JPH093239A - Styrene-based synthetic resin waste treatment and recycling method - Google Patents

Abstract

PURPOSE: To produce a regenerated polystyrene having high quality at a low cost under the recovery of a solvent by dissolving styrene synthetic resin waste in the solvent, removing foreign materials by centrifugation and treating the separated liquid by fractional distillation. CONSTITUTION: Styrene synthetic resin waste (especially, foamed styrenes waste, etc.) is dissolved in a volume reducing tank containing a solvent (e.g. d-limonene, methyl ethyl ketone, benzene, toluene or methyl acetate), the concentration of the dissolved liquid is adjusted in an adjusting tank, and subsequently the foreign materials (e.g. labels and fish scales) in the liquid is removed by centrifugation. The separated liquid is subjected to fractional distillation under a reduced pressure of 40-60Torr at 210-260 deg.C, and the solvent is recovered and at the same time the styrene is recovered as regenerated pellets. Further, the centrifugation is preferably carried out at normal temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating styrene-based synthetic resin waste, particularly styrofoam waste, which is used for treating styrene-based synthetic resin waste and recycling it as recycled polystyrene pellets. The present invention relates to a method for treating and recycling synthetic resin waste.

[0002]

2. Description of the Related Art Styrenic synthetic resins are used in various industrial products.
Widely used in parts, containers, packaging materials, etc. Therefore, they become wastes at every stage of distribution, and they tend to increase as industrial wastes and general wastes. Of the styrene-based synthetic resins, Styrofoam is lightweight and has excellent impact resistance, heat insulation, and water resistance.
It is widely used for packing materials such as A-equipment, food trays, and building materials for heat insulation. However, the volume of styrofoam is expanded by 10 to 70 times, and when it becomes a waste, the collection freight rate becomes expensive and it is regarded as a difficult waste to handle.

Most of these styrene-based synthetic resin wastes are incinerated or landfilled as they are, and it is an important task to make efforts for recycling in order to protect the global environment. Regarding the recycling of Styrofoam waste, it is pulverized and used as a building material such as mortar admixture, lightweight concrete or as a soil conditioner, it is heat-melted and recovered as an ingot or pellet, and it is dissolved in a solvent and then pelletized. Alternatively, a method of collecting as an adhesive, a method of recovering heat by incineration, or the like has been implemented or proposed.

[0004]

The problems in the conventional method of treating and disposing of styrene-based synthetic resin waste, particularly styrofoam waste, and recycling can be summarized as follows. (A) Treatment Disposal Incineration Disposal is difficult in an incinerator for general waste, such as high calorific value and easy generation of unburned carbon due to incomplete combustion. Landfill disposal In the case of Styrofoam waste, the apparent specific gravity is low, so the collection and transportation costs are high, and the landfill disposal site occupies a large volume.

(B) Recycling The problems in the method for recycling styrofoam waste are
It is as follows. The target is limited to those that do not contain pulverized foreign matter and are not contaminated, and the demand is limited. Thermal volume reduction The melting volume method by heat is mainly applied to the method of melting and defoaming in the extruder and pelletizing, and the method of making ingot by various volume reducing machines such as electric heating type, hot air heating type, far infrared heating type. Be separated. With these methods, it is difficult to remove foreign substances that are mixed in, and it is difficult to develop applications for recycled products. 3
In some cases, it may be heated up to near 00 ° C. In this case, the molecular weight and the oxidation are caused by the thermal decomposition, and the physical properties of the recycled product are unavoidably deteriorated. Even during operation, a odor is generated due to the generation of styrene monomer during thermal decomposition, which worsens the working environment. Solvent Dissolution Method For example, in Japanese Unexamined Patent Publication (Kokai) No. 6-32938, styrene-based synthetic resin waste is dissolved in a solvent, and the solution is filtered to remove foreign matters and then distilled to recover polystyrene. Is heated before being filtered. It is considered that this is because it is difficult to perform filtration efficiently because the viscosity of the solution is high, so that a method of heating and then filtering is taken. Further, in such a filtration method, since the filter material is clogged with foreign matter, it is necessary to wash or replace the filter material, which is a large load in practical use. Incineration heat recovery As mentioned in incineration, incineration is difficult, and the economic memet due to heat recovery is small.

The present invention is concerned with the difficulty of incineration / landfill disposal, high collection cost, and foreign matter / dirt, which are problems in the treatment and disposal of these conventional styrene-based synthetic resin wastes, particularly styrofoam wastes. Styrene-based synthetic resin waste treatment and resource recycling method that eliminates the contamination of odor, the generation of bad odor, the deterioration of recycled product quality, etc., and can economically obtain high-quality recycled polystyrene under a good working environment. The purpose is to provide.

[0007]

According to the method of the present invention, styrene-based synthetic resin waste is dissolved in a solvent in a volume reducing machine containing the solvent, and the solution is transferred to an adjusting tank to adjust the concentration.
Foreign substances in the dissolved solution are removed by centrifugation, and the separated solution is distilled and separated at a temperature of 210 to 260 ° C. under a reduced pressure of 40 to 60 Torr to recover the solvent and the dissolved polystyrene as regenerated pellets. It is characterized by doing. Further, the above method is characterized in that a solution obtained by dissolving styrene-based synthetic resin waste in a solvent is subjected to centrifugal separation treatment at room temperature.

The present invention will be described below in detail with reference to the drawings. FIG. 1 is a system diagram showing the function of a volume reducer of the present invention that dissolves styrene-based synthetic resin waste with a solvent to reduce the volume, and FIG. 2 shows a solution obtained by the volume reducer. It is a flow sheet of equipment for treating and recovering the solvent and the regenerated polystyrene. The volume reducer shown in Fig. 1 is a styrene-based synthetic resin waste inlet, a dissolution tank for storing a solvent and dissolving the input styrene-based synthetic resin waste, and a dissolved solution in a shipping container. It is composed of a discharge port for discharging. In addition, it is desirable to install a crushing mechanism in the volume reducing machine in order to efficiently dissolve and reduce the volume of the styrene-based synthetic resin waste that has been input.

This volume reducing machine is usually installed in a place where styrene synthetic resin waste is generated, such as a wholesale market, a home electric appliance distribution center, a supermarket, and a factory. In the dissolution / volume reduction process, after filling the dissolution tank with a solvent, styrene-based synthetic resin waste is charged from the charging port so that the solvent is dissolved / volume-reduced in the solvent. As the solvent, terpenes such as d-limonene and dipentene, methyl ethyl ketone,
Ketones such as diethyl ketone, methyl-n-propyl ketone, hexanone, benzene, toluene, xylene,
Aromatic hydrocarbons such as ethylbenzene, ethylene chloride,
Halogenated hydrocarbons such as trichlorethylene and carbon tetrachloride, esters such as methyl acetate, ethyl acetate and isoamyl acetate can be used. The dissolution treatment with these solvents can be performed at room temperature, but a heater for heating the solvent in the dissolution tank can be provided on the outer surface of the dissolution tank in order to accelerate the dissolution rate. Further, in the case of dissolving the styrene-based synthetic resin waste in the solvent in this way, if the amount of dissolution is too large, the dissolution rate will be extremely slow, and the viscosity of the solution will be extremely high, and handling such as discharge and liquid feeding will be very difficult. It will be difficult. On the other hand, if the amount of dissolution is too small, the treatment efficiency decreases, so the dissolution concentration of the styrene-based synthetic resin waste is preferably 20 to 30% by weight. The lysate thus obtained is discharged into a shipping container,
After being transported to the processing facility, it is processed intensively.

The processing equipment shown in FIG. 2 includes a control tank for receiving and mixing a solution to adjust the concentration: a feed pump for feeding the solution under pressure: 2, a centrifugal separator for removing foreign matters from the solution. Machine: 3, Overflow tank for temporarily holding the clarified solution from the centrifuge: 4, Feed pump for feeding the clarified solution under pressure, 5, Distiller for separating solvent and polystyrene from the solution: 6, Melting Extrusion pump for extruding polystyrene as a strand: 7, Cooling tank for cooling the strand: 8, Pelletizer for pelletizing this strand: 9, Condenser for condensing evaporated solvent: 10, Vacuum for operating the distiller in vacuum Pump: 11, recovery solvent tank for storing the recovered solvent: 12, and recovery solvent pump for discharging the recovery solvent: 13 It is. In processing the styrene-based synthetic resin waste solution, the solution contained in a plurality of shipping containers is first put into the adjusting tank 1. The solution is stirred in the adjusting tank 1 to adjust the concentration. Then, this solution is placed in a centrifugal separator 3 at room temperature.
Foreign matter (solid matter) in the centrifuge 3
Are removed. In the centrifugation process, it is possible to heat the dissolution liquid to lower the viscosity in order to increase the separation efficiency, but solid substances can be sufficiently removed even in the centrifugation process at room temperature, and at the room temperature condition for safety reasons. Processing is desirable.

The dissolved solution from which the foreign matters have been removed is then distiller 6 whose pressure is reduced to 40-60 Torr by vacuum pump 11.
And is separated into a solvent and polystyrene by the distiller 6. The distiller efficiently separates the solvent, and in order to discharge the separated polystyrene in a molten state, it is heated to 210 to 260 ° C. by the high temperature heating medium. The separated solvent is liquefied by the condenser 10, stored in the recovery solvent tank 12, and then discharged by the recovery solvent pump. This collected solvent is transported to the installation site of the volume reducer,
Reused as a solvent for dissolving and reducing the volume of styrene-based synthetic resin waste. On the other hand, the molten polystyrene discharged from the distiller 6 is extruded as a strand by an extrusion pump 7 equipped with a die. The strands are water-cooled in the cooling tank 8 and then pelletized by the pelletizer 9. As a result, the styrene-based synthetic resin waste is recovered as high-quality regenerated polystyrene pellets.

[0012]

According to the method for treating and recycling waste of styrene type synthetic resin of the present invention, the following effects can be obtained. (A) By installing a volume reduction machine at the place where styrene-based synthetic resin waste is generated, it can be dissolved even in small-scale places.
Volume can be reduced. In addition, the cost of transportation can be significantly reduced by discharging the dissolved solution into a shipping container and shipping it. (B) Collecting the dissolved solution, adjusting the concentration, and then collectively processing the solution. That is, the recovery of the solvent and the regenerated polystyrene from the solution can be carried out inexpensively in a large-scale processing facility. (C) By using a centrifuge, it is possible to efficiently remove foreign substances mixed in the styrene-based synthetic resin waste, and to collect high-quality regenerated polystyrene. In particular, it is not necessary to remove foreign substances such as labels attached to the Styrofoam, attached fish scales and fine dust in advance, and the treatment can be performed without human intervention. Further, these foreign substances can be mechanically removed without heating the solution in advance, and high quality regenerated polystyrene can be obtained very efficiently.

(D) Styrofoam waste may have water and salts attached to it, which cannot be removed by a filter, but can be easily removed by using a centrifuge. (E) In the distillation separation treatment, polystyrene is 210-2
Although it is heated to 60 ° C and discharged in a molten state, the distiller is operated under a reduced pressure of 40 to 60 Torr, so that oxidation does not easily occur even at high temperature, and the residence time is short, so the molecular weight due to thermal decomposition is low. The drop is small. Therefore, deterioration of the physical properties of polystyrene is small, and high quality regenerated polystyrene can be obtained. (F) Most of the solvent used for dissolution is recovered by distillation separation and reused for dissolution again. Therefore, the processing cost can be reduced. (G) By using a natural solvent d-limonene or dipentene as a solvent for dissolution, it is possible to treat styrene-based synthetic resin waste under a favorable working environment without adversely affecting the environment and the human body.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. Example 1 A used styrofoam fish box having a large foreign substance such as a label or fish scale attached thereto was dissolved in d-limonene to give 30
After making it into a weight% solution, use a bowl-type continuous centrifuge for test at room temperature under a centrifugal force of 1,200G.
Processing was performed at a supply rate of 0 liter / h, and a foreign matter removal test was performed. As a result, foreign substances such as labels and fish scales were easily separated and removed, and turbidity that seemed to be due to extremely fine dust was observed in the obtained treatment liquid, but no visible foreign substances were observed. It was

Example 2 A test bowl type continuous centrifuge was used to examine the removal rate of fine foreign matters such as dust adhering to the used Styrofoam fish box. A used styrofoam fish box was dissolved in d-limonene to obtain a solution of 25% by weight and 30% by weight, and then filtered through a 5-mesh wire net to remove large foreign matters. The amount of foreign matter contained in each solution was 0.88% and 0.72, respectively, by weight ratio to polystyrene.
%Met. These solutions were fed to a centrifuge at room temperature and the amount of foreign matter in the obtained treatment liquid was measured. The experimental conditions and results are shown in Table 1.

[0016]

[Table 1]

Further, this experimental result was compared with a foreign matter removal test by filtration. The 30 wt% solution prepared by the above-mentioned centrifugation test (filtered with a 5 mesh wire mesh) was filtered using a filter cloth made of Tetoron to examine the removal rate of foreign substances. Table 2 shows the relationship between the mesh size of the filter cloth and the foreign matter removal rate.

[0018]

[Table 2]

As a result, it was found that the removal rate of foreign matters by the bowl type continuous centrifuge was about the same as that by the filtration with the 37 μ filter cloth. In this filtration test, the viscosity of the solution was high at room temperature and the filtration could not be carried out smoothly, so it was necessary to heat the solution to about 70 ° C. In addition, a solution of a used styrofoam fish box dissolved in d-limonene heated to 70 ° C to 20% by weight (the amount of foreign matter is
It was 0.8% with respect to polystyrene. ) Was used to conduct a filtration test with a wire mesh having an opening of 53 μm. As a result, the amount that can be treated before the filter material is clogged is about 100 liters per 1 m ² of the filter material, which proves to be a problem in practical use. As described above, it was found that the centrifugal separation treatment is extremely useful as compared with the conventionally considered filtration treatment.

Example 3 30 obtained by centrifugation in Examples 1 and 2
40% by weight of the solution was collected and sent to a distiller.
Perform distillation separation at 60 torr, 210-260 ° C.,
Recovery of d-linemon and polystyrene was performed. The recovered recycled polystyrene pellets are compression molded to a thickness of 2
mm plate was prepared and visually observed,
No visible inclusion of foreign matter was observed. In addition, the physical properties of the recovered regenerated polystyrene pellets were measured. The results were as shown in Table 3.

[0021]

[Table 3]

As described above, the regenerated polystyrene had a very high quality and was reusable as a polystyrene raw material. On the other hand, the recovered d-linemon had no change in physical properties and could be reused as a solvent.

[0023]

As described in detail above, according to the method for treating and recycling styrene synthetic resin waste of the present invention, it is possible to dissolve styrene synthetic resin waste safely, easily and efficiently.
Volume can be reduced, and it can be collected and transported at a low transportation cost.
High-quality regenerated polystyrene can be obtained with a higher recovery rate than the collected solution. Furthermore, since the solvent used for dissolution / volume reduction can be recovered and reused at a high recovery rate, economical processing is possible.

[Brief description of drawings]

FIG. 1 is a system diagram showing the function of a volume reducing machine of the present invention, which dissolves styrene-based synthetic resin waste with a solvent to reduce the volume.

FIG. 2 is a flow sheet of equipment for treating a solution obtained by a volume reducing machine to recover a solvent and regenerated polystyrene.

[Explanation of symbols]

 1 Adjustment Tank 2 Feed Pump 3 Centrifuge 4 Overflow Tank 5 Feed Pump 6 Distiller 7 Extrusion Pump 8 Cooling Tank 9 Pelletizer 10 Condenser 11 Vacuum Pump 12 Recovery Solvent Tank 13 Recovery Solvent Pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadanori Miura 2-3-11 Higashishinagawa, Shinagawa-ku, Tokyo Ube Industries, Ltd. Tokyo head office (72) Inventor Kenji Fujioka Oki, Ube, Yamaguchi Prefecture Mountains off Ube, Japan 525-14 Ube Computer Corporation Ube Factory

Claims (2)

[Claims] 1. A styrene-based synthetic resin waste is dissolved in a volume-reducing machine containing a solvent, the solution is transferred to an adjusting tank to adjust the concentration, and then a foreign matter in the solution is removed by centrifugation. , The separated liquid under reduced pressure of 40-60 Torr 210-2
A method for treating and recycling styrene-based synthetic resin waste, which comprises recovering a solvent by distillation separation treatment at a temperature of 60 ° C. and recovering dissolved polystyrene as a regenerated pellet. 2. The method for treating and recycling styrene-based synthetic resin waste according to claim 1, wherein a solution obtained by dissolving the styrene-based synthetic resin waste in a solvent is subjected to centrifugal separation at room temperature.