Hydrolysis continuous processing apparatus

Abstract

To provide a continuous hydrolysis apparatus capable of hydrolyzing a hydrolyzable resin composition using water alone and without using a catalyst and capable of achieving downsizing of a reaction vessel.SOLUTION: A continuous hydrolysis apparatus 1 of the invention includes a hydrolysis vessel 2 equipped with a heating cylinder 8 having a loading port (hopper 13) of a fiber-reinforced resin R and a loading port of water (water inlet 14) and with a screw 9 inserted in the heating cylinder 8 for mixing the fiber-reinforced resin R and the water and conveying the mixture downstream in the heating cylinder 8 and a back pressure valve 3 installed downstream of the hydrolysis vessel 2 for letting a hydrolysis product and fiber flow downstream while setting the pressure in the hydrolysis vessel 2 at a predetermined pressure to promote the hydrolysis reaction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a continuous hydrolysis treatment apparatus Place .

Background Art

[0002] Conventionally, a batch depolymerization apparatus for obtaining ε-caprolactam by depolymerization of nylon 6 in the presence of a catalyst such as phosphoric acid or an ionic liquid is known. For example, in the depolymerization apparatus disclosed in Patent Document 1, in recycling polycaprolactam-containing waste, both the melting and compression treatments of the waste are simultaneously performed in a conventional extruder as a melting apparatus, and then superheated steam and the melt compressed by the melting apparatus are brought into contact with each other in a hydrolysis reactor. The mixture discharged from the hydrolysis reactor is fed to a separation apparatus after being fed to a decompression apparatus. In the separation apparatus, additives such as insoluble glass fibers, pigments, and other polymers are removed. This separation apparatus is composed of a conventional filter apparatus such as a belt filter, a backwashable cylindrical filter, or other filter apparatuses that can be continuously or periodically discharged.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional depolymerization apparatus (for example, see Patent Document 1), since the depolymerization is a batch process by a depolymerization reactor, a large-scale treatment is desired. Also, it is desired to suppress the retention of unreacted substances in the reaction vessel. Furthermore, when carrying out a depolymerization reaction under catalytic conditions, it is necessary to separate and remove the used catalyst from the resulting depolymer containing ε-caprolactam. In addition, in conventional batch-type depolymerization apparatuses that carry out a depolymerization reaction at atmospheric pressure in the presence of a catalyst, there is a problem that the reaction vessel becomes larger if one attempts to increase the amount of nylon 6 decomposed per cycle and thereby increase the yield of ε-caprolactam.

[0005] The object of the present invention is a continuous hydrolysis processing apparatus that can hydrolyze hydrolyzable resin compositions using only water without the use of a catalyst, and that can achieve miniaturization of the reaction vessel. Place The purpose is to provide. [Means for solving the problem]

[0006] The continuous hydrolysis apparatus that solves the above problems comprises a hydrolysis reaction vessel having a heating cylinder having an introduction section for a fiber-containing hydrolyzable resin composition and an introduction section for water, a screw inserted into the heating cylinder and conveying the hydrolyzable resin composition and the water downstream while mixing them, a pressure regulating valve provided downstream of the hydrolysis reaction vessel and setting the pressure in the hydrolysis reaction vessel to a predetermined pressure for the hydrolysis reaction to proceed while allowing the hydrolysis product and fibers to flow downstream, and a sealing section formed from the molten hydrolyzable resin composition and positioned upstream of the water introduction section in the longitudinal direction of the heating cylinder, sealing the gap between the heating cylinder and the screw, The pressure regulating valve is a diaphragm that adjusts the flow path cross-sectional area according to the indicated pressure. The pressure regulating valve is characterized in that when the pressure between the hydrolysis reaction vessel and the pressure regulating valve reaches a preset second pressure that is higher than the first pressure that allows the hydrolysis reaction in the hydrolysis reaction vessel to proceed, the pressure regulating valve increases its opening. [Effects of the Invention]

[0008] According to the present invention, a continuous hydrolysis processing apparatus can be used to hydrolyze hydrolyzable resin compositions using only water without the use of a catalyst, and can also be used to reduce the size of the reaction vessel. Place It can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram illustrating the configuration of a continuous hydrolysis apparatus according to an embodiment of the present invention. [Figure 2] Figure 1 is an exploded perspective view illustrating the configuration of the back pressure valve in the continuous hydrolysis processing apparatus. [Figure 3] Figure 2 is a schematic cross-sectional view illustrating the operation of the back pressure valve. [Figure 4] Figure 1 is a schematic diagram illustrating the operation of the hydrolysis reaction vessel in a continuous hydrolysis processing apparatus. [Modes for carrying out the invention]

[0010] Next, a continuous hydrolysis apparatus and a continuous hydrolysis method according to an embodiment of the present invention will be described in detail. In this embodiment, the present invention will be specifically described using a continuous hydrolysis apparatus and a continuous hydrolysis method for hydrolyzing a fiber-reinforced resin (hydrolyzable resin composition) containing nylon 6 and glass fibers as an example. However, the continuous hydrolysis apparatus and continuous hydrolysis method of the present invention are not limited to this and can also be applied to other hydrolyzable resin compositions described later.

[0011] <Continuous hydrolysis treatment apparatus> As shown in Figure 1, the hydrolysis continuous processing apparatus 1 of this embodiment mainly comprises a hydrolysis reaction vessel 2, a back pressure valve 3, a flash tank 4, a condenser 5, a first dryer 6, and a second dryer 7. Furthermore, the back pressure valve 3 corresponds to the "pressure regulating valve" as referred to in the patent claims.

[0012] In this embodiment, the hydrolysis reaction vessel 2 is assumed to consist of a twin-screw extruder equipped with a heating cylinder 8 and a pair of screws 9. However, the hydrolysis reaction vessel 2 of the present invention is not limited to this and can also be configured to include a single-screw 3. Furthermore, the heating cylinder 8 corresponds to the "heating container" as referred to in the claims. The screw 3 corresponds to the "kneading means" and "conveying means" as referred to in the claims. The heating cylinder 8 includes a cylinder 12 formed by arranging a plurality of cylinder blocks (not shown) in a row in one direction, and a band heater (not shown) disposed on the outer periphery of the cylinder 12. At the rear end on the upstream side of the heating cylinder 8, a fiber reinforced resin R (waste plastic crushed material), which is a waste material containing nylon 6 (PA6) and glass fiber (GF), is introduced via a hopper 13. Also, a water inlet 14 is provided on the downstream side of the hopper 13 in the heating cylinder 8. Water is supplied to this water inlet 14 from a water supply pump 14a via a heater 14b. Note that the water introduced into the heating cylinder 8 from the water inlet 14 is at high temperature and high pressure as described later.

[0013] At the front end on the downstream side of the heating cylinder 8, a heat preservation block 15 having a heater (not shown) is disposed. A flow path 16 communicating with the inside of the heating cylinder 8 is formed in this heat preservation block 15, and a reaction liquid valve 16a and a molten resin valve 16b are respectively disposed in the flow paths branched on the downstream side of this flow path 16. A pipe 20a is connected to the reaction liquid valve 16a. The downstream side of this pipe 20a is connected to a back pressure valve 3 described later. A pipe 20b is connected to the molten resin valve 16b. The downstream side of this pipe 20b is connected to a molten resin recovery tank (not shown). Note that the reaction liquid valve 16a and the molten resin valve 16b correspond to the "switching valve" referred to in the claims, and the pipe 20b corresponds to the "discharge flow path" referred to in the claims.

[0014] The screw 9 is inserted into the heating cylinder 8 along the longitudinal direction of the heating cylinder 8. The screw 9 is rotated about its axis by a screw drive mechanism (not shown) to convey the fiber reinforced resin R in the cylinder 12 forward. The hydrolysis reaction vessel 2 in which such a screw 9 is disposed in the heating cylinder 8 includes a resin heating and kneading section 21, a resin / water mixing section 22, and a resin / water reaction section 23, from the upstream side to the downstream side of the heating cylinder 8.

[0015] Although not shown in the drawings, the resin heating and kneading section 21 includes a feed section that heats and melts and mixes the fiber reinforced resin R from the hopper 13 and supplies it to the upstream side, a compression section that compresses the molten fiber reinforced resin R from the feed section and supplies it to the upstream side, and a kneading section that kneads the molten fiber reinforced resin R from the compression section while applying a shearing force thereto. Such a resin heating and kneading section 21 forms a seal section S (see FIG. 4) described later made of the molten fiber reinforced resin R. And the water inlet 14 in the present embodiment is formed immediately downstream of the resin heating and kneading section 21.

[0016] The resin / water mixing section 22 mixes the molten fiber reinforced resin R and high-temperature and high-pressure water, and conveys this mixture to the upstream side of the heating cylinder 8. Although not shown in the drawings, the resin / water mixing section 22 includes a feed section that mixes the molten fiber reinforced resin R from the resin heating and kneading section 21 and water under heating and supplies it to the upstream side, a compression section that compresses the mixture of the molten fiber reinforced resin R and water from the feed section and supplies it to the upstream side, and a kneading section that kneads the mixture from the compression section while applying a shearing force thereto.

[0017] The resin / water reaction section 23 conveys the mixture of the molten fiber reinforced resin R and water from the resin / water mixing section 22 to the upstream side, and causes the fiber reinforced resin R and water to react under a predetermined pressure. In the hydrolysis reaction vessel 2 of the present embodiment, a depolymerization reaction occurs in which the amide bond of nylon 6 constituting the fiber reinforced resin R is hydrolyzed. Specifically, the fiber reinforced resin R and water become a reaction solution composed of a hydrolysis product containing a caprolactam monomer and glass fiber. Further, depending on the hydrolysis product, it may also become a depolymerized product accompanied by an intramolecular dehydration reaction.

[0018] Next, the back pressure valve 3 will be described. In this embodiment, the back pressure valve 3 is connected to the downstream side of the piping 20a, as described above. The back pressure valve 3 is also connected to the flush tank 4, which is located downstream of the back pressure valve 3, via piping 20c. In other words, the back pressure valve 3 has an inlet 35a on the piping 20a side for the reaction liquid sent from the hydrolysis reaction vessel 2, and an outlet 35b on the piping 20c side for sending the reaction liquid to the flash tank 4. In Figure 1, reference numeral 34a denotes the indicator pressure port of the back pressure valve 3, and reference numeral 37 denotes a pressure generating means such as a compressor that applies a predetermined indicator pressure to this indicator pressure port 34a.

[0019] Figure 2 is an exploded perspective view of the back pressure valve 3. Figure 3 is a schematic cross-sectional view of the back pressure valve 3. As shown in Figure 2, the back pressure valve 3 has a diaphragm 32 that acts as a pressure regulating valve, maintaining an open state at a predetermined pressure or higher to allow the hydrolysis reaction to proceed in the resin-water reaction section 23 (see Figure 1) of the hydrolysis reaction vessel 2 (see Figure 1). Specifically, the back pressure valve 3 comprises a casing 31 and a diaphragm 32 located inside the casing 31.

[0020] The casing 31 has a casing body 33 and a lid 34. The diaphragm 32 is positioned between the casing body 33 and the lid 34 via an O-ring 37, thereby separating the liquid chamber 38 (see Figure 3) formed on the casing body 33 side from the indicator pressure chamber 39 (see Figure 3) formed on the lid 34 side. In Figure 2, reference numeral 36 denotes a bolt that fastens the casing body 33 and the lid 34, and reference numerals 34c and 34d denotes the reaction liquid flow path, which will be described next.

[0021] As shown in Figure 3, the casing body 33 has a first reaction liquid channel 35c that communicates with the liquid chamber 38 and the reaction liquid inlet 35a, and a second reaction liquid channel 35d that communicates with the liquid chamber 38 and the reaction liquid outlet 35b. Incidentally, when this second reaction fluid channel 35d is closed by the valve portion 32a of the diaphragm 32, the back pressure valve 3 enters the closed state shown in Figure 3. The cover 34 has an indicator pressure port 34a that communicates with the indicator pressure chamber 39.

[0022] In such a back pressure valve 3, an indicator pressure is applied to the indicator pressure port 34a by a pressure generating means 37 (see Figure 1). This indicator pressure can be set to a pressure (predetermined pressure) that allows the hydrolysis reaction to proceed in the resin-water reaction section 23 (see Figure 1) of the hydrolysis reaction vessel 2 (see Figure 1). In other words, as described above, when the pressure upstream of the back pressure valve 3 exceeds a predetermined pressure that allows the hydrolysis reaction to proceed, the valve portion 32a of the diaphragm 32 opens the second reaction liquid flow path 35d and maintains an open state (not shown).

[0023] Furthermore, the back pressure valve 3 is configured so that the control unit C adjusts its opening degree based on the detection signal from the pressure sensor 20a1 installed in the piping 20a. The control procedure by the control unit C (see Figure 1) will be explained later along with the hydrolysis continuous processing method.

[0024] Returning to Figure 1, the flash tank 4 receives the high-temperature, high-pressure reaction liquid sent from the back pressure valve 3 through the piping 20c and then reduces the pressure. In this flash tank 4, the reaction liquid separates into a gas phase containing the vapor and water vapor of the hydrolysis product, caprolactam, and a non-gas phase containing an aqueous solution of caprolactam and glass fibers. The vapor containing caprolactam and water vapor is sent through piping 20d towards the condenser 5. Meanwhile, the liquid containing the aqueous solution of caprolactam and the solid containing glass fibers are sent towards the first dryer 6 via piping 20e having a slurry pump 20e1.

[0025] The condenser 5 sends the caprolactam vapor and the condensate of the vapor containing water vapor, etc., which are sent from the flash tank 4 via piping 20d, to a caprolactam purification system (not shown) via piping 20f. The caprolactam purified in this system is reused as a raw material for nylon 6. The gaseous components separated in the condenser 5 are discharged from the condenser 5 via piping 20g, which has an exhaust pump 20g1.

[0026] In this embodiment, the first dryer 6 and the second dryer 7 are assumed to be dryers having a rotary heating drum, such as a rotary kiln. The first dryer 6 heats a mixture of an aqueous caprolactam solution and glass fibers, which is sent from the flash tank 4 via piping 20e, at atmospheric pressure to a first temperature at least above the boiling point of caprolactam. The first dryer 6 sends out vapor containing caprolactam vapor and water vapor, etc., via piping 20h, which joins piping 20d midway. This vapor passes through the condenser 5, separating into a gaseous component to be discharged and an aqueous caprolactam solution to be purified. The first dryer 6 sends the solid component, which consists of wet glass fibers after drying at the first temperature, to the second dryer 7 via a conveying means 20j such as a belt conveyor.

[0027] The second dryer 7 heats the solid components discharged from the first dryer 6 at a second temperature higher than the first temperature. The second dryer 7 dries the wet solid components to separate the glass fibers. The separated glass fibers are reused as recycled fibers. The gaseous components separated in the second dryer 7 are subjected to bubbling and other cleaning processes as needed before being discharged into the atmosphere.

[0028] <Continuous Hydrolysis Treatment Method> Next, the continuous hydrolysis treatment method of this embodiment will be described while explaining the specific operating conditions of the continuous hydrolysis treatment apparatus 1 (see Figure 1). Figure 4 is a schematic diagram illustrating the operation of the hydrolysis reaction vessel 2 in the continuous hydrolysis processing apparatus 1 shown in Figure 1. The continuous hydrolysis processing method will be described below with reference to Figures 1 to 4.

[0029] The continuous hydrolysis treatment method of this embodiment is characterized by continuously hydrolyzing the fiber-reinforced resin R (a fiber-containing hydrolyzable resin composition) and water by kneading them under heating and pressurizing conditions while conveying them from the upstream side to the downstream side of the heating cylinder 8 using a screw 9 inserted inside the heating cylinder 8. Specifically, this continuous hydrolysis treatment method includes the steps of: introducing the raw material, fiber-reinforced resin R, into the heating cylinder 8; forming a seal portion S (see Figure 4) at a predetermined position in the longitudinal direction of the heating cylinder 8 with the fiber-reinforced resin R melted under heating in the heating cylinder 8 to seal the gap formed between the heating cylinder 8 and the screw 9; and reacting the fiber-reinforced resin R with water by introducing water downstream of the seal portion S in the heating cylinder 8.

[0030] In this embodiment, the fiber-reinforced resin R used as a raw material is assumed to be a nylon 6 matrix resin containing glass fibers, as described above. However, there are no particular limitations on the fiber-reinforced resin R applicable to the present invention, as long as it is hydrolyzable.

[0031] Other matrix resins that constitute the fiber-reinforced resin R include, for example, polyamides such as nylon 66 (PA66), nylon 12 (PA12), nylon 6T (PA6T), nylon 6 / 12 (PA6 / 12), and nylon 6 / 10 (PA6 / 10); polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN); and thermoplastic elastomers (TPC) having hydrolyzable bonds.

[0032] Examples of fibers include carbon fibers, basalt fibers, metal fibers, silicon carbide fibers, aramid fibers, boron fibers, and alumina fibers.

[0033] In the continuous hydrolysis treatment method of this embodiment, first, the target temperature in the resin-water reaction section 23 of the hydrolysis reaction vessel 2 and the indicated pressure of the back pressure valve 3 are set. In this embodiment, which assumes the hydrolysis of nylon 6, the target temperature (reaction temperature) is preferably 320°C or higher and 370°C or lower, with approximately 350°C being the most preferred. By setting the resin-water reaction section 23 to such a reaction temperature, it is possible to improve the productivity of the thermally decomposed nylon 6 while achieving miniaturization of the continuous hydrolysis apparatus 1.

[0034] The indicated pressure of the back pressure valve 3 determines the reaction pressure in the resin-water reaction section 23 during steady-state operation of the continuous hydrolysis treatment apparatus 1. The reaction pressure in the resin-water reaction section 23 is preferably set to at least 4% above the saturation pressure at the target temperature (reaction temperature). Specifically, when the target temperature (reaction temperature) is set within the aforementioned range, the reaction pressure is preferably 16 MPa or more and 20 MPa or less, with approximately 18 MPa being the most preferable. By setting the indicated pressure of the back pressure valve 3 to such a reaction pressure, stable operation of the hydrolysis continuous processing apparatus 1 can be maintained while avoiding boiling in the hydrolysis reaction vessel 2, even when the target temperature (reaction temperature) fluctuates. Furthermore, by setting the reaction pressure in this manner, the seal section S (see Figure 4), described later, can be stably maintained.

[0035] Next, in this continuous hydrolysis treatment method, the temperature of the heat retention block 15 (see Figure 1) of the continuous hydrolysis treatment apparatus 1 is set to a temperature approximately the same as the target temperature (reaction temperature). Then, a predetermined amount of fiber-reinforced resin R, which will be used as the raw material for hydrolysis, is introduced into the heating cylinder 8 via the hopper 13 (see Figure 1). It is desirable that the temperature of the blocks from the block that sends the nylon 6 fiber reinforced material to the water supply position be kept below the melting temperature of nylon 6, approximately 220°C, in order to increase the viscosity of the material seal portion due to the melting of nylon 6 and improve the sealing performance.

[0036] The rotational speed of the screw 9, which is rotated by the motor M (screw drive mechanism) shown in Figure 4, is not particularly limited, but is preferably around 100 to 400 rpm. By equipping the hydrolysis continuous processing apparatus 1 with the screw 9 in the hydrolysis reaction vessel 2, the glass fibers contained in the raw material, with an average fiber length of about 0.3 mm, can be pulverized to an average fiber length of about 0.1 mm. This crushing process prevents fiber entanglement inside the back pressure valve 3 (see Figure 1) and in the slurry pump 20e1 (see Figure 1) during subsequent processes.

[0037] Then, when the raw material introduced from the hopper 13 is transported by the screw 9, as shown in Figure 4, the gap between the screw 9 and the heating cylinder 8 is sealed by the seal section S with the molten raw material (fiber-reinforced resin R (see Figure 1)). Regarding the shape of the screw, it is desirable to appropriately arrange a full flight for transporting the material, a kneading disc to enhance mixing, etc.

[0038] Next, in this continuous hydrolysis treatment method, as shown in Figure 4, high-temperature, high-pressure water is introduced (supplied) downstream of the seal section S. The water introduced is heated to approximately 350°C by heater 14b (see Figure 1) under a pressure of approximately 18 MPa. When the outlet of the hydrolysis reaction vessel 2 is narrowed, the pressure of the mixed solution of molten resin and water filled between the heating cylinder 8 and the screw 9 is maintained at a high level. The volume of the hydrolysis reaction vessel 2 is the gap between the heating cylinder 8 and the screw 9. The residence time t(h) of the mixed solution of molten resin and water in the hydrolysis reaction vessel 2 satisfies the following relationship, where V is the volume of the hydrolysis reaction vessel 2, Q1 / h is the volumetric flow rate of the molten resin raw material, and Q2 / h is the volumetric flow rate of water. Residence time t(h)=V / (Q1+Q2)

[0039] Next, we will explain the temperature range set for the hydrolysis reaction vessel 2. Hydrolysis reactions take longer at lower temperatures and shorter at higher temperatures. In the hydrolysis reaction vessel 2, if the residence time t(h) is to be increased, it is possible to reduce the flow rate of the supplied raw materials or increase the volume V of the hydrolysis reaction vessel 2. However, in practical terms, the hydrolysis continuous processing apparatus 1, which has a large volume and a small processing capacity in the hydrolysis reaction vessel 2, will incur increased initial investment costs. Also, slowing down the rate at which the supplied raw materials are supplied will reduce the productivity of the hydrolyzed products in the hydrolysis continuous processing apparatus 1. Therefore, it is desirable that the reaction temperature in the hydrolysis reaction vessel 2 be 320°C or higher.

[0040] Furthermore, while it is desirable to proceed with the hydrolysis reaction in hydrolysis reaction vessel 2 at a high reaction temperature, setting the reaction temperature in hydrolysis reaction vessel 2 high increases the saturation pressure of the vapor. As a result, when the vapor pressure inside hydrolysis reaction vessel 2 becomes relatively lower than the aforementioned saturation pressure, the internal volume increases rapidly. Therefore, hydrolysis reaction vessel 2 needs to be operated at a pressure higher than the saturation pressure to prevent unstable operation. Accordingly, the reaction pressure in hydrolysis reaction vessel 2 is preferably about 20 MPa or less, and the reaction temperature is preferably 370°C or less. By setting the reaction temperature in this manner, it is possible to obtain high-quality caprolactam that can increase the degree of polymerization when polymerizing nylon 6 from caprolactam.

[0041] Next, we will explain in more detail the pressure range set for the hydrolysis reaction vessel 2. As described above, the pressure in the hydrolysis reaction vessel 2 is set to a pressure higher than the vapor saturation pressure at the set reaction temperature. Table 1 shows the set temperature (°C) of the hydrolysis reaction vessel 2 and the vapor saturation pressure at temperatures within a predetermined range from this set temperature (°C).

[0042] [Table 1]

[0043] Table 1 shows the vapor saturation pressure (MPa) for a temperature range (°C) of ±3°C for set temperatures (°C) of 300°C, 325°C, and 350°C. The ±3°C range takes into account the typical temperature range of 2-3°C in general temperature control. Furthermore, the set pressure (MPa) of the hydrolysis reaction vessel 2 takes into account the operating conditions at a temperature of +3°C. In other words, the set pressure (MPa) of the hydrolysis reaction vessel 2 in this embodiment is set to a pressure range of at least 4% of the vapor saturation pressure at the set temperature. Specifically, as an example, the set pressure (MPa) of the hydrolysis reaction vessel 2 can be set to 18 MPa, which is a marginal value compared to the vapor saturation pressure of 17.154 MPa (4% increase when the saturation pressure is set to 1) at a temperature setting of 350°C (°C), as shown in Table 1.

[0044] The reaction time (residence time) in the hydrolysis reaction vessel 2 can be, for example, at least 20 minutes if the set temperature is 320°C, at least 10 minutes if it is 370°C, and at least 15 minutes if it is 350°C.

[0045] The hydrochloric acid concentration can be between 10% and 80%. The hydrochloric acid concentration is expressed by the following formula. Added water concentration X(%)=100·W2 / (W1+W2) [However, in the above formula, W1 is the raw material supply rate (kg / h), and W2 is the water supply rate (kg / h)] Furthermore, by setting the water concentration to 10% or higher, more uniform contact mixing of the raw material and water can be achieved, thereby improving the yield of caprolactam. Also, by setting the water concentration to 80% or lower, the concentration of caprolactam in the caprolactam solution produced in subsequent processes can be maintained at a relatively high level, thereby reducing the energy required to concentrate caprolactam during purification. Incidentally, in this embodiment of the continuous hydrolysis treatment method, a water concentration of approximately 50% is assumed.

[0046] On the other hand, in the continuous hydrolysis processing apparatus 1 immediately after startup, the temperature of the molten resin that reaches the heat retention block 15 (see Figure 1) located upstream of the heating cylinder 8 is low, and its viscosity is also high. Therefore, the continuous hydrolysis treatment method in this embodiment includes a pipe 20b (see Figure 1) which serves as a discharge channel for separately recovering molten resin until it transitions to steady-state operation. Until the continuous hydrolysis processing apparatus 1 is switched to steady-state operation, the reaction liquid valve 16a is closed and the molten resin valve 16b is open. As a result, the highly viscous molten resin is recovered through pipe 20b.

[0047] In this continuous hydrolysis process, the molten resin valve 16b is gradually closed. As a result, the pressure in the resin-water reaction section 23 (see Figure 1) of the hydrolysis reaction vessel 2 gradually increases as the screw 9 transports the molten fiber-reinforced resin R upstream. When the temperature and pressure in the resin-water reaction section 23 reach the predetermined pressure and target temperature (reaction temperature) described above, the continuous hydrolysis processing device 1 transitions to steady-state operation.

[0048] Then, when the hydrolysis continuous processing apparatus 1 transitions to steady-state operation, the reaction liquid valve 16 is opened. The reaction liquid containing the hydrolysis product is sent to the flash tank 4 via piping 20a and piping 20c, which have back pressure valves 3.

[0049] In this case, the back pressure valve 3 maintains a predetermined pressure in the resin-water reaction section 23 according to a preset indicative pressure. Furthermore, the back pressure valve 3 is configured to increase its opening when the pressure between the hydrolysis reaction vessel 2 and the back pressure valve 3 (pressure in the piping 20a) reaches a preset second pressure (pressure threshold) that is higher than a predetermined pressure (first pressure) that allows the hydrolysis reaction in the hydrolysis reaction vessel 2 to proceed.

[0050] Specifically, based on the detection signal from the pressure sensor 20a1 located on the piping 20a, the control unit C increases the opening degree of the back pressure valve 3 when the pressure reaches a preset second pressure (pressure threshold) that is higher than a predetermined pressure (first pressure). Incidentally, the second pressure (pressure threshold) is intended to account for the case where glass fibers inadvertently clog the back pressure valve 3. The control unit C clears the blockage in the back pressure valve 3 by increasing the opening degree of the back pressure valve 3 in response to the second pressure (pressure threshold). Furthermore, if the control unit C determines, based on the detection signal from the pressure sensor 20a1, that the pressure in the piping 20a has fallen below the second pressure (pressure threshold), it stops sending commands to the back pressure valve 3. As a result, the back pressure valve 3 returns to the open state according to the initial instructed pressure.

[0051] In this continuous hydrolysis treatment method, the caprolactam contained in the gas phase in the flash tank 4 is recovered in the condenser 5, as described above. The caprolactam contained in the non-gas phase (aqueous phase) in the flash tank 4 is recovered via the first dryer 6 and the condenser 5, as described above. Furthermore, the glass fibers contained in the non-gas phase (aqueous phase) in the flash tank 4 are recovered via the first dryer 6 and the second dryer 7.

[0052] <Effects and Effects> Next, the effects and benefits of the resin molded product manufacturing apparatus 1 and the resin molded product manufacturing method according to this embodiment will be described. In the hydrolysis continuous processing apparatus 1 of this embodiment, unlike conventional batch-processing hydrolysis apparatuses (see, for example, Patent Document 1), hydrolysis is carried out continuously in the hydrolysis reaction vessel 2 under heating and pressurizing conditions. This enables the hydrolysis continuous processing apparatus 1 to process large quantities of fiber-reinforced resin R (hydrolyzable resin composition) through continuous processing. Furthermore, unlike conventional batch hydrolysis apparatuses, the continuous hydrolysis apparatus 1 can perform hydrolysis of hydrolyzable resin compositions using only water without the use of a catalyst. In addition, depending on the hydrolyzable resin composition, the continuous hydrolysis apparatus 1 can also perform a dehydration reaction after hydrolysis.

[0053] Furthermore, unlike conventional batch-processing hydrolysis apparatuses, the continuous hydrolysis apparatus 1 of this embodiment does not require increasing the capacity or wall thickness of the container in order to secure the processing volume per unit time. As a result, the continuous hydrolysis apparatus 1 can be made smaller than conventional apparatuses. Furthermore, according to the hydrolysis continuous processing apparatus 1 of this embodiment, the screws 9 of the hydrolysis reaction vessel 2 can crush the fibers contained in the fiber-reinforced resin R (hydrolyzable resin composition). This effectively prevents clogging by fibers downstream. Furthermore, according to the hydrolysis continuous processing apparatus 1 of this embodiment, the back pressure can be released by the back pressure valve 3, which has an adjustable opening degree, thereby suppressing the accumulation of solid materials such as glass fibers in the hydrolysis reaction vessel 2 and the back pressure valve 3.

[0054] Furthermore, the continuous hydrolysis apparatus 1 of this embodiment can adjust the opening degree according to the indicated pressure using a back pressure valve 3 having a diaphragm 32 (pressure regulating valve). Specifically, the diaphragm 32 (pressure regulating valve) adjusts the flow path cross-sectional area according to the indicated pressure and discharges solid materials such as glass fibers when the cross-sectional area becomes larger. As a result, the continuous hydrolysis apparatus 1 can more reliably suppress the accumulation of solid materials such as glass fibers in the hydrolysis reaction vessel 2 and the back pressure valve 3.

[0055] Furthermore, in this embodiment of the continuous hydrolysis apparatus 1, when the pressure between the hydrolysis reaction vessel 2 and the back pressure valve 3 reaches a preset second pressure that is higher than the first pressure that allows the hydrolysis reaction in the hydrolysis reaction vessel 2 to proceed, the back pressure valve 3 increases its opening. This continuous hydrolysis apparatus 1 can more reliably suppress the accumulation of solids such as glass fibers.

[0056] Furthermore, the hydrolysis continuous processing apparatus 1 of this embodiment is equipped with a switching valve consisting of a reaction liquid valve 16a and a molten resin valve 16b between the hydrolysis reaction vessel 2 and the back pressure valve 3. With this continuous hydrolysis apparatus 1, unreacted material sent from the hydrolysis reaction vessel 2 can be discharged during the time elapsed from startup until steady-state operation is reached. This prevents the accumulation and clogging of unreacted material in the back pressure valve 3. Furthermore, since this continuous hydrolysis apparatus 1 can discharge unreacted material sent from the hydrolysis reaction vessel 2, the purity of the recovered hydrolysis product can be increased.

[0057] Furthermore, the continuous hydrolysis treatment method of this embodiment includes a step of reacting the fiber-reinforced resin R (hydrolyzable resin composition) with water by introducing water downstream of the seal portion S in the heating cylinder 8. This continuous hydrolysis treatment method allows for an effective reaction between the fiber-reinforced resin R (hydrolyzable resin composition) and water near the upstream end of the heating cylinder 8. This makes it possible to secure a longer section of the resin-water reaction part 23 in the hydrolysis reaction vessel 2, thereby further increasing the yield of the recovered hydrolysis product.

[0058] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be implemented in various forms. [Explanation of symbols]

[0059] 1. Continuous hydrolysis treatment apparatus 2 Hydrolysis reaction vessel 3. Back pressure valve 8 Heating tube 9 Screw 13. Hopper (introduction section for fiber-containing hydrolyzable resin composition) 14. Water inlet (water entry point) 16a Reaction solution valve (switching valve) 16b Valve for molten resin (switching valve) 20b Discharge channel 32. Diaphragm (pressure regulating valve) R Fiber-reinforced resin (hydrolyzable resin composition containing fibers)

Claims

1. A heating cylinder having an introduction section for a fiber-containing hydrolyzable resin composition and an introduction section for water, A hydrolysis reaction vessel having a screw inserted into the heating cylinder and transporting the hydrolyzable resin composition and the water downstream within the heating cylinder while mixing them, A pressure regulating valve is provided downstream of the hydrolysis reaction vessel, which sets the pressure in the hydrolysis reaction vessel to a predetermined pressure for the hydrolysis reaction to proceed, while allowing the hydrolysis product and fibers to flow downstream. A sealing portion formed from the molten hydrolyzable resin composition, positioned upstream of the water inlet in the longitudinal direction of the heating cylinder, and sealing the gap between the heating cylinder and the screw, Equipped with, The pressure regulating valve is a diaphragm that adjusts the flow path cross-sectional area according to the indicated pressure. A continuous hydrolysis apparatus characterized in that when the pressure between the hydrolysis reaction vessel and the pressure regulating valve reaches a preset second pressure that is higher than a first pressure that allows the hydrolysis reaction in the hydrolysis reaction vessel to proceed, the pressure regulating valve increases its opening.

2. A heating cylinder having an introduction section for a fiber-containing hydrolyzable resin composition and an introduction section for water, A hydrolysis reaction vessel having a screw inserted into the heating cylinder and transporting the hydrolyzable resin composition and the water downstream within the heating cylinder while mixing them, A pressure regulating valve is provided downstream of the hydrolysis reaction vessel, which sets the pressure in the hydrolysis reaction vessel to a predetermined pressure for the hydrolysis reaction to proceed, while allowing the hydrolysis product and fibers to flow downstream. A sealing portion formed from the molten hydrolyzable resin composition, positioned upstream of the water inlet in the longitudinal direction of the heating cylinder, and sealing the gap between the heating cylinder and the screw, Equipped with, When the pressure between the hydrolysis reaction vessel and the pressure regulating valve reaches a preset second pressure that is higher than the first pressure that allows the hydrolysis reaction in the hydrolysis reaction vessel to proceed, the pressure regulating valve increases its opening. The continuous hydrolysis apparatus according to claim 1, wherein the fiber-containing hydrolyzable resin composition is a nylon 6 fiber-reinforced material as a raw material, and the temperature of the blocks from the block that supplies the nylon 6 fiber-reinforced material to the water supply position is set to 220°C or lower, which is the melting temperature of nylon 6.

3. The continuous hydrolysis apparatus according to claim 1, characterized in that the pressure regulating valve maintains an open state at a predetermined pressure or higher.

4. The continuous hydrolysis apparatus according to any one of claims 1 to 3, characterized in that it has a switching valve between the hydrolysis reaction vessel and the pressure regulating valve, and a discharge channel leading from the switching valve to the outside of the apparatus.

5. The continuous hydrolysis apparatus according to claim 1, further comprising a flash tank for reducing the pressure of the high-temperature, high-pressure hydrolysis product flowing from the pressure regulating valve and for vaporizing and recovering the hydrolysis product.

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