JP2005307105A - Apparatus for removing flame retardant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus that can solve such a problem, in a process of removing a flame retardant contained in a flame retarding resin by using a solvent for extracting the flame retardant, that it is difficult to remove the flame retardant effectively using only one kneading machines because of its short length. <P>SOLUTION: The apparatus comprises connected plural kneading machines by dividing the process, the first kneading machine is for heating and melting the flame retardant containing-resin, the next one is for mixing and kneading the resin with a solvent and finally for exhausting the solvent, and the last one is for removing remaining solvent by evacuation and for discharging a non-flame retarding resin that is cooled and then pelletized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flame retardant removing apparatus that removes a flame retardant from a resin containing a flame retardant used in an exterior resin casing of a general consumer device such as a home appliance.

  Conventionally, in general consumer equipment such as a television, a lot of synthetic resin is used for an exterior housing or the like. Typical examples include thermoplastic resins such as polystyrene, polypropylene, ABS, and high impact polystyrene (HIPS) with improved impact resistance. Since these materials have low flame retardancy, they are generally made flame retardant by adding and containing various flame retardants and flame retardant aids for use as exterior casings.

  As flame retardants, halogen-based flame retardants that can be made flame retardant with a relatively small amount of addition and are inexpensive are often used. In particular, brominated flame retardants are used in polystyrene. There is no device for removing additives such as flame retardants from these resins. Therefore, using a solvent that dissolves the resin without dissolving the flame retardant, the resin containing the flame retardant is mixed with the solvent, and the flame retardant precipitates without dissolving, so the resin and the flame retardant can be separated. . However, since the resin is dissolved in the solvent, the molecular weight is reduced and the resin returns to the monomer. Even if the solvent and the resin are separated, the material cannot be recycled because it does not return to its original state.

  However, the Home Appliance Recycling Law imposes an obligation on producers to collect and reuse waste home appliances, and appropriate processing is required. The flame-retardant resin casing used for the exterior is currently only incinerated or disposed of by landfill. However, the aforementioned halogen-based flame retardants, particularly bromine-based flame retardants, tend to burn incompletely due to their high flame retardancy. Moreover, if incinerated under inadequate conditions such as incineration at low temperatures, there is a concern of dioxin generation. Producers are exploring the use of phosphorus-based flame retardants as an alternative, but in phosphorus-based inferior flame retardants, the content is greatly increased in order to obtain the same flame resistance as halogen-based flame retardants. Must be increased to The cost is high, and it is not a preferable method from the viewpoint of environmental impact at the time of disposal. Therefore, the switch to phosphorus system is not progressing.

  Furthermore, there is an urgent need to prevent the depletion of petroleum resources from the viewpoint of global energy. Recycling resin is being worked on. Examples of the flame retardant-containing resin include acid treatment (for example, Patent Document 1) and high-temperature treatment (for example, Patent Document 2). These are the contents that the resin and the flame retardant are separated and thermally recycled.

Therefore, there is no conventional example regarding a material recycling method in which the flame retardant is separated without deteriorating the properties of the resin and the resin is reused. A method for modifying and separating a resin from a flame retardant-containing resin is described in Patent Document 3, for example.
JP-A-6-157812 JP-A-8-299759 Japanese Patent Laid-Open No. 10-195234

  In order to remove the flame retardant and recycle the resin material, it is possible to use the resin after removing the flame retardant without modifying the resin so that the resin can be used for general-purpose applications similar to the original resin. Therefore, technology for removing the flame retardant is necessary. This apparatus provides an apparatus for removing a flame retardant from a flame retardant-containing resin efficiently and at a low cost while minimizing changes in resin properties.

  In order to remove the flame retardant from the flame retardant-containing resin and material recycle the resin, the pulverized flame retardant-containing resin is put into a small kneader combined with multiple devices, heated and melted, and further specified. The present invention proposes an apparatus for recovering the reduced pressure by injecting and discharging the solvent from the middle, dissolving and extracting the flame retardant in the solvent, and further evacuating the solvent remaining in the resin.

  As described above, by using the apparatus of the present invention, the non-flame retardant resin can be reused by incineration and landfill processing without wasting the flame retardant-containing resin from a large amount of waste home appliances with relatively inexpensive equipment. It has the effect of being able to recycle materials, and solves environmental problems.

  The present invention is a resin processing apparatus characterized in that a solvent and a resin are kneaded in a kneader constituted by a plurality of apparatuses when the flame retardant is extracted and removed from the resin containing the flame retardant. Are combined and a kneader is used to remove the flame retardant and the solvent used to extract the flame retardant, thereby producing a non-flame retardant resin.

  In the present invention, the first kneading machine is characterized in that when the solvent and the resin are sufficiently kneaded and the resin is discharged, only a very small amount of solvent permeating into the resin is contained. Therefore, this kneader has the effect of removing the flame retardant from the resin.

  In the final stage kneader, the solvent is completely removed by exhausting the resin from the slightly remaining solvent discharged from the previous stage kneader by using a vacuum pump. It has the effect of producing a non-flame retardant resin characterized in that the flame retardant and the solvent are removed.

  Further, the present invention is characterized in that L / D of the plurality of kneaders is at least 7.5 or more and at most 30 or less, and the action of removing the flame retardant and the solvent used in a short process have.

  The present invention is an equipment for producing a non-flame retardant resin, characterized in that when connecting kneaders, the extrusion pressure of the front kneader is increased and the raw material is supplied to the rear kneader.

  In the present invention, a biaxial screw is arranged vertically when exhausted by a vacuum pump from a resin having a slight solvent remaining discharged from a previous kneader, and a screw and a mold are arranged in an upper portion. This is a facility for producing a non-flame retardant resin characterized in that a space is provided between the two to increase the exposed area.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The flame retardant removing apparatus of the present embodiment extracts at least one flame retardant from a resin by bringing the resin containing the flame retardant into small pieces by a crusher and bringing the resin and solvent into contact with each other in a plurality of kneaders. The residual solvent is removed by separating and further evacuating in a subsequent kneader.

  The flame retardant-containing resin refers to a resin or scrap material that has become unnecessary in the resin production process, or a resin that has been used for waste home appliances collected from the market, regardless of thermoplasticity or thermosetting property. Including at least one flame retardant to add flame retardancy, other flame retardant aids, lubricants, stabilizers, antioxidants, colorants, flow modifiers, release agents, etc. required for resin molding It is a resin containing an additive. Moreover, even if the surface is painted, it does not matter as long as the cross section is exposed by crushing.

Flame retardants include bisphenol A type flame retardants such as tetrabromobisphenol A (TBA), flame retardants such as decabromodiphenyl ether, octabromodiphenyl ether, tetrabromodiphenyl ether, tribromophenol, ethylenebistetrabromophthalimide, hexa Brominated flame retardants such as bromocyclododecane, TBA polycarbonate oligomers, bistribromophenoxyethane, brominated polystyrene, TBA epoxy oligomers, chlorinated flame retardants such as perchlorocyclopentadecane, chlorendic acid, chlorinated paraffin, phosphorus-based flame retardants And nitrogen compound flame retardant inorganic flame retardant.

  The flame retardant in the resin may be used alone or in combination with a plurality of the various flame retardants described above. The content varies depending on the required flame retardant grade, but is generally from several wt% to 50 · 60 wt%.

  The type of resin is not particularly selected, but is particularly effective for styrene resins. Examples of styrene-based materials include polystyrene, high impact polystyrene, styrene-budadiene-acrylonitrile, styrene-butadiene, poly-α-methylstyrene, styrene-acrylonitrile, and styrene-maleic anhydride.

  The above resins may be used alone, but may be used by blending with other resins. The molecular weight is not particularly limited, but is preferably about 3,000 to 1,000,000.

  In addition, the kneader in this embodiment is a single unit or a biaxial unit and has a plurality of unit configurations connected to each other, and refers to a kneader or the like used for resin molding or resin kneading. -There is a place where the solvent can be injected and discharged at the middle part, and the structure can be evacuated near the resin discharge part, including those improved as appropriate.

  The solvent used in the present embodiment can separate the flame retardant dissolved in the distillation operation, and the solvent can be recycled.

  Hereinafter, the flame retardant removing apparatus of the present embodiment will be described in detail with reference to FIG.

  The flame retardant-containing resin that has been used in the collected waste home appliance housing or the like is pulverized into pellets having a size of 1 to 10 mm, and then charged into the hopper 4. When this is put into the first-stage kneader 1, it is heated and melted in the kneader 1, further kneaded by the screw 15, and sequentially pushed out toward the outlet on the right side. This extruder may be of a normal L / D length for resin molding, but if the screw configuration is devised, a kneader dedicated to kneading with an L / D of about 10 or less, which is less than a fraction of the price. Can also be used. As a result, the price of the apparatus is greatly reduced, and it is possible to produce at a low cost.

  From the tube 6 provided in front of the resin discharge portion of the first-stage kneader 1, the solvent is injected at a high pressure and discharged from the tube 5. During this time, the solvent and the resin come into contact with each other at a high temperature, and the flame retardant is eluted in the solvent. The flow of the solvent and the resin is opposite, and the resin always comes into contact with a new solvent near the discharge port, so that it is finally washed with a solvent in which the flame retardant is hardly dissolved. Although the heating temperature of this kneader varies depending on the resin, it is in the range of about 100 to 200 ° C., and about 180 ° C. in the case of high impact polystyrene.

  As a result of studying various solvents, a glycol ether type solvent was selected as one in which the flame retardant dissolves relatively easily, the resin component hardly dissolves, and has little influence on the environment. Specifically, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol propyl ether, Examples include triethylene glycol butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol propyl ether, and tripropylene glycol butyl ether. Moreover, if it is a range which does not drop the dissolving power of a flame retardant in these solvents, a well-known additive can be added as needed. For example, antibacterial agents, antifungal agents, antioxidants, pest repellents, surfactants, coloring agents, foaming agents, flow promoters and the like.

  Thereafter, the discharged resin enters the kneader 2 through the pipe 7 which is a joint portion with the kneader 2 in the subsequent process. In this kneader, the solvent remaining in the resin is removed by suction from the vacuum exhaust port 13 and is discharged linearly through the mold 9. Since the purpose of this kneading machine is to remove the solvent, it is not necessary to have the same L / D as that of the kneading machine 1, and if it can be reduced to the desired solvent content, a smaller and lower price kneading machine can be obtained. It is also possible to use it.

  The resin 10 thus extruded is then cooled in a water tank, cut to a predetermined length by a pelletizer 12, and can be regenerated as non-flame retardant resin pellets 16 again.

(Embodiment 2)
In this embodiment, a material obtained by pulverizing a resin used in an exterior casing of a waste TV is used as a raw material. The type of resin is high impact polystyrene, and the flame retardant contained is TBA (tetrabromobisphenol A). The average molecular weight was about 40,000. According to GPC analysis, the flame retardant content was about 17%.

  This was put into the hopper 3 and put into the first stage kneader 1. The temperature setting of the kneader is 180 ° C. Dipropylene glycolol was used as the solvent. The solvent was poured into the kneader with the pressure increased using a gear pump in a direction opposite to the resin flow direction. When the discharged solvent was analyzed, it contained about 7% TBA.

  Next, the resin moves through the connection pipe 7 to the second kneader 2. The mixture is heated again in the kneader and evacuated from the vent port 14 to extract the solvent remaining in the resin. Note that the solvent contained in the exhaust gas returns to liquid again by cooling in the exhaust process, and can be reused many times.

  The resin is discharged in a plurality of lines from a mold attached to the outlet of the second-stage kneader 2, cooled by being immersed in the cooling water tank 11, and cut into a pellet size by the pelletizer 12. When this resin was analyzed, the residual solvent ratio was 0.1% or less, and the residual flame retardant ratio was 0.05% or less. When various physical properties of this resin were measured, the physical properties such as Charpy impact strength, DuPont impact value, Vicat softening point and the like were all about 1.2 times that of the initial high impact polystyrene. This is because the physical properties that have been lost by adding the flame retardant to the resin have returned to the original level of the resin by removing the cause of the flame retardant. The molecular weight of the resin was 38500, and there was almost no change from the initial value.

  That is, the flame retardant could be removed from the resin with almost no deterioration of the resin properties.

(Embodiment 3)
When removing a flame retardant from a resin containing a flame retardant using a solvent, the embodiment of the present invention can be most simplified when only one type of solvent is used.

  FIG. 2 is a diagram showing a process for removing the flame retardant by using only one kind of solvent from the resin containing the flame retardant. In the process shown in FIG. 2, the process from putting the pulverized resin into the supply port to extruding the molten resin at a high pressure is carried out with a single kneader. Mixing the melted resin and solvent, extracting the flame retardant contained in the resin into the solvent, separating it, and then extruding the resin from which the flame retardant has been removed at a high pressure. Implement on the machine. The resin melted in the first kneading machine was connected to the kneading machine in the subsequent process with a pipe or the like provided with a heater or the like to supply.

  After the flame retardant contained in the resin is removed, the molten resin containing the solvent is decompressed, the solvent remaining in the resin is exhausted and removed, and the process of extruding the resin at a high pressure is further performed. Carry out with another kneader. Finally, the resin is extruded from a kneader and cooled, and then cut with a cutter to form a pellet. The resin melted in the second kneader was connected to the kneader in the subsequent process with a pipe or the like provided with a heater or the like to supply.

  The flowchart shown in FIG. 2 is an example of removing the flame retardant with one kind of solvent, but there are a plurality of additives contained in the resin, and each of them is removed using different solvents. If necessary, the configuration shown in FIG. 2 can be repeated many times.

  FIG. 3 is a schematic view showing an apparatus configuration in which the flame retardant is removed using only one type of solvent from the resin containing the flame retardant. The resin 23 is supplied to the resin heating kneader 17. The resin 23 is melted by the resin heating kneader 17. The molten resin 23 is extruded from the resin heating kneader 17 and supplied to the flame retardant removing kneader 25. In the flame retardant removing kneader 25, the solvent 22 is injected into the solvent supply port 6. The solvent 22 injected into the flame retardant removing kneader 25 is discharged from the solvent outlet 5.

  On the other hand, the resin 23 is supplied from the side near the driving motor 8 in FIG. By reversing the direction of movement of the solvent 22 and the resin 23, it is possible to contact the solvent 22 and the resin 23 in a state where the concentration of the flame retardant is always low. The concentration of the flame retardant contained in the resin 23 in the mold of the flame retardant removing kneader 25 becomes lower as it goes to the left. The resin 23 from which the flame retardant has been removed is supplied to the degassing kneader 18 at a high pressure. The degassing kneader 18 is evacuated to a reduced pressure state. The solvent 22 remaining in the resin 23 can be removed by evaporating in a reduced pressure state.

  The resin 23 from which the solvent 22 has been removed is extruded from the degassing kneader 18 at a high pressure, cooled, and then cut by a cutter into a pellet shape. The pelletizer 12 is an apparatus that cools the resin 23 extruded from the kneader and cuts it with a cutter to form a pellet. By adopting such an apparatus configuration, it is possible to optimize the scale of the apparatus corresponding to each process.

  In FIG. 3, the resin heating kneader 17 that only melts the resin 23 and the degassing kneader 18 that removes the solvent 22 remaining in the resin 23 after removing the flame retardant can be reduced in size. Is possible. The objective can be achieved if only the flame retardant removing kneader 25 for mixing the resin 23 and the solvent 22 to remove the flame retardant is enlarged.

  FIG. 6 shows an example in which the process shown in FIG. 2 is carried out with one kneader using a conventional kneader. Resin 23 is supplied to hopper 3 and melted by resin heating unit 26. The molten resin 23 is then sent to the flame retardant removal unit 27. The flame retardant removing portion 27 is formed with a screw having a reverse feeding configuration at both ends to increase the pressure with the raw material made of the resin 23. In the section sandwiched with the raw material at a high pressure, the solvent 22 was injected from the solvent supply port 6 and the solvent 22 was discharged from the solvent discharge port 5. With this configuration, since the solvent 22 can be supplied in the direction opposite to the extrusion direction of the resin 23, the solvent 22 and the resin 23 in a state where the concentration of the flame retardant is always low can be brought into contact.

  Then, the resin 23 from which the flame retardant has been removed is sent to the deaeration unit 28. In the deaeration unit 28, the solvent 22 remaining in the resin 23 can be removed by evaporating it from the vent port 14 in a reduced pressure state. The resin 23 from which the solvent 22 has been removed is extruded from a kneader, cooled, and then cut with a cutter to form a pellet.

  In the conventional kneader, since all the processes are performed by one unit, the apparatus becomes long and the equipment cost becomes extremely high. In addition, it is necessary to increase the pressure with the raw material at two locations on both ends of the flame retardant removing portion 27, and it is necessary to maintain the balance between the solvent injection pressure and the pressure due to the raw material at two locations. Since the pressure balance is adjusted simultaneously at two locations, there is a problem that it takes time until the manufacturing conditions are stabilized. However, as shown in the present invention, by dividing and connecting the respective processes, it is possible to stabilize in a short time due to the presence of pressure to send out the resin even if the screw configuration on the material supply side is not reversed. And can be manufactured. FIG. 4 shows the principle.

  FIG. 4 shows the configuration of the screw in the kneader 25 for removing the flame retardant. In order to remove the flame retardant from the resin 23, the resin 23 is supplied to the hopper 3, the solvent 22 is injected from the solvent supply port 6, and the solvent 22 is discharged from the solvent discharge port 5. The resin 23 supplied from the hopper 3 is extruded by the feed direction screw 20, but the pressure is increased by the reverse direction screw 21 on the way. As shown in FIG. 4, the solvent 22 is supplied at a position before the pressure is increased by the reverse screw 21. The solvent 22 supplied at this position does not flow in the extrusion direction but flows in the opposite direction because the pressure of the resin 23 is high. The solvent 22 that has flowed in the opposite direction is discharged from the solvent discharge port 5 in an open state because the pressure is high in the vicinity where the resin 23 is supplied.

  Based on such a principle, in the conventional example, the reverse direction screw 21 is provided at two locations on the solvent supply side and the discharge side, and the solvent flows in the direction opposite to the resin extrusion direction. According to the above, the solvent discharge side is a normal feed direction screw 20, and the solvent 22 can flow in the direction opposite to the extrusion direction of the resin 23. Thereby, the length of the section which mixes and extracts resin 23 and solvent 22 in order to remove a flame retardant can be extended, and it becomes possible to use a kneader effectively.

  FIG. 5 is a view showing a cross section of a mold provided with a vacuum pump. A vent port 14 is provided above the mold 9. It is possible to evacuate from the vent port 14. As shown in FIG. 5, two screws 15 are arranged vertically, and an upper space 24 that is a gap is provided between the upper screw 15 and the mold 9.

  When the resin 23 from which the flame retardant has been removed passes through the mold 9, the upper space 24 exposes the surface of the resin 23. The solvent 22 remaining in the resin 23 evaporates from the sealed space that is in a reduced pressure state due to the exposure of the surface. By securing a certain amount of space in the upper space 24, the solvent 22 remaining in the resin 23 is easily evaporated. Thereby, the solvent 22 remaining in the resin 23 can be efficiently removed even in a short section.

  The apparatus according to the present invention can change a resin containing a flame retardant from a waste home appliance to a non-flame retardant resin, and thus has an effect of reducing waste by material recycling. The apparatus according to the present invention can also be useful for recycling furniture, automobiles, buildings, etc. that generally use resin. It will be an effective means of solving environmental problems such as a shortage of disposal sites due to increased waste.

Schematic of the flame retardant removing apparatus which is an embodiment of the present invention Diagram showing the process of the equipment Schematic of a flame retardant removing apparatus which is another embodiment of the present invention The schematic diagram which showed the structure of the screw of the kneading machine of the flame retardant removal apparatus which is one Example of this invention. Sectional drawing of the metal mold | die equipped with the vacuum pump in the flame retardant removal apparatus which is one Example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st stage kneader 2 2nd stage kneader 3 Hopper 4 Crushed resin 5 Solvent discharge port 6 Solvent supply port 7 Connection part 8 Motor 9 Mold 10 Discharge resin 11 Cooling water tank 12 Pelletizer 13 Exhaust 14 Vent port 15 Screw 16 Pellet 17 Kneader for resin heating 18 Kneader for degassing 19 Resin delivery port 20 Feed direction screw 21 Reverse direction screw 22 Solvent 23 Resin 24 Upper space portion 25 Flame retardant removal kneader 26 Resin heating portion 27 Flame retardant removal Part 28 Degassing part

Claims (3)

A flame retardant removing apparatus for extracting and removing a flame retardant from a resin containing a flame retardant, comprising a plurality of kneaders connected, and kneading a solvent and a resin in the kneader Removal device. The processing apparatus according to claim 1, wherein the final-stage kneader is equipped with a vacuum pump. A flame retardant removing apparatus constituted by connecting a plurality of kneaders, wherein the first kneader in the first step melts only the resin, and the second kneader in the next step is the first kneader. The melted resin discharged from the solvent and the solvent are kneaded, the solvent is discharged, and the third kneader is evacuated from the resin discharged from the second kneader using a vacuum pump. A flame retardant removing device characterized by removing the flame.

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