JP4011474B2 - Waste disposal method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating waste such as electric wires and cables.
[0002]
[Prior art]
Cross-linked polyolefins such as cross-linked polyethylene and cross-linked polypropylene, which are widely used as insulating materials for electric wires and cables, have been said to be difficult to recycle as plastic raw materials, like vulcanized rubber and thermosetting resins. However, recently, a technology for decomposing various polymer resources into reusable low to medium molecular compounds using supercritical or subcritical water has been devised, and it can be expected to be applied to crosslinked polyolefins. Has been.
[0003]
Under such circumstances, the present inventors have developed a method of decrosslinking a crosslinked polyolefin and regenerating it into an uncrosslinked polyolefin, and filed an application earlier (for example, see Patent Document 1). This method has the advantage that a post-recovery polymerization step is unnecessary and it can be used as a plastic material as it is.
[0004]
[Patent Document 1]
JP 2001-323022 A
[0005]
[Problems to be solved by the invention]
However, the cross-linked polyolefin recovered from the wire / cable waste is rarely single, and in many cases is recovered in a state where it is mixed with or integrated with carbon-containing polyolefin. That is, for example, CV cables (cross-linked polyethylene insulated vinyl sheathed cables) that are frequently used as power cables are semiconductive polyolefins (inner layers (or inner and outer layers) of an insulating layer made of cross-linked polyethylene blended with conductive carbon black ( Usually, an internal semiconductive layer (or an internal semiconductive layer and an external semiconductive layer) made of an ethylene / vinyl acetate copolymer is provided, and the insulator layer and the semiconductive layer are usually in close contact with each other. Therefore, the crosslinked polyethylene is recovered as a composite with the semiconductive polyolefin. For this reason, in order to recover uncrosslinked polyethylene from the crosslinked polyethylene of electric wire / cable waste, the semiconductive polyolefin must first be separated. However, it is very difficult to separate the cross-linked polyethylene and the semiconductive polyolefin thus combined, and it is not easy to separate them even if they are not combined and simply mixed.
[0006]
Under such circumstances, a technology that can selectively decompose only the cross-linked polyolefin and recover it as an uncross-linked polyolefin without separating the semi-conductive polyolefin from the waste containing the cross-linked polyolefin and the semi-conductive polyolefin. Is required.
[0007]
And, when recovering unvulcanized rubber from a two-layer rubber tire having a rubber layer containing reinforcing carbon on the surface layer, the same applies not only to crosslinked polyolefin but also to other crosslinked plastic and vulcanized rubber. There is a request.
[0008]
The present invention has been made in response to such a conventional situation, and only a cross-linked / vulcanized polymer compound is selectively selected from a waste composed of a cross-linked / vulcanized polymer compound and a polymer compound containing carbon. An object of the present invention is to provide a waste treatment method that can be recovered as an uncrosslinked or unvulcanized polymer compound that can be decrosslinked or devulcanized and used as it is as a polymer material.
[0009]
[Means for Solving the Problems]
  To achieve the above objective,Invention of the present applicationThe waste disposal method isA waste made of a crosslinked polyolefin and a carbon-containing polyolefin is accommodated in the inner container of a double-structured container consisting of a coarse mesh-shaped inner container and a fine mesh-shaped outer container, and introduced into the preloading chamber. The preload chamber is pressurized with water, and the container containing the waste is 200 ℃ ~ 700 ℃, pressure 0.1MPa ~ 100MPa Is transferred to a reaction chamber in which a supercritical water or subcritical water region is formed and held for a required time to decompose the crosslinked polyolefin to produce an uncrosslinked polyolefin, and a container containing the uncrosslinked polyolefin is The uncrosslinked polyolefin that has been transferred to the outer container by being transferred to the decompression chamber that has been pressurized in advance, decompressing the decompression chamber, and discharging the container from the decompression chamber.It is characterized by collecting.
[0012]
  According to the present invention, a cross-linked polyolefin and a carbon-containing polyolefinFrom waste consisting ofCarbon-containing polyolefinHighly reusable without separationUncrosslinked polyolefinCan be recovered. Moreover, according to the present invention, the container can be introduced into the reaction chamber without lowering the temperature and pressure of the reaction chamber, and can be discharged to the outside, so that waste can be efficiently processed. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a diagram schematically showing a configuration of a processing apparatus used in the first embodiment of the present invention.
[0018]
As shown in FIG. 1, this apparatus has a pressure-resistant reaction vessel 1 equipped with an electric furnace 1 a, a pure water tank 2 containing pure water, and pure water from the pure water tank 2 to send the pure water into the pressure-resistant reaction vessel 1. And a deaeration pipe 5 in which a pressure reducing valve 4 for adjusting the pressure in the pressure-resistant reaction vessel 1 is inserted. Further, a line heater 7 is attached to the pipe 6 connecting the pump 3 and the pressure resistant reactor 1, and a temperature measuring thermocouple 8 is attached to the pressure resistant reactor 1.
[0019]
As shown in an enlarged view in FIG. 2, the pressure resistant reaction container 1 includes a container main body 10 and a cap 11, and a mesh-like tray 12 is held in the container main body 10. Note that the tray 12 is preferably formed of a material such as ceramic that does not decompose with supercritical water or the like and does not make it difficult to control the decomposition reaction.
[0020]
In order to treat the waste composed of the crosslinked or vulcanized polymer compound (a) and the carbon-containing polymer compound (b) using such an apparatus, first, the waste is disposed on the ceramic tray 12 of the pressure resistant reactor 1. The object is placed directly or in a mesh-like container 13 similar to the tray 12. It is preferable to make the size and shape of the waste as uniform as possible by cutting in advance.
[0021]
After the pressure-resistant reaction container 1 is sealed with the cap 11, pure water heated by the line heater 7 is continuously supplied from the pure water tank 2 into the pressure-resistant reaction container 1, and the pressure-resistant reaction container 1 is heated to The temperature and pressure are set to ranges as described later. As the temperature or the temperature and pressure increase, the selective decrosslinking or devulcanization of the crosslinked or vulcanized polymer compound (a) proceeds (the carbon-containing polymer compound (b) is not decomposed) and is not crosslinked. Alternatively, an unvulcanized polymer compound is produced.
[0022]
Thereafter, the heating is stopped and the inside of the pressure-resistant reaction vessel 1 is returned to normal temperature and pressure. The uncrosslinked or unvulcanized polymer compound produced in this process falls downward through the mesh of the container 13 and the tray 12 and accumulates at the bottom of the pressure resistant reaction container 1, so that the pressure resistant reaction container 1 is opened. ,to recover.
[0023]
In such a method, the carbon-containing polymer compound (b) is not decomposed, and only the crosslinked or vulcanized polymer compound (a) is selectively decomposed to produce an uncrosslinked or unvulcanized polymer compound. Therefore, the carbon-containing polymer compound (b) is not separated or removed in advance from the waste comprising the crosslinked or vulcanized polymer compound (a) and the carbon-containing polymer compound (b). Unvulcanized polymer compounds can be recovered.
[0024]
In the above method, the temperature and pressure in the pressure resistant reactor 1 when producing an uncrosslinked or unvulcanized polymer compound are preferably in the range of 200 ° C. to 700 ° C. and 0.1 MPa to 100 MPa, respectively. More preferably, the range is from C to 500C and from 0.1 MPa to 50 MPa. If the reaction temperature is lower than 200 ° C, the depolymerization or devulcanization of the polymer compound may not proceed sufficiently. If the reaction temperature is higher than 700 ° C, the crosslinking point (or vulcanization point) of the crosslinked polymer compound There is a risk that decomposition will proceed and the molecular weight may be lowered even in other parts. In addition, the carbon-containing polymer compound (b) may be decomposed. On the other hand, when the reaction pressure is lower than 0.1 MPa, the decomposition rate of the cross-linked or vulcanized polymer compound (a) is decreased, which is inefficient. On the other hand, when the reaction pressure is higher than 100 MPa, the same problem as when the reaction temperature is higher than 700 ° C. may occur. The reaction time varies depending on the size and amount of waste, reaction temperature, reaction pressure, etc., but is usually in the range of 1 second to 60 minutes.
[0025]
In addition, since the generated uncrosslinked or unvulcanized polymer compound may be decomposed with time and may have a low molecular weight, it may be generated by attaching a pressure release valve to the lower part of the pressure-resistant reaction vessel 1. Thereafter, it is desirable to quickly drop it onto the bottom of the pressure resistant reactor 1 and collect it.
[0026]
FIG. 3 is a diagram schematically showing a configuration of a processing apparatus used in the second embodiment of the present invention.
[0027]
In FIG. 3, reference numeral 20 denotes a cylindrical processing tower. The processing tower 20 has, in order from the top, an opening for introducing waste or its decomposition product at the upper end, and waste at the lower end. Alternatively, a preload chamber 21, a reaction chamber 22, and a decompression chamber 23 having a discharge port for discharging decomposition products and the like are provided. The discharge port of the preload chamber 21 and the introduction port of the reaction chamber 22, the discharge port of the reaction chamber 22 and the introduction port of the decompression chamber 23 are connected via common valves 24 a and 24 b, respectively. The valves 24c and 24d are also connected to the discharge port of the decompression chamber 23, respectively. A receiver 25 for receiving a decomposition product of the waste discharged from the discharge port of the decompression chamber 23 is disposed below the processing tower 20.
[0028]
The reaction chamber 22 is roughly divided into three equal parts, and a preheating part 26, a reaction part 27, and a cooling part 28 are formed in order from the top. That is, a heater 29 is disposed at the lower part of the preheating unit 26 and the outer periphery of the reaction unit 27, and a cooling pipe 30 is provided on the outer periphery of the cooling unit 28. The cooling pipe 30 constitutes a part of a pipe 31 for supplying pure water into the reaction chamber 22. The pure water is supplied from a pure water tank 32 containing pure water by a pump 33. It passes through the cooling pipe 30 and is supplied into the reaction chamber 22 through a pure water supply port that is open at substantially the middle part of the preheating part 26. A preheater 34 for preheating pure water is provided near the pure water supply port of the pipe 31.
[0029]
Further, a pipe 35 for discharging heated and pressurized pure water in the reaction chamber 22, gas or liquid generated by the processing, and the like is connected to the lower portion of the reaction chamber 22. In the figure, 36 is a pressure reducing valve.
[0030]
The preload chamber 21 and the decompression chamber 23 are for maintaining the internal pressure when the waste is introduced into the reaction chamber 22 and the decomposition products of the waste are discharged. The internal pressure is increased and reduced by pure water having a low temperature of about 40 ° C. That is, in the preload chamber 21 and the decompression chamber 23, pipes 39a and 39b for supplying pure water from a pure water tank 37 containing pure water by a pump 38, and a pressure reducing valve 36 for discharging pure water. The piping 40 and 41 provided with are connected. Note that pure water is also supplied to the preload chamber 21 from a branch pipe 31 a branched from the pipe 31.
[0031]
Furthermore, in the preload chamber 21 and the three regions constituting the reaction chamber 22, that is, the preheating unit 26, the reaction unit 27, the cooling unit 28, and the decompression chamber 23, waste or decomposition products thereof are provided. Holding means 42a, 42b, 42c, 42d, and 42e are provided for holding them in these chambers or areas for a required time. Among these, the holding means 42a, 42d, and 42e located in the preload chamber 21, the cooling section 28 of the reaction chamber 22, and the decompression chamber 23 are disposed of the waste or decomposition products thereof in the valves 24a, 24b, and 24d. It also has the role of preventing the function from being impaired by direct contact.
[0032]
In order to treat the waste comprising the crosslinked or vulcanized polymer compound (a) and the carbon-containing polymer compound (b) using such an apparatus, first, a valve 24c connected to the inlet of the preload chamber 21 is used. Is opened, the other valves 24a, 24b, 24d are closed, and the reaction chamber 22 and the decompression chamber 23 are sealed. Next, the heater 29 is energized, the pump 33 is started, pure water heated by the preheater 34 from the pure water tank 32 is supplied to the reaction chamber 22, and the preheating unit 26, A reaction unit 27 and a cooling unit 28 are formed. Further, the pump 38 is activated to supply pure water having a low temperature of about room temperature to about 40 ° C. from the pure water tank 37, and the internal pressure of the decompression chamber 23 is increased to the same pressure as the internal pressure of the reaction chamber 22.
[0033]
The internal temperature and internal pressure of the reaction section 27 are preferably adjusted to be in the range of 200 ° C. to 700 ° C. and 0.1 MPa to 100 MPa, and more preferably in the range of 200 ° C. to 500 ° C. and 0.1 MPa to 50 MPa, respectively. It is. If the temperature is lower than 200 ° C, the polymer compound may not be sufficiently decrosslinked or devulcanized. If it is higher than 700 ° C, the portion other than the crosslinking point (or vulcanization point) of the crosslinked polymer compound However, there is a risk that decomposition proceeds and the molecular weight decreases. In addition, the carbon-containing polymer compound (b) may be decomposed. On the other hand, when the pressure is lower than 0.1 MPa, the decomposition rate of the cross-linked or vulcanized polymer compound (a) is decreased, which is inefficient. On the other hand, if the pressure is higher than 100 MPa, the same problem as when the reaction temperature is higher than 700 ° C. may occur.
[0034]
In this state, waste is put into the preload chamber 21. In the present invention, the waste is roughly mesh-shaped inner container 51 and a fine-mesh mesh as shown schematically in FIG. A double-structured container 50 comprising an outer container 52, that is, an inner container 51 capable of holding waste but discharging its decomposition products (uncrosslinked or unvulcanized polymer compound), and the inner container A space portion is formed between the pre-load chamber 21 and the space product is accommodated in a container composed of an outer container 52 capable of sufficiently holding the decomposition product discharged from the inner container 51. The container 50 is preferably formed of a material such as ceramic that does not decompose with supercritical water or the like and does not make it difficult to control the decomposition reaction, like the tray 12 described above.
[0035]
When the waste is charged, the preload chamber 21 is at normal temperature and pressure.
The waste charged in the container 50 is held in the preload chamber 21 at a position separated from the valve 24a by the holding means 42a.
After the waste is charged, the valve 24c is closed and the pump 38 is activated to supply pure water having a low temperature of about room temperature to about 40 ° C. from the pure water tank 37 to increase the internal pressure of the preload chamber 21. When the internal pressure of the preload chamber 21 becomes substantially the same as the internal pressure of the reaction chamber 22, the valve 24a is opened and the holding by the holding means 42a is released.
[0036]
The container 50 containing the waste falls by its own weight from the preload chamber 21 into the reaction chamber 22, and is temporarily held in the preheating section 26 by the holding means 42b and preheated. Thereafter, the holding by the holding unit 42b is released, and the container 50 containing the waste is dropped into the reaction unit 27 and held by the holding unit 42c. During this time, the crosslinked or vulcanized polymer compound (a) in the container 50 is decrosslinked or devulcanized (the carbon-containing polymer compound (b) is not decomposed), and the uncrosslinked or unvulcanized polymer. A compound is produced. The produced uncrosslinked or unvulcanized polymer compound is eluted from the inner container 51 of the container 50 to the outer container 52.
[0037]
Next, the holding by the holding unit 42 c is released, and the container 50 is dropped onto the cooling unit 28 and held by the holding unit 42. When the container 50 is cooled to a temperature close to room temperature in the cooling unit 28, the valve 24b is opened, the holding by the holding means 42d is opened, and the pressure in the decompression chamber 23 previously set to the same pressure as the internal pressure of the reaction chamber 22 Is dropped by its own weight and is held by the holding means 42e. Further, when the container 50 falls into the decompression chamber 23, the valve 24b is closed, the pure water in the decompression chamber 23 is discharged and decompressed, and the valve 24d is opened when the internal pressure of the decompression chamber 23 reaches normal pressure, The holding by the holding means 42e is released, dropped into the receiver 25, and collected.
[0038]
In the outer container 52 of the recovered container 50, the eluted uncrosslinked or unvulcanized polymer compound is collected, and this is recovered.
[0039]
On the other hand, the preload chamber 21 is depressurized by closing the valve 24a after the container 50 containing the waste falls into the reaction chamber 22. When the internal pressure becomes almost normal pressure, the valve 24c is opened and the above operation is repeated.
[0040]
In this way, by sequentially putting the waste into the preload chamber 21 and repeating the above operation, the waste is efficiently treated, and the crosslinked or unvulcanized polymer compound can be recovered.
[0041]
In such a method, it is not necessary to separate and remove the carbon-containing polymer compound (b) in advance, and waste is introduced into the reaction chamber 22 and discharged while maintaining the temperature and pressure in the reaction chamber 22. Therefore, the uncrosslinked or unvulcanized polymer compound can be recovered more efficiently from the waste comprising the crosslinked or vulcanized polymer compound (a) and the carbon-containing polymer compound (b). .
[0042]
In this embodiment, the time for holding the container 50 in the reaction unit 27 of the reaction chamber 22 varies depending on the size and amount of waste, the temperature and pressure in the reaction unit 27, etc., but usually 1 second to 60 minutes. Range.
[0043]
FIG. 5 is a diagram schematically showing a configuration of a processing apparatus used in the third embodiment of the present invention.
[0044]
As shown in FIG. 5, this apparatus includes a pressure-resistant reaction vessel 60 provided with an electric furnace 60a, a pure water tank 61 containing pure water, a solvent tank 62 containing an organic solvent such as xylene and toluene, Pumps 63 and 64 for feeding pure water and an organic solvent from the pure water tank 61 and the solvent tank 62 to the pressure-resistant reaction vessel 60 respectively, and heated and pressurized pure water and organic solvents in the pressure-resistant reaction vessel 60, treatment And a pipe 65 for discharging the components generated by the above. The pipe 65 branches in the middle, a pressure reducing valve 66 is connected to one branch pipe 65a, the other branch pipe 65b is connected to a solid-liquid separator 67, and further, this solid-liquid separator 67 includes: A pipe 68 in which a pressure reducing valve 66 is inserted is connected. A line heater 69 is attached to the pipe 65 and the branch pipe 65b connecting the pressure-resistant reaction vessel 60 and the solid-liquid separator 67. Further, the pressure-resistant reaction vessel 60 is provided with a thermocouple 70 for temperature measurement. It is installed.
[0045]
In order to treat the waste composed of the crosslinked or vulcanized polymer compound (a) and the carbon-containing polymer compound (b) using such an apparatus, first, the waste is put into the pressure resistant reactor 60. It is preferable to make the size and shape of the waste as uniform as possible by cutting in advance.
[0046]
After sealing the pressure-resistant reaction vessel 60, pure water is continuously supplied from the pure water tank 61 into the pressure-resistant reaction vessel 60, and the pressure-resistant reaction vessel 60 is heated so that the internal temperature and pressure are within the ranges described later. And As the temperature or the temperature and pressure increase, the selective decrosslinking or devulcanization of the crosslinked or vulcanized polymer compound (a) proceeds (the carbon-containing polymer compound (b) is not decomposed) and is not crosslinked. Alternatively, an unvulcanized polymer compound is produced.
[0047]
Then, heating is stopped and the pressure-resistant reaction container 1 is returned to normal pressure. When the temperature in the pressure-resistant reaction vessel 60 is cooled to around 150 ° C., the introduction of pure water is stopped and the valve inserted in the branch pipe 65a is closed. The solvent is continuously supplied, the inside of the pressure-resistant reaction vessel 60 is replaced with an organic solvent, and the pressure of the pressure-resistant reaction vessel 60 is increased to 0.1 MPa to 5 MPa. By continuing the supply of the organic solvent as it is, the produced uncrosslinked or unvulcanized polymer compound is extracted by the organic solvent, separated from the organic solvent by the solid-liquid separator 67 and recovered.
[0048]
In such a method, an uncrosslinked structure is obtained without previously separating and removing the carbon-containing polymer compound (b) from the waste comprising the crosslinked or vulcanized polymer compound (a) and the carbon-containing polymer compound (b). Alternatively, the unvulcanized polymer compound can be recovered.
[0049]
In the above method, the temperature and pressure in the pressure-resistant reaction vessel 60 when the uncrosslinked or unvulcanized polymer compound is produced are preferably in the range of 200 ° C. to 700 ° C. and 0.1 MPa to 100 MPa, respectively. More preferably, the range is from C to 500C and from 0.1 MPa to 50 MPa. If the reaction temperature is lower than 200 ° C, the depolymerization or devulcanization of the polymer compound may not proceed sufficiently. If the reaction temperature is higher than 700 ° C, the crosslinking point (or vulcanization point) of the crosslinked polymer compound There is a risk that decomposition will proceed and the molecular weight may be lowered even in other parts. In addition, the carbon-containing polymer compound (b) may be decomposed. On the other hand, when the reaction pressure is lower than 0.1 MPa, the decomposition rate of the cross-linked or vulcanized polymer compound (a) is decreased, which is inefficient. On the other hand, when the reaction pressure is higher than 100 MPa, the same problem as when the reaction temperature is higher than 700 ° C. may occur. The reaction time varies depending on the size and amount of waste, reaction temperature, reaction pressure, etc., but is usually in the range of 1 second to 60 minutes.
[0050]
The present invention is useful for the treatment of waste made of crosslinked polyolefin and non-crosslinked polyolefin containing carbon, and waste made of various vulcanized rubber and vulcanized rubber containing carbon. A particularly remarkable effect is observed when applied to the treatment of waste containing a polymer compound having a carbon content of 0.01% by weight or more, preferably 1% by weight, more preferably 5% by weight or more.
[0051]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.
[0052]
Example 1
From the same material as the internal semiconductive layer made of an ethylene / vinyl acetate copolymer containing 30% by weight of conductive carbon on the conductor, the insulator layer made of cross-linked polyethylene (gel fraction 80%), and the internal semiconductive layer A 6 kV CV cable coated with an outer semiconductive layer was cut to a length of 2 cm, the inner conductor was removed, and the product was divided into two vertically and processed using the processing apparatus shown in FIG.
[0053]
First, the sample was placed on a zirconia tray (mesh size 1 cm □) 12 fixed at a position 3 cm from the bottom of the pressure-resistant reaction vessel (inner diameter 60 mm, depth 60 mm, effective internal volume 170 ml) 1 and sealed. Pure water degassed from the pure water tank 2 was fed into the pressure resistant reaction vessel 1 to maintain the pressure in the pressure resistant reaction vessel 1 at 25 MPa. When the pressure was stabilized, the temperature in the pressure resistant reactor 1 was raised to 380 ° C. and held for 1 minute (reaction time: 1 minute). Thereafter, while maintaining the temperature of 380 ° C., the introduction of pure water is stopped, the internal pressure of the pressure resistant reactor 1 is returned to normal pressure, and the temperature is also cooled to normal temperature. Lump was collected.
An infrared spectroscopic analysis of the recovered product confirmed that it was polyethylene.
[0054]
Example 2
From the same material as the internal semiconductive layer made of an ethylene / vinyl acetate copolymer containing 30% by weight of conductive carbon on the conductor, the insulator layer made of cross-linked polyethylene (gel fraction 80%), and the internal semiconductive layer A 6 kV CV cable coated with an outer semiconductive layer was cut to a length of 5 cm, the inner conductor was removed, and a sample obtained by dividing the length into 1/4 was used as a sample.
[0055]
This sample is placed in a cylindrical inner container 51 (outer diameter 15 mm, height 150 mm, effective internal volume 26 ml, mesh size 0.5 cm □) made of zirconia mesh, and this container is made of zirconia mesh. The cylindrical outer container 52 (outer diameter 30 mm, height 300 mm, effective internal volume 212 ml, mesh size 0.01 cm □) was accommodated and fixed in an intermediate position and placed in the preload chamber 21 of the apparatus shown in FIG.
[0056]
After the charging, the valve 24c at the top of the preload chamber 21 was closed, and the internal pressure in the preload chamber 21 was increased with normal temperature pure water. When the internal pressure reaches 50 MPa, the valve 24a between the preloading chamber 21 and the reaction chamber 22 is opened, and the preheating section 26 of the reaction chamber 22 that has been previously formed at 300 ° C. and 50 MPa by introducing pure water. The weight was dropped and held for 5 minutes.
[0057]
Next, the weight was dropped into the reaction unit 27 that had been similarly formed at 380 ° C. and 50 MPa, held for 1 minute, then dropped into the cooling unit 28 of the reaction chamber 22 and held for 5 minutes.
[0058]
Thereafter, the valve 24b at the bottom of the reaction chamber 22 is opened, and the dead pressure is dropped to the decompression chamber 23 whose internal pressure has been previously increased to 50 MPa by introduction of pure water, and the internal pressure of the decompression chamber 23 is returned to normal pressure. The valve 24d was opened, the container 50 was dropped into the receiver 25, and a white lump between the outer container 52 and the inner container 51 was collected.
This recovered material was confirmed to be polyethylene by infrared spectroscopic analysis and infrared spectroscopic analysis.
[0059]
Example 3
A sample similar to Example 1 was processed using the processing apparatus shown in FIG.
First, a sample is put into a pressure resistant reaction vessel (inner diameter 60 mm, depth 60 mm, effective internal volume 170 ml) 60 and sealed, and then degassed pure water tank 61 is fed into the pressure resistant reaction vessel 60 to withstand pressure. The pressure in the reaction vessel 60 was maintained at 25 MPa. When the pressure was stabilized, the temperature in the pressure-resistant reaction vessel 60 was raised to 380 ° C. and held for 1 minute (reaction time: 1 minute). Thereafter, the temperature was cooled to 150 ° C., and the internal pressure was returned to normal pressure. When the temperature is cooled to 150 ° C., the liquid supply path is switched, xylene is sent from the solvent tank 62 to the pressure resistant reaction vessel 60 by the pump 64, the inside of the pressure resistant reaction vessel 60 is replaced with xylene, and the internal pressure is increased again to 1 MPa. did. After stabilizing the pressure, xylene was continuously fed at a flow rate of 10 ml / min for 60 minutes. Thereafter, the feeding of xylene was stopped, and the temperature and pressure in the pressure-resistant reaction vessel 60 were returned to normal temperature and pressure, and then a white lump was recovered from the solid-liquid separator 67.
An infrared spectroscopic analysis of this recovered product confirmed that it was only polyethylene.
[0060]
【The invention's effect】
  As explained above, according to the present invention,Crosslinked polyolefin and carbon-containing polyolefinFrom waste consisting ofCarbon-containing polyolefinHighly reusable without separationUncrosslinked polyolefinCan be recovered.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing the configuration of a processing apparatus used in a first embodiment of the present invention.
FIG. 2 is an enlarged view of the pressure resistant reaction container of FIG.
FIG. 3 is a diagram schematically showing a configuration of a processing apparatus used in a second embodiment of the present invention.
4 is a diagram schematically showing an example of a container for storing waste used in the processing apparatus of FIG. 3. FIG.
FIG. 5 is a diagram schematically showing a configuration of a processing apparatus used in a third embodiment of the present invention.
[Explanation of symbols]
1, 60 ... Pressure-resistant reaction vessel 2, 32, 37, 61 ......... Pure water tank
3, 33, 38, 63, 64 ... pump 12 ... mesh tray
13 …… Mesh-like container 21 …… Preload chamber 22 …… Reaction chamber
23 …… Decompression chamber 25 …… Receiver 50 …… Container 51 …… Inner container
52 …… Outer container 62 …… Solvent tank 67 ……… Solid-liquid separator

Claims (1)

A waste made of a crosslinked polyolefin and a carbon-containing polyolefin is accommodated in the inner container of a double-structured container consisting of a coarse mesh-shaped inner container and a fine mesh-shaped outer container, and introduced into the preloading chamber. said preload chamber is pressurized by the water, the vessel containing the waste, the temperature 200 ° C. ~ 700 ° C., then transferred to the reaction chamber supercritical water or subcritical water area of the pressure 0.1 MPa ~ 100 MPa are formed required Holding the time to decompose the crosslinked polyolefin to produce an uncrosslinked polyolefin , transferring the container containing the uncrosslinked polyolefin to a decompression chamber pre-pressurized with water, depressurizing the decompression chamber, A waste treatment method, wherein the container is discharged from the decompression chamber and the uncrosslinked polyolefin transferred to the outer container is recovered.

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