the fiber reinforced resin to an atmosphere filled with a supercritical fluid or a subcritical fluid. For example, Patent Document 1 below discloses a method for producing recycled carbon fiber in which a fiber reinforced resin is hydrolyzed while water in a temperature range of 365 to 390 ° C. is supplied into a reaction processing vessel.

JP 2005-336331 A

  However, in the method for producing recycled carbon fiber described in Patent Document 1, water in a temperature range of 365 to 390 ° C. is supplied in a supercritical or subcritical atmosphere in which the fiber reinforced resin is sealed. However, since the decomposition process is performed in the atmosphere in which the supercritical state or the subcritical state is maintained, the energy consumption for maintaining the supercritical state or the subcritical state is increased, and the processing efficiency is low.

  The present invention has been made to address the above problems, and its purpose is recycling that can shorten the supercritical state or subcritical state maintenance time for decomposing the fiber reinforced resin to improve the processing efficiency. An object of the present invention is to provide a fiber manufacturing method and a recycled fiber manufacturing system.

In order to achieve the above object, the present invention is characterized by a resin decomposing solvent used for decomposing a matrix resin constituting a fiber reinforced resin, and a critical fluid heated to a supercritical state or a subcritical state by heating the resin decomposing solvent. A recycled fiber manufacturing method using a critical fluid generating means for generating a fiber and a reaction processing container for containing a fiber reinforced resin and decomposing a matrix resin, the fiber reinforced resin being disposed in the reaction processing container After that, a work placement step for introducing a liquid-state resin decomposition solvent into the reaction processing vessel and immersing the fiber reinforced resin, a work placement step for placing the fiber reinforced resin in the reaction treatment vessel, and a critical fluid generating means A critical fluid generating process for generating a critical fluid in the resin, and a resin decomposing process for decomposing the matrix resin in the fiber reinforced resin disposed in the reaction processing vessel using the critical fluid After the resin decomposition step, and a liquid solvent supply step of lowering the temperature of the reaction process the reaction treatment vessel while discharging the fluid present in the reaction process chamber while introducing resin decomposed solvent in the liquid state into the container There is to include.

  Here, the supercritical state is a state of a fluid in which the resin decomposition solvent is heated to a temperature equal to or higher than the critical temperature of the resin decomposition solvent and is pressurized to a pressure equal to or higher than the critical pressure of the resin decomposition solvent. . The subcritical state is a state of a fluid in which the resin decomposition solvent is heated to a temperature equal to or higher than the critical temperature of the resin decomposition solvent and is pressurized below the critical pressure of the resin decomposition solvent.

According to the feature of the present invention configured as described above, the method for producing recycled fiber includes the step of decomposing a matrix resin in a reaction processing container in which a solvent for resin decomposition is in a supercritical state or a subcritical state, and then in the reaction processing container. The liquid in the reaction processing vessel is discharged while lowering the temperature in the reaction processing vessel by introducing a solvent for resin decomposition in a liquid state. That is, in the method for producing recycled fiber according to the present invention, the matrix resin constituting the fiber reinforced resin is solubilized with a supercritical fluid or a subcritical fluid, and then a resin decomposition solvent in a liquid state is introduced into the reaction processing vessel. As a result, the decomposition product of the solubilized matrix resin is dissolved in the fiber component constituting the fiber reinforced resin or in the reaction processing container while lowering the temperature in the reaction processing container. As a result, in the process of decomposing the fiber reinforced resin, the supercritical state or subcritical state maintenance time can be shortened, and the fiber portion can be efficiently recovered to produce recycled fiber.

Moreover, according to the characteristic of this invention comprised in this way, the manufacturing method of a recycled fiber immerses the fiber reinforced resin arrange | positioned in the reaction processing container in the workpiece | work arrangement | positioning process with the solvent for resin decomposition of a liquid state. Thereby, in the case where a critical fluid is generated by heating the inside of the reaction processing container, carbonization of the matrix resin in the fiber reinforced resin can be prevented and the removal rate and recovery rate of the matrix resin can be improved. In addition, when the matrix resin constituting the fiber reinforced resin is composed of a thermosetting resin, it is possible to improve the removal rate and recovery rate of the matrix resin by preventing curing during heating in the reaction processing vessel. it can.

Another feature of the present invention is that in the method for producing recycled fiber, the critical fluid generating means includes preheated fluid generating means for generating a preheated fluid by preheating the resin decomposition solvent outside the reaction processing vessel. In the resin decomposition step, the preheated fluid generated by the preheated fluid generating means is introduced into the reaction processing vessel, the matrix resin is decomposed while discharging the fluid in the reaction processing vessel, and the liquid solvent is supplied. The step is to obtain the resin-decomposing solvent in the liquid state by lowering the temperature of the preheating fluid introduced into the reaction processing vessel.

According to another feature of the present invention configured as described above, the method for producing recycled fiber includes preheating after decomposing the matrix resin constituting the fiber reinforced resin while introducing the preheating fluid into the reaction processing vessel. By lowering the temperature of the fluid, a solvent for resin decomposition in a liquid state is generated and a liquid solvent supply step is performed. Thereby, in the resin decomposition step, the matrix resin can be efficiently decomposed by the supercritical fluid or subcritical fluid derived from the preheating fluid newly introduced into the reaction processing vessel. Also, in the liquid solvent supply process, the preheated fluid introduced into the reaction processing vessel gradually changes in temperature as the temperature is lowered, so that the matrix resin decomposition process continues in the initial stage of the resin decomposition process. Gradually move to the resin decomposition process. Thereby, it is possible to accurately decompose the matrix resin while suppressing insufficient decomposition of the matrix resin.

Another feature of the present invention is that the recycled fiber manufacturing method further includes a solvent recovery step of recovering a solvent for resin decomposition from the fluid discharged from the reaction processing vessel in the recycled fiber manufacturing method, The fluid generation step and the liquid solvent supply step are to use the resin decomposition solvent recovered in the solvent recovery step.

According to another feature of the present invention configured as described above, the recycled fiber manufacturing method recovers the resin decomposition solvent used in the critical fluid generation step and the liquid solvent supply step in the solvent recovery step, and again generates the critical fluid generation step. And the liquid solvent supply step. Thereby, the manufacturing method of a recycled fiber can decompose and remove a matrix resin economically.

Another feature of the present invention is that the method for producing recycled fiber includes a back pressure valve for adjusting the pressure in the reaction processing container on the discharge path of the fluid discharged from the reaction processing container. .

According to another feature of the present invention configured as described above, the recycled fiber manufacturing method includes a back pressure valve on the discharge path of the fluid discharged from the reaction processing container. Therefore, in the liquid solvent supply step in the recycled fiber manufacturing method, the resin decomposition solvent is stored in a range where the pressure in the reaction processing container is less than the back pressure of the back pressure valve, and the fiber reinforced resin is configured in the reaction processing container. The fiber part to be immersed is immersed in the resin decomposition solvent. Thereby, the matrix resin adhering to the fiber part constituting the fiber reinforced resin or the decomposition product of the matrix resin can be separated from the fiber part, and the matrix resin can be decomposed and removed with higher accuracy. In addition, after the liquid solvent supply step is completed, the resin-decomposing solvent in the reaction processing container can be continuously discharged from the reaction processing container by opening the back pressure valve to the atmosphere. It is possible to accurately collect the matrix resin or the decomposition product of the matrix resin present in the fiber portion, the reaction processing container, and the discharge path.

Another feature of the present invention is that in the method for producing recycled fiber, the reaction treatment container has a vent hole through which the fluid in the reaction treatment container can flow, and fiber reinforced resin is used as the inner peripheral surface of the reaction treatment container. A workpiece support that can be supported in a floating state, and the workpiece placement step is to support the fiber reinforced resin on the workpiece support.

According to the other characteristic of this invention comprised in this way, the manufacturing method of a recycled fiber is performed in the state by which the fiber reinforced resin is arrange | positioned at the workpiece support body provided in the reaction processing container. In this case, the workpiece support supports the fiber reinforced resin in a state where the fiber reinforced resin is floated in the reaction processing container, that is, in a state where it does not contact the inner wall surface of the reaction processing container. Thereby, in the resin decomposition step and the liquid solvent supply step in the manufacturing method of recycled fiber, the position and orientation of the fiber reinforced resin is prevented from changing in the reaction processing container, and the original shape is maintained and the damage is suppressed. Thus, it is possible to collect the fiber portion and prevent a problem such as the processing being delayed by closing the fluid discharge port in the reaction processing container with the fiber reinforced resin or the fiber portion. Further, the matrix resin can be decomposed and removed with high accuracy by preventing the matrix resin from being poorly decomposed at the portion where the fiber reinforced resin is in contact with the inner wall surface of the reaction processing vessel or the matrix resin or the matrix resin being decomposed.

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  Further, the present invention can be implemented not only as a method for producing recycled fibers, but also as an invention for a method for separating a fiber portion and a matrix resin in a fiber reinforced resin and an invention for a recycled fiber production system.

Specifically, the recycled fiber production system includes a critical fluid generating means for generating a critical fluid in a supercritical state or a subcritical state by heating a resin decomposition solvent used for decomposing a matrix resin constituting the fiber reinforced resin. , A reaction treatment container for introducing a critical fluid in a state in which the fiber reinforced resin is contained and performing a decomposition treatment of the matrix resin, and a resin decomposition in a liquid state so as to immerse the fiber reinforced resin disposed in the reaction treatment container It is preferable to include a liquid feed pump that supplies the solvent for use into the reaction processing container and a liquid solvent supply means that supplies the resin decomposition solvent in a liquid state into the reaction processing container after the matrix resin decomposition process.

In this case, in the recycled fiber production system, the critical fluid generating means includes preheated fluid generating means that preheats the resin decomposition solvent outside the reaction processing container to generate a preheated fluid, and the liquid solvent supply means includes: It is preferable to obtain a resin-decomposing solvent in a liquid state by lowering the temperature of the preheating fluid introduced into the reaction processing vessel.

In these cases, the recycled fiber production system further includes solvent recovery means for recovering the resin decomposition solvent from the fluid discharged from the reaction processing container, and the critical fluid generation means and the liquid solvent supply means include the solvent It is preferable to use the resin decomposition solvent recovered by the recovery means.

In these cases, the recycled fiber production system may include a back pressure valve for adjusting the pressure in the reaction processing container on the discharge path of the fluid discharged from the reaction processing container.

Further, in these cases, in the recycled fiber manufacturing system, the reaction processing container has a vent hole through which the fluid in the reaction processing container can flow and the fiber reinforced resin is floated from the inner peripheral surface of the reaction processing container. It is good to provide the workpiece support body which can be supported.

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It is the block diagram which showed typically the system configuration | structure of the recycled fiber manufacturing system used for the manufacturing method of the recycled fiber which concerns on one Embodiment of this invention. It is the flowchart which showed the operation | work process of the manufacturing method of the recycled fiber which concerns on this invention. (A) is an electron micrograph of the fiber part which removed the matrix resin from the fiber reinforced resin in the experiment results of the present inventors, and (B) is under the same conditions as the experiment in (A) by the present inventors. It is an electron micrograph of the fiber part which removed the matrix resin from the fiber reinforced resin in another experimental result performed. It is the graph which showed the relationship between the solubilization rate for every kind of solvent for resin decomposition | disassembly, and reaction time. It is the graph which showed the relationship between the solubilization rate at the time of using acetone as a solvent for resin decomposition | disassembly, and reaction time. It is the block diagram which showed typically the system configuration | structure of the recycled fiber manufacturing system used for the manufacturing method of the recycled fiber which concerns on the modification of this invention.

  Hereinafter, an embodiment of a method for producing recycled fiber according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically showing a system configuration of a recycled fiber production system 100 used in the method for producing recycled fiber according to the present invention. Note that the drawings referred to in this specification are schematically shown by exaggerating some of the components in order to facilitate understanding of the present invention. For this reason, the dimension, ratio, etc. between each component may differ. The recycled fiber manufacturing system 100 is a group of mechanical devices that decompose and remove a matrix resin constituting the fiber reinforced resin F such as a carbon fiber reinforced resin and a glass fiber reinforced resin, and collect the fiber portion as a reusable recycled fiber. . Here, as the fiber reinforced resin F, a thermosetting resin (for example, unsaturated polyester resin, epoxy resin, phenol resin) or a thermoplastic resin (for example, polypropylene, polyamide resin) in a bundle of fibers such as carbon fiber and glass fiber. , Methyl methacrylate) and other resin components are impregnated as a matrix resin.

(Configuration of recycled fiber manufacturing system 100)
The recycled fiber manufacturing system 100 includes a solvent storage tank 101. The solvent storage tank 101 is an iron container for storing the liquid resin decomposition solvent C. The solvent storage tank 101 can store an amount of the resin decomposing solvent C that can circulate the resin decomposing solvent C when the recycled fiber manufacturing system 100 is operated. The resin-decomposing solvent C is a substance used for decomposing the matrix resin constituting the fiber reinforced resin F and removing it from the fiber portion, and is composed of a substance that easily dissolves the matrix resin. In the present embodiment, the resin-decomposing solvent C is composed of acetone.

A supply pipe 102 is connected to the solvent storage tank 101. The supply pipe 102 is a pipe for guiding the resin-decomposing solvent C stored in the solvent storage tank 101 to the reaction processing container 106, and a terminal portion is connected to the reaction processing container 106. A liquid feed pump 103, a preheater 104, and a valve 105 are provided on the piping path of the supply pipe 102.

The liquid feed pump 103 is a mechanical device that sucks the resin decomposition solvent C stored in the solvent storage tank 101 and sends it to the reaction processing vessel 106, and its operation is controlled by a control device 120 described later. The preheater 104 is a heating device that heats the resin decomposition solvent C sent to the reaction processing vessel 106 to a predetermined temperature by an electric heating coil 104 a disposed on the outer periphery of the supply pipe 102, and its operation is controlled by the control device 120. The In this case, the predetermined temperature at which the preheater 104 heats the resin decomposition solvent C is a temperature at which the resin decomposition solvent C is brought into a supercritical state, that is, a temperature close to the critical temperature of the resin decomposition solvent C.

In the present embodiment, the preheater 104 heats the resin decomposition solvent C to about 225 ° C. because the critical temperature of the resin decomposition solvent C made of acetone is 235 ° C. The temperature close to the critical temperature of the resin decomposing solvent C when the preheater 104 heats the resin decomposing solvent C is preferably in the range of −5% to the critical temperature of the resin decomposing solvent C. is there. The valve 105 is a manual valve for adjusting the flow rates of the supercritical resin decomposition solvent C and the liquid resin decomposition solvent C supplied into the reaction processing vessel 106.

  The reaction processing container 106 is a container for decomposing the fiber reinforced resin F, and is formed of a cylindrical body extending slightly inclined with respect to the horizontal direction. In this case, the inclination of the reaction processing vessel 106 is a so-called water gradient for facilitating the discharge of the liquid resin-decomposing solvent C supplied into the reaction processing vessel 106, and an inclination in the range of approximately 1 to 10 °. It is set to the corner.

  The reaction processing vessel 106 is made of a material that can withstand the processing temperature (300 ° C. in the present embodiment) and the processing pressure (5 MPa in the present embodiment) of the fiber reinforced resin F, for example, stainless steel. Further, the reaction processing vessel 106 formed in a cylindrical shape is configured such that one end (the left side in the figure) can be opened and closed as a door 106a and the other end (the right side in the figure) is closed. .

  The inside of the reaction processing vessel 106 is a region for decomposing the fiber reinforced resin F, and is formed with liquid-tightness and air-tightness, respectively. Inside the reaction processing vessel 106, a temperature sensor 106b and a workpiece support 107 are provided. The temperature sensor 106 b is a detector for detecting the temperature inside the reaction processing vessel 106. Each temperature sensor 106 b is connected to the control device 120 and outputs a detection signal to the control device 120. In addition, a pressure gauge (not shown) is also provided in the reaction processing vessel 106 so that the pressure in the reaction processing vessel 106 can be monitored.

  The workpiece support 107 is a container that can support the fiber reinforced resin F in a state of floating from the inner wall peripheral surface so that the fiber reinforced resin F does not contact the inner wall surface of the reaction processing container 106 in the reaction processing container 106. . The workpiece support 107 has a vent hole through which a critical fluid introduced into the reaction processing vessel 106 and a decomposition product of the matrix resin constituting the fiber reinforced resin F can flow.

  Specifically, the workpiece support 107 is configured in a bowl shape in which a plate-like net member made of stainless steel is formed in a cylindrical shape. In this case, one end (the left side in the figure) of the both ends of the workpiece support 107 formed in a cylindrical shape is closed by a plate-shaped mesh member so that it can be opened and closed, and the other end (the right side in the figure) is the same. The plate-like net member is fixedly closed. That is, the fiber reinforced resin F is put in and out from one end (left side in the drawing) of the reaction processing vessel 106 and the workpiece support 107.

  The workpiece support 107 is supported in a floating state in the reaction processing vessel 106 so that the cylindrical outer peripheral portion does not contact the inner wall surface of the reaction processing vessel 106. In the present embodiment, the workpiece support 107 is supported by shafts that protrude from two wall surfaces at both ends in the longitudinal direction of the reaction processing vessel 106. Note that the method for supporting the workpiece support 107 in the reaction processing vessel 106 is not limited to the present embodiment. For example, a support leg is provided at the bottom of the workpiece support 107 and the bottom of the reaction treatment vessel 106 is provided. It can also be supported in a mounted state.

  On the other hand, the supply pipe 102 is connected to the outer peripheral portion of the reaction processing vessel 106 in a state where it communicates with the inside of the reaction processing vessel 106 at the upper portion, and at the lowermost portion of the reaction processing vessel 106 inside the reaction processing vessel 106. A discharge pipe 108 is connected in a communicating state. The discharge pipe 108 is a pipe for discharging the fluid in the reaction processing container 106 from the reaction processing container 106. In this case, the fluid in the reaction processing vessel 106 includes a supercritical or subcritical resin decomposition solvent C and a liquid resin decomposition solvent C. In the following description, the fluid discharged from the reaction processing vessel 106 may be referred to as “discharged fluid”.

  Further, the electrothermal coil 109 is wound around the entire periphery of the reaction processing vessel 106 over the entire circumference. The electric heating coil 109 is a heating device whose operation is controlled by the control device 120, and heats the temperature inside the reaction processing vessel 106 to 300 ° C. and maintains the same temperature state. That is, in this embodiment, the reaction processing vessel 106 is a so-called electric furnace. In this embodiment, the electrothermal coil 109 heats the resin decomposition solvent C made of acetone to 300 ° C. (pressure is 5 MPa) to generate a supercritical fluid. Acetone has a critical temperature of 235 ° C. and a critical pressure of 4.6 MPa.

On the piping path of the discharge pipe 108, a cooler 110 and a back pressure valve 111 are provided. The cooler 110 is a mechanical device for cooling the discharged fluid discharged from the reaction processing vessel 106 in order to protect the back pressure valve 111. Specifically, the cooler 110 cools the discharge pipe 108 by a water cooling method, thereby lowering the temperature of the discharged fluid discharged from the reaction processing vessel 106 to about 60 ° C. The operation of the cooler 110 is controlled by the control device 120. The back pressure valve 111 opens the valve when the pressure in the exhaust pipe 108 and the reaction processing vessel 106 upstream of the back pressure valve 111 reaches a predetermined pressure, and opens the exhaust pipe 108 and the reaction processing vessel 106. always under vacuum a device for maintaining below a predetermined pressure. In the present embodiment, the predetermined pressure of the back pressure valve 111 is set to 5 MPa in order to maintain the resin decomposition catalyst C made of acetone in a supercritical state.

  A solvent separator 112 is provided at the end of the discharge pipe 108. The solvent separator 112 is a gas-liquid separation tank for recovering the resin decomposition solvent C from the discharged fluid discharged from the reaction processing vessel 106. Specifically, the solvent separator 112 stores the fluid discharged from the reaction processing vessel 106 guided from the discharge pipe 108 at a predetermined temperature (about 50 ° C. in the present embodiment) while reducing the pressure. In this case, the degree of pressure reduction in the solvent separator 112 is preferably such that the boiling point of the resin decomposition solvent C is about 40 to 60 ° C. A solvent recovery tube 113 is provided at the top of the solvent separator 112. The solvent recovery tube 113 is a pipe for recovering the resin decomposition solvent C vaporized in the solvent separator 112 from the solvent separator 112. A cooler 114 and a vacuum pump 115 are connected on the piping path of the solvent recovery pipe 113.

The cooler 114 is a mechanical device that liquefies the solvent recovery pipe 113 by cooling it to about 10 ° C. by cooling the solvent recovery pipe 113 by a water cooling method to lower the temperature of the resin decomposition solvent C in a gaseous state. The operation of the cooler 114 is controlled by the control device 120. The vacuum pump 115 is a mechanical device for generating a negative pressure in the solvent separator 112 via the solvent recovery tube 113 to reduce the pressure of the solvent separator 112. A solvent recovery tank 116 is provided at the end of the solvent recovery tube 113. The solvent recovery tank 116 is a container for temporarily storing the resin decomposition solvent C liquefied by the cooler 114. The solvent recovery tank 116 is disposed at a position higher than the solvent storage tank 101 and is connected to the solvent storage tank 101 via a solvent reflux pipe 117. As a result, the resin-decomposing solvent C recovered in the solvent recovery tank 116 returns to the solvent storage tank 101 through the solvent reflux pipe 117 by natural fall. The solvent reflux pipe 117 is a pipe for returning the liquid resin decomposition solvent C stored in the solvent recovery tank 116 to the solvent storage tank 101.

  The control device 120 is configured by a microcomputer including a CPU, a ROM, a RAM, and the like, and an input device (not shown) for inputting instructions from the worker and the recycled fiber manufacturing system 100 for the worker. Is provided with a display device (not shown) for displaying the operation status. The control device 120 controls the start and stop of each operation of the liquid feed pump 103, the preheater 104, the electric heating coil 109, the coolers 110 and 114, and the vacuum pump 115 according to the operation of the operator. In addition, the control device 120 controls the operation of the electric heating coil 109 so that the temperature in the reaction processing container 106 maintains the set temperature using the detection signal from the temperature sensor 106 b installed in the reaction processing container 106.

(Operation of recycled fiber manufacturing system 100)
Next, the operation of the recycled fiber production system 100 configured as described above, that is, the method for producing recycled fiber according to the present invention will be described with reference to FIG. First, the worker performs a work placement process as a first process. Specifically, the worker accommodates the fiber reinforced resin F in the work support 107 in the reaction processing vessel 106. Thereby, the fiber reinforced resin F is arrange | positioned in the state which floated with respect to the inner wall surface in the reaction processing container 106. FIG.

  Next, the operator turns on a power switch (not shown) in the recycled fiber manufacturing system 100 and then introduces a liquid resin-decomposing solvent C into the reaction processing vessel 106. Specifically, the operator starts the operation of the liquid feeding pump 103 by operating the control device 120 to introduce a part of the resin decomposition solvent C in the solvent storage tank 101 into the reaction processing vessel 106. . In this case, the operator introduces into the reaction processing vessel 106 a resin-decomposing solvent C in an amount that completely immerses the fiber reinforced resin F disposed in the reaction processing vessel 106. In the operation of introducing the resin decomposition solvent C into the reaction processing vessel 106, the operator naturally opens the valve 105. Further, the operator closes the valve 105 when the predetermined amount of the resin decomposition solvent C has been introduced into the reaction processing vessel 106.

  Next, an operator performs a critical fluid production | generation process as a 2nd process. Specifically, the operator operates the control device 120 to start the operation of the electric heating coil 109 to heat the temperature in the reaction processing vessel 106 to 300 ° C. and maintain the same temperature. As a result, the temperature and pressure in the reaction processing vessel 106 rise, and the resin decomposition solvent C accommodated in the reaction processing vessel 106 gradually becomes a critical fluid in a supercritical state. In the process in which the resin-decomposing solvent C is transferred to the critical fluid, the fiber reinforced resin F is completely immersed in the liquid resin-decomposing solvent C. The resin-decomposing solvent C can be transferred to the critical fluid without being carbonized. Moreover, when matrix resin is comprised with the thermosetting resin, hardening of matrix resin can be prevented. That is, the electrothermal coil 109 corresponds to the critical fluid generating means according to the present invention.

  Next, an operator performs a resin decomposition process as a 3rd process. Specifically, in the resin decomposition step, the decomposition treatment of the fiber reinforced resin F is started when the liquid resin decomposition solvent C in the reaction processing vessel 106 becomes a critical fluid. In addition, the operator starts each operation of the liquid feed pump 103, the preheater 104, the coolers 110 and 114, and the vacuum pump 115 by operating the control device 120. As a result, the preheater 104 heats the resin decomposition solvent C guided from the solvent storage tank 101 to about 225 ° C. to generate a preheating fluid. Then, the operator introduces the preheated fluid generated by the preheater 104 into the reaction processing vessel 106 by opening the valve 105. That is, the preheater 104 corresponds to the preheating fluid generating means according to the present invention.

Therefore, in the reaction processing vessel 106, the fiber-reinforced resin F is decomposed in a state where the supercritical state is maintained while introducing the preheating fluid. In this case, the inside of the reaction processing vessel 106 is maintained at a predetermined pressure (5 MPa) by the back pressure valve 111 . That is, the fluid existing in the reaction processing vessel 106 is discharged from the reaction processing vessel 106 by the pressure adjustment function of the back pressure valve 111 . For this reason, in the reaction processing vessel 106, the matrix resin constituting the fiber reinforced resin F is decomposed by the critical fluid that is the resin decomposition solvent C in the supercritical state, and the decomposition products generated by the decomposition of the matrix resin. Is dissolved in the critical fluid or discharged from the reaction processing vessel 106 together with the critical fluid.

  Further, at the time of the decomposition process of the matrix resin, the fiber reinforced resin F is accommodated in the work support 107 and supported while being floated from the inner wall surface of the reaction processing vessel 106. For this reason, it is prevented that the fiber reinforced resin F is exposed to the atmosphere of the critical fluid and the non-contact portion to the critical fluid is generated. Thereby, the fiber reinforced resin F is effectively decomposed without unevenness while suppressing the decomposition leakage of the matrix resin.

The discharged fluid discharged from the reaction processing vessel 106 via the discharge pipe 108 is cooled and liquefied by the cooler 110 and then led to the solvent separator 112 via the back pressure valve 111. In this case, since the inside of the solvent separator 112 is depressurized by the vacuum pump 115, the resin decomposition solvent C contained in the exhausted fluid is vaporized from the exhausted fluid guided into the solvent separator 112. On the other hand, the decomposition product of the matrix resin contained in the discharged fluid is stored in the solvent separator 112 while maintaining a liquid state. The resin-decomposing solvent C vaporized in the solvent separator 112 is led to the cooler 114 via the solvent recovery pipe 113 and liquefied again, and then stored in the solvent recovery tank 116. The resin-decomposing solvent C stored in the solvent recovery tank 116 returns to the solvent storage tank 101 by natural fall through the solvent reflux pipe 117. Thereby, the resin decomposition solvent C returned to the solvent storage tank 101 is used again for the decomposition of the fiber reinforced resin F. That is, the recycled fiber manufacturing system 100 in the present embodiment circulates the resin decomposition solvent C in the recycled fiber manufacturing system 100 and repeatedly uses it for the decomposition treatment of the fiber reinforced resin F. The solvent separator 112 corresponds to the solvent recovery means according to the present invention.

  The resin decomposing step for decomposing the fiber reinforced resin F is performed until the matrix resin existing around the fiber portion constituting the fiber reinforced resin F is dissolved and separated from the fiber portion. Specifically, the time of the resin decomposition step depends on the amount, shape, and size of the fiber reinforced resin F, the type of the solvent C for resin decomposition, the processing temperature, and the processing pressure. Minutes are appropriate.

  Next, an operator performs a liquid solvent supply process as a 4th process. Specifically, the operator stops the operations of the preheater 104 and the electric heating coil 109 by operating the control device 120. As a result, the temperature and pressure of the preheated fluid supplied into the reaction processing vessel 106 are gradually lowered and liquefied, and the temperature and pressure in the reaction processing vessel 106 are also gradually reduced to reduce the critical fluid in the reaction processing vessel 106. Liquefaction. Even while the temperature and pressure in the reaction processing vessel 106 are lowered, the matrix resin is continuously decomposed as long as the critical fluid and the matrix resin exist in the reaction processing vessel 106.

  When the resin decomposition solvent C in the reaction processing vessel 106 is in a liquid state, the decomposition product of the matrix resin is dissolved or floated in the liquid resin decomposition solvent C. In this case, the inside of the reaction processing vessel 106 is continuously maintained at a pressure lower than a predetermined pressure by the back pressure valve 111. For this reason, after the pressure in the reaction processing vessel 106 starts once the liquid solvent supply step is started, the pressure rises again as the liquid-decomposing solvent C for resin decomposition in the reaction processing vessel 106 increases. To do. Accordingly, the resin-decomposing solvent C in the liquid state in the reaction processing container 106 is discharged from the reaction processing container 106 by an amount corresponding to the pressure adjustment by the back pressure valve 111.

  The discharged fluid discharged from the reaction processing vessel 106 in this liquid solvent supply step is guided to the solvent separator 112 via the cooler 110 and the back pressure valve 111, and the resin decomposition solvent C is recovered in the same manner as described above. Finally, it returns to the solvent storage tank 101. This liquid solvent supply step is performed until the remaining amount of the decomposition product of the matrix resin present in the reaction processing vessel 106 is reduced to a predetermined amount. Specifically, the treatment time depends on the amount, shape, and size of the fiber reinforced resin F, the type of the solvent C for resin decomposition, the treatment temperature and the treatment pressure in the second step, and is approximately 60 minutes. ~ 150 minutes is appropriate.

Next, the worker performs a workpiece removal step as a fifth step. Specifically, the operator stops the operations of the liquid feed pump 103 and the cooler 110 and opens the back pressure valve 111 to open the atmosphere. As a result, the liquid resin decomposition solvent C stored in the reaction processing vessel 106 is discharged from the reaction processing vessel 106 and collected in the solvent separator 112. In this case, the decomposition product of the matrix resin dissolved or suspended in the liquid resin decomposition solvent C stored in the reaction processing vessel 106 and the decomposition of the matrix resin remaining in the discharge pipe 108 The product is discharged from the reaction processing vessel 106 together with the resin-decomposing solvent C and collected in the solvent separator 112. In this case, the reaction processing vessel 106 is inclined with respect to the horizontal direction, and the discharge pipe 108 is provided at the lowermost portion of the reaction processing vessel 106 in the inclined state. The resin decomposition solvent C can be discharged from the reaction processing vessel 106.

Further, in the discharging process of the resin decomposing solvent C, the fiber reinforced resin F from which the matrix resin has been removed, that is, the fiber portion constituting the fiber reinforced resin F is held in the work support 107. There is no movement or entanglement during the discharge of the solvent C for resin decomposition. As a result, the resin-decomposing solvent C is discharged in a state where the original shape of the fiber reinforced resin F is retained and damage is suppressed. The decomposition product of the matrix resin adhering to the work support 107 due to the discharge of the resin decomposition solvent C is also flowed together with the resin decomposition solvent C. The discharged fluid discharged from the reaction processing vessel 106 is guided to the solvent separator 112 via the cooler 110 and the back pressure valve 111, and the resin decomposition solvent C is recovered in the same manner as described above to finally store the solvent. Return to tank 101.

  When all of the resin decomposition solvent C is discharged from the reaction processing container 106, the operator opens the reaction processing container 106 and collects the fiber portion remaining in the work support 107. Further, the operator operates the control device 120 to stop the operations of the cooler 114 and the vacuum pump 115. As a result, the decomposition product of the matrix resin constituting the fiber reinforced resin F is recovered in the solvent separator 112. The decomposition product of the matrix resin recovered in the solvent separator 112 can be reused alone or mixed with other petroleum fuel.

  In addition, the present inventors observed the fiber part collected by this recycled fiber manufacturing system 100 with an electron microscope and performed a tensile test. As a result, the present inventors confirmed that the matrix resin was removed from the fiber portion constituting the fiber reinforced resin F as shown in FIGS. 3 (A) and 3 (B). In addition, the present inventors have found that the tensile strength of the fiber portion recovered by the recycled fiber manufacturing system 100 is about 10% lower than that of a new fiber material having the same composition as the fiber portion. It was confirmed. That is, the present inventors have confirmed that according to the method for producing recycled fiber according to the present invention, the fiber portion contained in the fiber reinforced resin F can be produced as a reusable recycled fiber using the fiber reinforced resin F as a raw material. .

As can be understood from the above description of the operation, according to the above embodiment, the recycled fiber production method includes the reaction treatment after decomposing the matrix resin in the reaction treatment vessel 106 in which the solvent C for resin decomposition is in a supercritical state. The resin decomposition solvent C in a liquid state is introduced into the container 106 to discharge the fluid in the reaction processing container 106 while lowering the temperature in the reaction processing container 106. That is, in the method for producing recycled fiber according to the present invention, the matrix resin constituting the fiber reinforced resin F is solubilized with a supercritical fluid, and then the resin decomposition solvent C in a liquid state is introduced into the reaction processing vessel 106. Thus, the degradation product of the solubilized matrix resin is dissolved in the fiber component constituting the fiber reinforced resin F or in the reaction processing vessel 106 while lowering the temperature in the reaction processing vessel 106 . As a result, in the process of decomposing the fiber reinforced resin F, the supercritical state maintenance time can be shortened, and the fiber portion can be efficiently recovered to produce recycled fibers.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

For example, in the above-described embodiment, a supercritical fluid in which the resin-decomposing solvent C is heated to 300 ° C. and pressurized to 5 MPa to be in a supercritical state is used as a critical fluid for decomposing the fiber reinforced resin F. However, a subcritical fluid in which the resin decomposition solvent C is in a subcritical state can also be used as the critical fluid. According to this, since the fiber reinforced resin F can be decomposed at a lower temperature and pressure than in the case where the critical fluid is composed of a supercritical fluid, damage to the finally recovered fiber portion can be suppressed. According to the experiments by the present inventors, when acetone is used as the critical fluid, the resin-decomposing solvent C made of acetone is heated in the range of 250 to 350 ° C. and in the range of 0.5 to 5 MPa . It is preferable to use in a pressurized supercritical state or subcritical state.

  Moreover, in the said embodiment, acetone was used as the solvent C for resin decomposition. This is because the rate of increase of the solubilization rate of the matrix resin in the critical fluid with respect to time is relatively fast. FIG. 4 shows the dissolution rate (solubilization rate) of the decomposition product of the epoxy resin in the liquid decomposition solvent C when the epoxy resin is decomposed with a critical fluid in a supercritical state (300 ° C., 10 MPa). It is a graph which shows the result of having experimented the change with respect to reaction time for every three solvent C for resin decomposition | disassembly (acetone, 1-propanol, 2-propanol). According to the experiment of the present inventors shown in FIG. 4, it can be confirmed that the use of acetone as the resin decomposition solvent C is the fastest way to dissolve the epoxy resin.

  FIG. 5 shows the dissolution rate (solubilization rate) of the decomposition product of the epoxy resin in the liquid decomposition solvent C when the epoxy resin is decomposed with a critical fluid in a subcritical state (320 ° C., 1 MPa). It is a graph which shows the result of having experimented with the solvent C for resin decomposition | disassembly which consists of acetone about the change with respect to reaction time. According to the experiments of the present inventors shown in FIG. 5, when acetone is used as the resin decomposition solvent C, the resin decomposition solvent C made of liquid acetone is supplied after about 20 minutes of decomposition treatment time. Thus, the epoxy resin can be dissolved and removed almost completely. Therefore, from these experimental results, the decomposition treatment time of the fiber reinforced resin F can be shortened by using acetone as the solvent C for resin decomposition.

  However, the experimental results shown in FIGS. 4 and 5 do not mean that the resin decomposition solvent C is limited to acetone. The resin decomposition solvent C that can be used in the present invention is not necessarily limited to the above embodiment as long as it becomes a critical fluid and can decompose the fiber reinforced resin F. For example, alcohol (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, etc.) or water can be used as the solvent C for resin decomposition. In addition, the matrix resin which comprises the fiber reinforced resin F can also be collect | recovered as resin by using alcohol as the solvent C for resin decomposition | disassembly.

  Moreover, in the said embodiment, in order to make the solvent C for resin decomposition into a supercritical state, the electrothermal coil 109 was used. That is, the electrothermal coil 109 corresponds to the critical fluid generating means according to the present invention. However, the critical fluid generating means is not necessarily limited to the above embodiment as long as the critical fluid can exist in the reaction processing vessel 106. For example, the electrothermal coil 109 may be eliminated and the critical fluid may be generated by the preheater 104.

  In the above embodiment, the preheater 104 is used to heat the resin decomposition solvent C in advance of the reaction processing vessel 106. That is, the preheater 104 corresponds to preheating means according to the present invention. As a result, the fiber-reinforced resin F can be decomposed while supplying a new resin-decomposing solvent C while suppressing the temperature drop in the reaction processing vessel 106. However, in the method for producing recycled fiber according to the present invention, the preheating means is not necessarily required. For example, the resin-decomposing solvent C is changed to a critical fluid only by the electric heating coil 109 provided on the outer periphery of the reaction processing vessel 106, and the fiber-reinforced resin F is decomposed in the sealed reaction processing vessel 106. You can also

  Moreover, in the said embodiment, while setting the reaction processing container 106 to the horizontal type extended in a horizontal direction, it provided in the state inclined with respect to the horizontal direction. However, the reaction processing vessel 106 is not limited to the above embodiment as long as it is a vessel capable of processing the fiber reinforced resin F with a critical fluid composed of the resin decomposition solvent C. For example, the reaction processing vessel 106 may be configured as a horizontal type extending parallel to the horizontal direction, or may be configured as a vertical type extending parallel to the vertical direction. Note that. In the case where the reaction processing vessel 106 is configured as a vertical type, the supply pipe 102 may be installed on the upper side of the reaction processing vessel 106 and the discharge pipe 108 may be installed on the bottom side of the reaction processing vessel 106.

  In the above embodiment, one supply pipe 102 and one discharge pipe 108 are provided for the reaction processing vessel 106. However, a plurality of supply pipes 102 and discharge pipes 108 can be provided for each reaction processing vessel 106. In this case, the supply pipe 102 and the discharge pipe 108 can be provided along the longitudinal direction and the circumferential direction of the reaction processing vessel 106 with respect to the reaction processing vessel 106, respectively. In these cases, the supply pipe 102 can be secured above the discharge pipe 108 to ensure the discharge of the fluid in the reaction processing vessel 106.

  Moreover, in the said embodiment, the liquid solvent supply process was made to obtain the liquid resin decomposition solvent C by gradually reducing the temperature of the preheating fluid which started supply by the resin decomposition process. However, the liquid solvent supply step is not necessarily limited to the above embodiment as long as the liquid resin decomposition solvent C can be introduced into the reaction processing vessel 106.

  For example, as shown in FIG. 6, three-way valves 131a and 131b are provided on the upstream and downstream sides of the preheater 104 on the supply pipe 102, respectively, and a liquid solvent supply pipe 132 is provided between these two three-way valves 131a and 131b. Connect. That is, the recycled fiber manufacturing system 100 is configured by providing a pipeline for introducing the liquid resin decomposition solvent C into the reaction processing vessel 106 by bypassing the preheater 104 on the supply pipe 102. The recycled fiber manufacturing system 100 controls the opening and closing of the three-way valves 131a and 131b after the resin decomposition step in the liquid solvent supply step to cut off the supply of the resin decomposition solvent C to the preheater 104 and supply the liquid solvent. The liquid resin decomposition solvent C is directly introduced into the reaction processing vessel 106 from the tube 132. According to this, the processing time of the liquid solvent supply step can be further shortened.

  Moreover, in the said embodiment, the solvent C for resin decomposition | disassembly was collect | recovered from the discharged | emitted fluid discharged | emitted from the inside of the reaction processing container 106, and it used again in the resin decomposition | disassembly process and the liquid solvent supply process. That is, the step of recovering the resin decomposition solvent C from the discharged fluid in the solvent separator 112 corresponds to the solvent recovery step according to the present invention. However, when the resin decomposition solvent C is used only in a single resin decomposition step or liquid solvent supply step, that is, when the resin decomposition solvent is made disposable, the solvent recovery step can be omitted.

Further, in the above embodiment, the reaction processing vessel 106 is configured to use the back pressure valve 111 in order to maintain the pressure necessary for maintaining the supercritical state or the subcritical state and to prevent an excessive pressure increase. . However, the embodiment is not necessarily limited to the above-described embodiment as long as the inside of the reaction processing vessel 106 can be maintained at a pressure necessary to maintain the supercritical state or the subcritical state and an excessive pressure increase can be prevented. For example, instead of the back pressure valve 111, the pressure in the reaction processing vessel 106 can be maintained within a predetermined pressure range by an electromagnetic valve whose opening / closing operation is controlled by the control device 120. According to this, processing can be performed under different pressure conditions in the resin decomposition processing step and the liquid solvent supply step. For example, in the liquid solvent supply step, the processing time can be shortened by continuously supplying and discharging the resin decomposition solvent C in the liquid state by always opening the solenoid valve. .

In the above embodiment, the cylindrical workpiece support 107 is used to support the fiber reinforced resin F in the reaction processing vessel 106. However, if the workpiece support 107 can support the fiber reinforced resin in a state of being floated from the inner peripheral surface of the reaction processing vessel 106 while having a vent hole through which the fluid in the reaction processing vessel 106 can flow, the workpiece support 107 is not necessarily provided. It is not limited to the embodiment. For example, the workpiece support 107 may be formed in a box shape of a rectangular parallelepiped, a cube, or a cone using a net or a plate-like body having a plurality of through holes, or may be formed in a table shape or a table shape. it can. Moreover, in the manufacturing method of the recycled fiber which concerns on this invention, the workpiece | work support body 107 is not necessarily required. That is, the fiber reinforced resin may be provided directly in the reaction processing vessel 106. In this case, in order to prevent clogging of the discharge pipe 108 due to the fiber portion from which the matrix resin has been removed, care should be taken such as providing a position on the discharge pipe 108 or providing a filter on the discharge pipe 108.

F: Fiber reinforced resin, C: Solvent for resin decomposition,
100: Recycled fiber manufacturing system 100,
DESCRIPTION OF SYMBOLS 101 ... Solvent storage tank, 102 ... Supply pipe, 103 ... Liquid feed pump, 104 ... Preheater, 104a ... Electric heating coil, 105 ... Valve, 106 ... Reaction processing container, 106a ... Door, 106b ... Temperature sensor, 107 ... Work support 108, exhaust pipe, 109 ... electric heating coil, 110, 114 ... cooler, 111 ... back pressure valve, 112 ... solvent separator, 113 ... solvent recovery pipe, 115 ... vacuum pump, 116 ... solvent recovery tank, 117 ... solvent Reflux tube,
120 ... control device,
131a, 131b ... three-way valve, 132 ... liquid solvent supply pipe.

Claims (10)

A resin-decomposing solvent used for decomposing the matrix resin constituting the fiber-reinforced resin;
A critical fluid generating means for generating a critical fluid in which the solvent for resin decomposition is heated to a supercritical state or a subcritical state;
A method for producing recycled fibers using a reaction treatment container for containing the fiber reinforced resin and performing a decomposition treatment of the matrix resin,
After placing the fiber reinforced resin in the reaction treatment container, a work placement step of immersing the fiber reinforced resin by introducing the resin decomposition solvent in a liquid state into the reaction treatment container ;
A critical fluid generating step of generating the critical fluid by the critical fluid generating means;
A resin decomposing step of decomposing the matrix resin in the fiber reinforced resin disposed in the reaction processing vessel using the critical fluid;
Wherein after the resin decomposition step, the reaction processing vessel liquid solvent feed to lower the temperature of the fluid the reaction processing vessel while discharging a present in the reaction processing chamber while introducing the resin cracking solvent in the liquid state into the A process for producing a recycled fiber comprising the steps of: In the manufacturing method of the recycled fiber of Claim 1,
The critical fluid generating means includes
Preheating fluid generating means for generating a preheating fluid by preheating the solvent for resin decomposition outside the reaction processing vessel,
The resin decomposition step includes
Performing the decomposition treatment of the matrix resin while discharging the fluid in the reaction processing vessel while introducing the preheating fluid generated by the preheating fluid generating means into the reaction processing vessel;
The liquid solvent supply step includes
A method for producing recycled fiber, wherein the resin-decomposing solvent in the liquid state is obtained by lowering the temperature of the preheating fluid introduced into the reaction processing vessel. In the manufacturing method of the recycled fiber according to claim 1 or 2, further,
Including a solvent recovery step of recovering the resin decomposition solvent from the fluid discharged from the reaction processing vessel,
The critical fluid generation step and the liquid solvent supply step include
A method for producing a recycled fiber, wherein the solvent for resin decomposition recovered in the solvent recovery step is used. In the manufacturing method of the recycled fiber as described in any one of Claim 1 thru | or 3,
A method for producing recycled fiber, comprising a back pressure valve for adjusting a pressure in the reaction processing container on a discharge path of a fluid discharged from the reaction processing container. In the manufacturing method of the recycled fiber as described in any one of Claims 1 thru | or 4,
The reaction processing container
A work support that can support the fiber reinforced resin in a state of floating from the inner peripheral surface of the reaction processing container while having a vent hole through which the fluid in the reaction processing container can flow;
The workpiece placement step includes:
A method for producing a recycled fiber, comprising supporting the fiber reinforced resin on the work support. A critical fluid generating means for generating a critical fluid in a supercritical state or a subcritical state by heating a solvent for resin decomposition used for decomposing the matrix resin constituting the fiber reinforced resin;
A reaction processing container for introducing the critical fluid in a state in which the fiber reinforced resin is contained and performing a decomposition process of the matrix resin;
A liquid feed pump for supplying the resin-decomposing solvent in a liquid state to the extent that the fiber-reinforced resin disposed in the reaction processing container is immersed in the reaction processing container;
A recycled fiber production system comprising: a liquid solvent supply means for supplying the resin decomposition solvent in a liquid state into the reaction processing container after the decomposition treatment of the matrix resin.
In the recycled fiber manufacturing system according to claim 6,
The critical fluid generating means includes
Preheating fluid generating means for generating a preheating fluid by preheating the solvent for resin decomposition outside the reaction processing vessel,
The liquid solvent supply means includes
Recycled fiber manufacturing system according to claim Rukoto obtain a resin decomposed solvent for the liquid state by lowering the temperature of the preheated fluid is introduced into the reaction process chamber. In the recycled fiber manufacturing system according to claim 6 or 7,
Comprising a solvent recovery means for recovering the resin decomposing solvent from the fluid discharged from the reaction processing vessel;
The critical fluid generation means and the liquid solvent supply means are:
Recycled fiber manufacturing system according to claim Rukoto using the resin cracking solvent recovered in the solvent recovery unit. In the recycled fiber manufacturing system according to any one of claims 6 to 8,
Recycled fiber manufacturing system according to claim Rukoto to have a back pressure valve for adjusting the pressure of said reaction processing vessel on the discharge path of the fluid discharged from the reaction treatment vessel. In the recycled fiber manufacturing system according to any one of claims 6 to 9,
The reaction treatment vessel,
And wherein Rukoto comprising a workpiece support which can be supported in a state in which the fluid of the reaction processing vessel has floated said fiber-reinforced resin while having a distribution can vent from the inner peripheral surface of said reaction processing vessel Recycled fiber manufacturing system.